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Compilation error: can't find crate for std; the x86_64-linux-kernel target may not be installed #27

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wecing opened this issue Nov 19, 2020 · 6 comments · Fixed by #52
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• docs Related to `Documentation/rust/`, `samples/`, generated docs, doctests, typos...

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@wecing
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wecing commented Nov 19, 2020

Compiling the current head of the rust branch failed for me. Here is my setup:

> rustup toolchain install nightly-2020-08-27
> rustup default nightly-2020-08-27
> rustup component add rust-src
> cat .config | grep -E '(RUST|CARGO)'
CONFIG_HAS_RUST=y
CONFIG_RUSTC_VERSION=14700
CONFIG_CARGO_VERSION=14700
CONFIG_RUST_EXAMPLE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
# CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT is not set
CONFIG_SYSTEM_TRUSTED_KEYRING=y
CONFIG_SYSTEM_TRUSTED_KEYS=""
# CONFIG_SECONDARY_TRUSTED_KEYRING is not set
> make LLVM=1
  ...
  CARGO     arch/x86/entry/vdso/out/libvdso-image.a
   Compiling core v0.0.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core)
   Compiling kernel v0.1.0 (/home/$USER/Code/rust-for-linux/rust/kernel)
   Compiling rustc-std-workspace-core v1.99.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core)
   Compiling compiler_builtins v0.1.32
   Compiling alloc v0.0.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc)
   Compiling bitflags v1.2.1
   Compiling shlex v0.1.1 (/home/$USER/Code/rust-for-linux/rust/shlex)
error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-linux-kernel` target may not be installed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `shlex`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
make[3]: *** [scripts/Makefile.build:318: arch/x86/entry/vdso/out/libvdso-image.a] Error 101
make[2]: *** [scripts/Makefile.build:518: arch/x86/entry/vdso] Error 2
make[1]: *** [scripts/Makefile.build:518: arch/x86/entry] Error 2
make: *** [Makefile:1838: arch/x86] Error 2

Is there something missing in Documentation/rust/quick-start.rst?

@kloenk
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kloenk commented Nov 19, 2020

This should resolve itself, when #25 gets resolved.

@kloenk kloenk added the • docs Related to `Documentation/rust/`, `samples/`, generated docs, doctests, typos... label Nov 19, 2020
@wecing
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wecing commented Nov 19, 2020

@kloenk Is it possible to workaround this issue before #25 lands?

@ojeda ojeda added the required label Nov 28, 2020
@ojeda
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ojeda commented Nov 28, 2020

@wecing It may work now since we don't depend on shlex anymore and we use our own target. I also rewrote the quick start guide a bit, in case you want to take a look.

@wecing
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wecing commented Nov 29, 2020

@ojeda Thank you! Unfortunately it still doesn't work for me:

> git log -1
commit 514443c678e50021917dfe5b9e4a427559e9ec82 (HEAD -> rust, origin/rust, origin/HEAD)
Merge: 2874653450f 5c3df5ae897
Author: Miguel Ojeda
Date:   Sun Nov 29 00:03:27 2020 +0100

    Merge pull request #37 from Rust-for-Linux/rust-ci-builddir

    CI: test O= builds too
> make menuconfig
> make clean
> make LLVM=1
  ...
  CALL    scripts/checksyscalls.sh
  CALL    scripts/atomic/check-atomics.sh
  DESCEND  objtool
  CHK     include/generated/compile.h
  CARGO     arch/x86/entry/vdso/libvdso-image.a
error: manifest path `./arch/x86/entry/vdso/Cargo.toml` does not exist
make[3]: *** [scripts/Makefile.build:329: arch/x86/entry/vdso/libvdso-image.a] Error 101
make[2]: *** [scripts/Makefile.build:529: arch/x86/entry/vdso] Error 2
make[1]: *** [scripts/Makefile.build:529: arch/x86/entry] Error 2
make: *** [Makefile:1833: arch/x86] Error 2

Since the previous error message I saw was about rust std, I actually did try to compile that from latest rust source code:

> ./x.py build --stage 1 --host x86_64-unknown-linux-gnu --target x86_64-linux-kernel library/std
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-linux-kernel)
   Compiling libc v0.2.79
   ...
   Compiling object v0.22.0
   Compiling addr2line v0.14.0
   Compiling std v0.0.0 (/home/$USER/Code/sources/rust/library/std)
warning: dropping unsupported crate type `dylib` for target `x86_64-linux-kernel`

error[E0432]: unresolved imports `libc::c_int`, `libc::c_void`
  --> library/std/src/sys_common/net.rs:17:12
   |
17 | use libc::{c_int, c_void};
   |            ^^^^^  ^^^^^^ no `c_void` in the root
   |            |
   |            no `c_int` in the root

Not sure what was causing that failure, but it probably doesn't matter anymore.

@ojeda
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ojeda commented Nov 29, 2020

@wecing Thanks for trying again!

CARGO arch/x86/entry/vdso/libvdso-image.a

@kloenk This is triggered by the $(obj)/lib%.a change, now it matches things we don't want.

@kloenk
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kloenk commented Nov 29, 2020

@kloenk This is triggered by the $(obj)/lib%.a change, now it matches things we don't want.

Oh, not good. But without that change it also does not work. So no idea on how to fix it from my side at this time.

I changed it so, it detects if it's a module or a builtin.

ojeda added a commit that referenced this issue Dec 9, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure. Way less files around!

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Offline builds, always; i.e. there is no "online compilation"
    anymore (fixes #17).

  - No more interleaved Cargo output (fixes #29).

  - One less nightly dependency (Cargo's `build-std`); since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking `rustc` options, like overflow checks.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is one more nightly feature used (the new Rust mangling scheme),
    but we know that one will be stable (and the default one, later on).

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

There are a few TODOs that we can improve later if we agree on this:

  - Kbuild:

    + Actually use the `*.d` files.

    + Complete `make clean`.

    + Support single-object compilation.

    + Pass `objtool` to make the ORC unwinder work.

    + Echo the building of the rust/* libraries and the bindgen call.

  - Figure out how to pick symbols to export automatically from
    Rust code instead of managing the list by hand.

    Perhaps we could use a no-op macro on the Rust code, which is then
    parse by a script to pick up the symbols:

        pub fn foo() {}
        export_symbol!(foo);

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 9, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure. Way less files around!

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Offline builds, always; i.e. there is no "online compilation"
    anymore (fixes #17).

  - No more interleaved Cargo output (fixes #29).

  - One less nightly dependency (Cargo's `build-std`); since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking `rustc` options, like overflow checks.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is one more nightly feature used (the new Rust mangling scheme),
    but we know that one will be stable (and the default one, later on).

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

There are a few TODOs that we can improve later if we agree on this:

  - Kbuild:

    + Actually use the `*.d` files.

    + Complete `make clean`.

    + Support single-object compilation.

    + Pass `objtool` to make the ORC unwinder work.

    + Echo the building of the rust/* libraries and the bindgen call.

  - Figure out how to pick symbols to export automatically from
    Rust code instead of managing the list by hand.

    Perhaps we could use a no-op macro on the Rust code, which is then
    parse by a script to pick up the symbols:

        pub fn foo() {}
        export_symbol!(foo);

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 9, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure. Way less files around!

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Offline builds, always; i.e. there is no "online compilation"
    anymore (fixes #17).

  - No more interleaved Cargo output (fixes #29).

  - One less nightly dependency (Cargo's `build-std`); since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking `rustc` options, like overflow checks.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is one more nightly feature used (the new Rust mangling scheme),
    but we know that one will be stable (and the default one, later on).

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

There are a few TODOs that we can improve later if we agree on this:

  - Kbuild:

    + Actually use the `*.d` files.

    + Complete `make clean`.

    + Support single-object compilation.

    + Pass `objtool` to make the ORC unwinder work.

    + Echo the building of the rust/* libraries and the bindgen call.

  - Figure out how to pick symbols to export automatically from
    Rust code instead of managing the list by hand.

    Perhaps we could use a no-op macro on the Rust code, which is then
    parse by a script to pick up the symbols:

        pub fn foo() {}
        export_symbol!(foo);

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 9, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure. Way less files around!

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Offline builds, always; i.e. there is no "online compilation"
    anymore (fixes #17).

  - No more interleaved Cargo output (fixes #29).

  - One less nightly dependency (Cargo's `build-std`); since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking `rustc` options, like overflow checks.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is one more nightly feature used (the new Rust mangling scheme),
    but we know that one will be stable (and the default one, later on).

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

There are a few TODOs that we can improve later if we agree on this:

  - Kbuild:

    + Actually use the `*.d` files.

    + Complete `make clean`.

    + Support single-object compilation.

    + Pass `objtool` to make the ORC unwinder work.

    + Echo the building of the rust/* libraries and the bindgen call.

  - Figure out how to pick symbols to export automatically from
    Rust code instead of managing the list by hand.

    Perhaps we could use a no-op macro on the Rust code, which is then
    parse by a script to pick up the symbols:

        pub fn foo() {}
        export_symbol!(foo);

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 12, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, etc. all trigger
        recompilation of the proper things.

      + Works as expected with parallel support (`-j`).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No more interleaved Cargo output (fixes #29).

  - One less nightly dependency (Cargo's `build-std`); since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking `rustc` options, like overflow checks.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is one more nightly feature used (the new Rust mangling scheme),
    but we know that one will be stable (and the default one, later on).

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 16, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking relevant `rustc` options, like overflow
    checks, debug assertions, optimization level, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda pushed a commit that referenced this issue Dec 16, 2020
If cm_create_timewait_info() fails, the timewait_info pointer will contain
an error value and will be used in cm_remove_remote() later.

  general protection fault, probably for non-canonical address 0xdffffc0000000024: 0000 [#1] SMP KASAN PTI
  KASAN: null-ptr-deref in range [0×0000000000000120-0×0000000000000127]
  CPU: 2 PID: 12446 Comm: syz-executor.3 Not tainted 5.10.0-rc5-5d4c0742a60e #27
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
  RIP: 0010:cm_remove_remote.isra.0+0x24/0×170 drivers/infiniband/core/cm.c:978
  Code: 84 00 00 00 00 00 41 54 55 53 48 89 fb 48 8d ab 2d 01 00 00 e8 7d bf 4b fe 48 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 48 89 ea 83 e2 07 38 d0 7f 08 84 c0 0f 85 fc 00 00 00
  RSP: 0018:ffff888013127918 EFLAGS: 00010006
  RAX: dffffc0000000000 RBX: fffffffffffffff4 RCX: ffffc9000a18b000
  RDX: 0000000000000024 RSI: ffffffff82edc573 RDI: fffffffffffffff4
  RBP: 0000000000000121 R08: 0000000000000001 R09: ffffed1002624f1d
  R10: 0000000000000003 R11: ffffed1002624f1c R12: ffff888107760c70
  R13: ffff888107760c40 R14: fffffffffffffff4 R15: ffff888107760c9c
  FS:  00007fe1ffcc1700(0000) GS:ffff88811a600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000001b2ff21000 CR3: 000000010f504001 CR4: 0000000000370ee0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   cm_destroy_id+0x189/0×15b0 drivers/infiniband/core/cm.c:1155
   cma_connect_ib drivers/infiniband/core/cma.c:4029 [inline]
   rdma_connect_locked+0x1100/0×17c0 drivers/infiniband/core/cma.c:4107
   rdma_connect+0x2a/0×40 drivers/infiniband/core/cma.c:4140
   ucma_connect+0x277/0×340 drivers/infiniband/core/ucma.c:1069
   ucma_write+0x236/0×2f0 drivers/infiniband/core/ucma.c:1724
   vfs_write+0x220/0×830 fs/read_write.c:603
   ksys_write+0x1df/0×240 fs/read_write.c:658
   do_syscall_64+0x33/0×40 arch/x86/entry/common.c:46
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: a977049 ("[PATCH] IB: Add the kernel CM implementation")
Link: https://lore.kernel.org/r/20201204064205.145795-1-leon@kernel.org
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Reported-by: Amit Matityahu <mitm@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
ojeda added a commit that referenced this issue Dec 16, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    following what the user selected for C (no Cargo profiles).

  - Added Kconfig menu for tweaking relevant `rustc` options, like overflow
    checks, debug assertions, optimization level, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.9 while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 20, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels.

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks, debug assertions, etc.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Updated the quick start guide.

  - Updated CI `.config`s:

      + Add the new options and test with 2 builtins and 2 loadables.
        At the same time, remove the matrix test for builtin/loadable.

      + Updated with `toolchain` matrix support: now we test building
        with GCC, Clang or a full LLVM toolchain.

      + Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
        that mimic more what a developer would have. Running the CI
        will be slightly slower, but should be OK. Also enable
        `-C opt-level=0` to test that such an extreme works and also
        to see how much bloated everything becomes.

      + Release: disabled `EXPERT` and changed a few things to make it
        look more like a normal configuration.

      + Also update both configs to v5.10 and `LLVM=1` while I was at it.

    (I could have split a few of these ones off into another PR,
    but anyway it is for the CI only and I had already done it).

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Dec 28, 2020
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 2, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 3, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 10, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 10, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
@alex alex added this to the initial-upstream-required milestone Jan 12, 2021
@alex alex removed this from the initial-upstream-required milestone Jan 13, 2021
ojeda added a commit that referenced this issue Jan 16, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 19, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
ojeda added a commit that referenced this issue Jan 19, 2021
This is a big PR, but most of it is interdependent to the rest.

  - Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
    `liballoc`, `libcompiler_builtins`.

      + The Rust modules are now much smaller since they do not contain
        several copies of those libraries. Our example `.ko` on release
        is just 12 KiB, down from 1.3 MiB. For reference:

            `vmlinux` on release w/  Rust is 23 MiB (compressed: 2.1 MiB)
            `vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)

        i.e. the bulk is now shared.

      + Multiple builtin modules are now supported since their symbols
        do not collide against each other (fixes #9).

      + Faster compilation (less crates to compile & less repetition).

      + We achieve this by compiling all the shared code to `.rlib`s
        (and the `.so` for the proc macro). For loadable modules,
        we need to rely on the upcoming v0 Rust mangling scheme,
        plus we need to export the Rust symbols needed by the `.ko`s.

  - Simpler, flat file structure: now a small driver may only need
    a single file like `drivers/char/rust_example.rs`, like in C.

      + All the `rust/*` and `driver/char/rust_example/*` files moved
        to fit in the new structure: less files around.

  - Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.

      + Also helps with the faster compilation.

  - Dependency handling integration with `Kbuild`/`fixdep`.

      + Changes to the Rust standard library, kernel headers (bindings),
        `rust/` source files, `.rs` changes, command-line changes,
        flag changes, etc. all trigger recompilation as needed.

      + Works as expected with parallel support (`-j`).

  - Automatic generation of the `exports.c` list:

      + Instead of manually handling the list, all non-local functions
        available in `core`, `alloc` and `kernel` are exported, so all
        modules should work, regardless of what they need, and without
        failing linking due to symbols in the manual list not existing
        (e.g. due to differences in config options).

      + They are a lot, though:

          * ~6k Rust symbols vs. ~4k C symbols in release.

          * However, 4k of those are `bindings_raw` (i.e. duplicated C
            ones), which shouldn't be exported. Thus we should look
            into making `bindings_raw` private to the crate (at the
            moment, the (first) Rust example requires
            `<kernel::bindings...::miscdevice as Default>::default`).

      + Licensing:

          * `kernel`'s symbols are exported as GPL.

          * `core`'s and `alloc`'s symbols are exported as non-GPL so
            that third-parties can build Rust modules as long as they
            write their own kernel support infrastructure, i.e. without
            taking advantage of `kernel`. This seemed to make the most
            sense compared to other exports from the kernel, plus it
            follows more closely the original licence of the crates.

  - Support for GCC-compiled kernels:

    + The generated bindings do not have meaningful differences in our
      release config, between GCC 10.1 and Clang 11.

    + Other configs (e.g. our debug one) may add/remove types and functions.
      That is fine unless we use them form our bindings.

    + However, there are config options that may not work (e.g.
      the randstruct GCC plugin if we use one of those structs).

  - Support for `arm64` architecture:

    + Added to the CI: BusyBox is cross-compiled on the fly (increased
      timeout a bit to match).

    + Requires weakening of a few compiler builtins and adding
      `copy_{from,to}_user` helpers.

  - Support for custom `--sysroot` via `KRUSTCFLAGS`.

  - Proper `make clean` support.

  - Offline builds by default (there is no "online compilation" anymore;
    fixes #17).

  - No interleaved Cargo output (fixes #29).

  - No nightly dependency on Cargo's `build-std`; since now we manage
    the cross-compilation ourselves (should fix #27).

  - "Big" kallsyms symbol support:

    + I already raised ksym names from 128 to 256 back when I wrote the first
      integration. However, Rust symbols can be huge in debug/non-optimized,
      so I increased it again to 512; plus the module name from 56 to 248.

    + In turn, this required tuning the table format to support 2-byte lengths
      for ksyms. Compression at generation and kernel decompression is covered,
      although it may be the case that some script/tool also requires changes
      to understand the new table format.

  - Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
    is added to enable/disable it manually, regardless of whether one has
    `rustc` available or not (`CONFIG_HAS_RUST`).

  - Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
    by default following what the user selected for C, but customizable
    through a Kconfig menu. As well as options for tweaking overflow
    checks and debug assertions.

  - This rewrite of the Kbuild support is cleaner, i.e. less hacks
    in general handling paths (e.g. no more `shell readlink` for `O=`).

  - Duplicated the example driver 3 times so that we can test in the CI
    that 2 builtins and 2 loadables work, all at the same time.

  - Do not export any helpers' symbols.

  - Updated the quick start guide.

  - Updated CI:

      + Now we always test with 2 builtins and 2 loadables Rust example
        drivers, removing the matrix test for builtin/loadable.

      + Added `toolchain` to matrix: now we test building with GCC,
        Clang or a full LLVM toolchain.

      + Added `arch` to matrix: now we test both arm64 and x86_64.

      + Added `rustc` to matrix: now we test with a very recent nightly
        as well.

      + Only build `output == build` once to reduce the number
        of combinations.

      + Debug x86_64 config: more things enabled (debuginfo, kgdb,
        unit testing, etc.) that mimic more what a developer would have.
        Running the CI will be slightly slower, but should be OK.
        Also enable `-C opt-level=0` to test that such an extreme works
        and also to see how much bloated everything becomes.

      + Release x86_64 config: disabled `EXPERT` and changed a few things
        to make it look more like a normal desktop configuration,
        although it is still pretty minimal.

      + The configs for arm64 are `EXPERT` and `EMBEDDED` ones,
        very minimal, for the particular CPU we are simulating.

      + Update configs to v5.10.

      + Use `$GITHUB_ENV` to simplify.

  - Less `extern crate`s needed since we pass it via `rustc`
    (closer to idiomatic 2018 edition Rust code).

Things to note:

  - There is two more nightly features used:

      + The new Rust mangling scheme: we know it will be stable
        (and the default on, later on).

      + The binary dep-info output: if we remove all other nightly
        features, this one can easily go too.

  - The hack at `exports.c` to export symbols to loadable modules.

  - The hack at `allocator.rs` to get the `__rust_*()` functions.

  - The hack to get the proper flags for bindgen on GCC builds.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
@ojeda ojeda closed this as completed in #52 Jan 21, 2021
AltF02 pushed a commit to AltF02/linux that referenced this issue Oct 5, 2021
Minimal selftest which implements a small BPF policy program to the
connect(2) hook which rejects TCP connection requests to port 60123
with EPERM. This is being attached to a non-root cgroup v2 path. The
test asserts that this works under cgroup v2-only and under a mixed
cgroup v1/v2 environment where net_classid is set in the former case.

Before fix:

  # ./test_progs -t cgroup_v1v2
  test_cgroup_v1v2:PASS:server_fd 0 nsec
  test_cgroup_v1v2:PASS:client_fd 0 nsec
  test_cgroup_v1v2:PASS:cgroup_fd 0 nsec
  test_cgroup_v1v2:PASS:server_fd 0 nsec
  run_test:PASS:skel_open 0 nsec
  run_test:PASS:prog_attach 0 nsec
  test_cgroup_v1v2:PASS:cgroup-v2-only 0 nsec
  run_test:PASS:skel_open 0 nsec
  run_test:PASS:prog_attach 0 nsec
  run_test:PASS:join_classid 0 nsec
  (network_helpers.c:219: errno: None) Unexpected success to connect to server
  test_cgroup_v1v2:FAIL:cgroup-v1v2 unexpected error: -1 (errno 0)
  Rust-for-Linux#27 cgroup_v1v2:FAIL
  Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED

After fix:

  # ./test_progs -t cgroup_v1v2
  Rust-for-Linux#27 cgroup_v1v2:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210913230759.2313-3-daniel@iogearbox.net
ojeda pushed a commit that referenced this issue Mar 14, 2022
high_memory used to be initialized in mem_init, way after setup_bootmem.
But a call to dma_contiguous_reserve in this function gives rise to the
below warning because high_memory is equal to 0 and is used at the very
beginning at cma_declare_contiguous_nid.

It went unnoticed since the move of the kasan region redefined
KERN_VIRT_SIZE so that it does not encompass -1 anymore.

Fix this by initializing high_memory in setup_bootmem.

------------[ cut here ]------------
virt_to_phys used for non-linear address: ffffffffffffffff (0xffffffffffffffff)
WARNING: CPU: 0 PID: 0 at arch/riscv/mm/physaddr.c:14 __virt_to_phys+0xac/0x1b8
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.17.0-rc1-00007-ga68b89289e26 #27
Hardware name: riscv-virtio,qemu (DT)
epc : __virt_to_phys+0xac/0x1b8
 ra : __virt_to_phys+0xac/0x1b8
epc : ffffffff80014922 ra : ffffffff80014922 sp : ffffffff84a03c30
 gp : ffffffff85866c80 tp : ffffffff84a3f180 t0 : ffffffff86bce657
 t1 : fffffffef09406e8 t2 : 0000000000000000 s0 : ffffffff84a03c70
 s1 : ffffffffffffffff a0 : 000000000000004f a1 : 00000000000f0000
 a2 : 0000000000000002 a3 : ffffffff8011f408 a4 : 0000000000000000
 a5 : 0000000000000000 a6 : 0000000000f00000 a7 : ffffffff84a03747
 s2 : ffffffd800000000 s3 : ffffffff86ef4000 s4 : ffffffff8467f828
 s5 : fffffff800000000 s6 : 8000000000006800 s7 : 0000000000000000
 s8 : 0000000480000000 s9 : 0000000080038ea0 s10: 0000000000000000
 s11: ffffffffffffffff t3 : ffffffff84a035c0 t4 : fffffffef09406e8
 t5 : fffffffef09406e9 t6 : ffffffff84a03758
status: 0000000000000100 badaddr: 0000000000000000 cause: 0000000000000003
[<ffffffff8322ef4c>] cma_declare_contiguous_nid+0xf2/0x64a
[<ffffffff83212a58>] dma_contiguous_reserve_area+0x46/0xb4
[<ffffffff83212c3a>] dma_contiguous_reserve+0x174/0x18e
[<ffffffff83208fc2>] paging_init+0x12c/0x35e
[<ffffffff83206bd2>] setup_arch+0x120/0x74e
[<ffffffff83201416>] start_kernel+0xce/0x68c
irq event stamp: 0
hardirqs last  enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<0000000000000000>] 0x0
softirqs last  enabled at (0): [<0000000000000000>] 0x0
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace 0000000000000000 ]---

Fixes: f7ae023 ("riscv: Move KASAN mapping next to the kernel mapping")
Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
ojeda pushed a commit that referenced this issue Apr 12, 2022
when get fiemap starting from MAX_LFS_FILESIZE, (maxbytes - *len) < start
will always true , then *len set zero. because of start offset is beyond
file size, for erofs filesystem it will always return iomap.length with
zero,iomap iterate will enter infinite loop. it is necessary cover this
corner case to avoid this situation.

------------[ cut here ]------------
WARNING: CPU: 7 PID: 905 at fs/iomap/iter.c:35 iomap_iter+0x97f/0xc70
Modules linked in: xfs erofs
CPU: 7 PID: 905 Comm: iomap Tainted: G        W         5.17.0-rc8 #27
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:iomap_iter+0x97f/0xc70
Code: 85 a1 fc ff ff e8 71 be 9c ff 0f 1f 44 00 00 e9 92 fc ff ff e8 62 be 9c ff 0f 0b b8 fb ff ff ff e9 fc f8 ff ff e8 51 be 9c ff <0f> 0b e9 2b fc ff ff e8 45 be 9c ff 0f 0b e9 e1 fb ff ff e8 39 be
RSP: 0018:ffff888060a37ab0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888060a37bb0 RCX: 0000000000000000
RDX: ffff88807e19a900 RSI: ffffffff81a7da7f RDI: ffff888060a37be0
RBP: 7fffffffffffffff R08: 0000000000000000 R09: ffff888060a37c20
R10: ffff888060a37c67 R11: ffffed100c146f8c R12: 7fffffffffffffff
R13: 0000000000000000 R14: ffff888060a37bd8 R15: ffff888060a37c20
FS:  00007fd3cca01540(0000) GS:ffff888108780000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020010820 CR3: 0000000054b92000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 iomap_fiemap+0x1c9/0x2f0
 erofs_fiemap+0x64/0x90 [erofs]
 do_vfs_ioctl+0x40d/0x12e0
 __x64_sys_ioctl+0xaa/0x1c0
 do_syscall_64+0x35/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
 </TASK>
---[ end trace 0000000000000000 ]---
watchdog: BUG: soft lockup - CPU#7 stuck for 26s! [iomap:905]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[djwong: fix some typos]
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
ojeda pushed a commit that referenced this issue May 4, 2022
+new file mode 100644
+WARNING: Missing or malformed SPDX-License-Identifier tag in line 1
+#27: FILE: Documentation/virt/kvm/x86/errata.rst:1:

Opportunistically update all other non-added KVM documents and
remove a new extra blank line at EOF for x86/errata.rst.

Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220406063715.55625-5-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
ojeda pushed a commit that referenced this issue May 4, 2022
Given a sufficiently large number of actions, while copying and
reserving memory for a new action of a new flow, if next_offset is
greater than MAX_ACTIONS_BUFSIZE, the function reserve_sfa_size() does
not return -EMSGSIZE as expected, but it allocates MAX_ACTIONS_BUFSIZE
bytes increasing actions_len by req_size. This can then lead to an OOB
write access, especially when further actions need to be copied.

Fix it by rearranging the flow action size check.

KASAN splat below:

==================================================================
BUG: KASAN: slab-out-of-bounds in reserve_sfa_size+0x1ba/0x380 [openvswitch]
Write of size 65360 at addr ffff888147e4001c by task handler15/836

CPU: 1 PID: 836 Comm: handler15 Not tainted 5.18.0-rc1+ #27
...
Call Trace:
 <TASK>
 dump_stack_lvl+0x45/0x5a
 print_report.cold+0x5e/0x5db
 ? __lock_text_start+0x8/0x8
 ? reserve_sfa_size+0x1ba/0x380 [openvswitch]
 kasan_report+0xb5/0x130
 ? reserve_sfa_size+0x1ba/0x380 [openvswitch]
 kasan_check_range+0xf5/0x1d0
 memcpy+0x39/0x60
 reserve_sfa_size+0x1ba/0x380 [openvswitch]
 __add_action+0x24/0x120 [openvswitch]
 ovs_nla_add_action+0xe/0x20 [openvswitch]
 ovs_ct_copy_action+0x29d/0x1130 [openvswitch]
 ? __kernel_text_address+0xe/0x30
 ? unwind_get_return_address+0x56/0xa0
 ? create_prof_cpu_mask+0x20/0x20
 ? ovs_ct_verify+0xf0/0xf0 [openvswitch]
 ? prep_compound_page+0x198/0x2a0
 ? __kasan_check_byte+0x10/0x40
 ? kasan_unpoison+0x40/0x70
 ? ksize+0x44/0x60
 ? reserve_sfa_size+0x75/0x380 [openvswitch]
 __ovs_nla_copy_actions+0xc26/0x2070 [openvswitch]
 ? __zone_watermark_ok+0x420/0x420
 ? validate_set.constprop.0+0xc90/0xc90 [openvswitch]
 ? __alloc_pages+0x1a9/0x3e0
 ? __alloc_pages_slowpath.constprop.0+0x1da0/0x1da0
 ? unwind_next_frame+0x991/0x1e40
 ? __mod_node_page_state+0x99/0x120
 ? __mod_lruvec_page_state+0x2e3/0x470
 ? __kasan_kmalloc_large+0x90/0xe0
 ovs_nla_copy_actions+0x1b4/0x2c0 [openvswitch]
 ovs_flow_cmd_new+0x3cd/0xb10 [openvswitch]
 ...

Cc: stable@vger.kernel.org
Fixes: f28cd2a ("openvswitch: fix flow actions reallocation")
Signed-off-by: Paolo Valerio <pvalerio@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
y86-dev pushed a commit to y86-dev/linux that referenced this issue Oct 3, 2022
Broadcom 4377 controllers found in Apple x86 Macs with the T2 chip
claim to support extended scanning when querying supported states,

< HCI Command: LE Read Supported St.. (0x08|0x001c) plen 0  Rust-for-Linux#27 [hci0] 2.971839
> HCI Event: Command Complete (0x0e) plen 12                Rust-for-Linux#28 [hci0] 2.972730
      LE Read Supported States (0x08|0x001c) ncmd 1
        Status: Success (0x00)
        States: 0x000003ffffffffff
[...]
          LE Set Extended Scan Parameters (Octet 37 - Bit 5)
          LE Set Extended Scan Enable (Octet 37 - Bit 6)
[...]

, but then fail to actually implement the extended scanning:

< HCI Command: LE Set Extended Sca.. (0x08|0x0041) plen 8  Rust-for-Linux#105 [hci0] 5.460776
        Own address type: Random (0x01)
        Filter policy: Accept all advertisement (0x00)
        PHYs: 0x01
        Entry 0: LE 1M
          Type: Active (0x01)
          Interval: 11.250 msec (0x0012)
          Window: 11.250 msec (0x0012)
> HCI Event: Command Complete (0x0e) plen 4                Rust-for-Linux#106 [hci0] 5.461777
      LE Set Extended Scan Parameters (0x08|0x0041) ncmd 1
        Status: Unknown HCI Command (0x01)

Signed-off-by: Sven Peter <sven@svenpeter.dev>
psomas pushed a commit to psomas/linux-rs that referenced this issue Dec 30, 2022
We use uprobe in aarch64_be, which we found the tracee task would exit
due to SIGILL when we enable the uprobe trace.
We can see the replace inst from uprobe is not correct in aarch big-endian.
As in Armv8-A, instruction fetches are always treated as little-endian,
we should treat the UPROBE_SWBP_INSN as little-endian。

The test case is as following。
bash-4.4# ./mqueue_test_aarchbe 1 1 2 1 10 > /dev/null &
bash-4.4# cd /sys/kernel/debug/tracing/
bash-4.4# echo 'p:test /mqueue_test_aarchbe:0xc30 %x0 %x1' > uprobe_events
bash-4.4# echo 1 > events/uprobes/enable
bash-4.4#
bash-4.4# ps
  PID TTY          TIME CMD
  140 ?        00:00:01 bash
  237 ?        00:00:00 ps
[1]+  Illegal instruction     ./mqueue_test_aarchbe 1 1 2 1 100 > /dev/null

which we debug use gdb as following:

bash-4.4# gdb attach 155
(gdb) disassemble send
Dump of assembler code for function send:
   0x0000000000400c30 <+0>:     .inst   0xa00020d4 ; undefined
   0x0000000000400c34 <+4>:     mov     x29, sp
   0x0000000000400c38 <+8>:     str     w0, [sp, Rust-for-Linux#28]
   0x0000000000400c3c <+12>:    strb    w1, [sp, Rust-for-Linux#27]
   0x0000000000400c40 <+16>:    str     xzr, [sp, Rust-for-Linux#40]
   0x0000000000400c44 <+20>:    str     xzr, [sp, Rust-for-Linux#48]
   0x0000000000400c48 <+24>:    add     x0, sp, #0x1b
   0x0000000000400c4c <+28>:    mov     w3, #0x0                 // #0
   0x0000000000400c50 <+32>:    mov     x2, #0x1                 // Rust-for-Linux#1
   0x0000000000400c54 <+36>:    mov     x1, x0
   0x0000000000400c58 <+40>:    ldr     w0, [sp, Rust-for-Linux#28]
   0x0000000000400c5c <+44>:    bl      0x405e10 <mq_send>
   0x0000000000400c60 <+48>:    str     w0, [sp, Rust-for-Linux#60]
   0x0000000000400c64 <+52>:    ldr     w0, [sp, Rust-for-Linux#60]
   0x0000000000400c68 <+56>:    ldp     x29, x30, [sp], Rust-for-Linux#64
   0x0000000000400c6c <+60>:    ret
End of assembler dump.
(gdb) info b
No breakpoints or watchpoints.
(gdb) c
Continuing.

Program received signal SIGILL, Illegal instruction.
0x0000000000400c30 in send ()
(gdb) x/10x 0x400c30
0x400c30 <send>:    0xd42000a0   0xfd030091      0xe01f00b9      0xe16f0039
0x400c40 <send+16>: 0xff1700f9   0xff1b00f9      0xe06f0091      0x03008052
0x400c50 <send+32>: 0x220080d2   0xe10300aa
(gdb) disassemble 0x400c30
Dump of assembler code for function send:
=> 0x0000000000400c30 <+0>:     .inst   0xa00020d4 ; undefined
   0x0000000000400c34 <+4>:     mov     x29, sp
   0x0000000000400c38 <+8>:     str     w0, [sp, Rust-for-Linux#28]
   0x0000000000400c3c <+12>:    strb    w1, [sp, Rust-for-Linux#27]
   0x0000000000400c40 <+16>:    str     xzr, [sp, Rust-for-Linux#40]

Signed-off-by: junhua huang <huang.junhua@zte.com.cn>
Link: https://lore.kernel.org/r/202212021511106844809@zte.com.cn
Signed-off-by: Will Deacon <will@kernel.org>
fbq pushed a commit that referenced this issue Sep 25, 2023
The following processes run into a deadlock. CPU 41 was waiting for CPU 29
to handle a CSD request while holding spinlock "crashdump_lock", but CPU 29
was hung by that spinlock with IRQs disabled.

  PID: 17360    TASK: ffff95c1090c5c40  CPU: 41  COMMAND: "mrdiagd"
  !# 0 [ffffb80edbf37b58] __read_once_size at ffffffff9b871a40 include/linux/compiler.h:185:0
  !# 1 [ffffb80edbf37b58] atomic_read at ffffffff9b871a40 arch/x86/include/asm/atomic.h:27:0
  !# 2 [ffffb80edbf37b58] dump_stack at ffffffff9b871a40 lib/dump_stack.c:54:0
   # 3 [ffffb80edbf37b78] csd_lock_wait_toolong at ffffffff9b131ad5 kernel/smp.c:364:0
   # 4 [ffffb80edbf37b78] __csd_lock_wait at ffffffff9b131ad5 kernel/smp.c:384:0
   # 5 [ffffb80edbf37bf8] csd_lock_wait at ffffffff9b13267a kernel/smp.c:394:0
   # 6 [ffffb80edbf37bf8] smp_call_function_many at ffffffff9b13267a kernel/smp.c:843:0
   # 7 [ffffb80edbf37c50] smp_call_function at ffffffff9b13279d kernel/smp.c:867:0
   # 8 [ffffb80edbf37c50] on_each_cpu at ffffffff9b13279d kernel/smp.c:976:0
   # 9 [ffffb80edbf37c78] flush_tlb_kernel_range at ffffffff9b085c4b arch/x86/mm/tlb.c:742:0
   #10 [ffffb80edbf37cb8] __purge_vmap_area_lazy at ffffffff9b23a1e0 mm/vmalloc.c:701:0
   #11 [ffffb80edbf37ce0] try_purge_vmap_area_lazy at ffffffff9b23a2cc mm/vmalloc.c:722:0
   #12 [ffffb80edbf37ce0] free_vmap_area_noflush at ffffffff9b23a2cc mm/vmalloc.c:754:0
   #13 [ffffb80edbf37cf8] free_unmap_vmap_area at ffffffff9b23bb3b mm/vmalloc.c:764:0
   #14 [ffffb80edbf37cf8] remove_vm_area at ffffffff9b23bb3b mm/vmalloc.c:1509:0
   #15 [ffffb80edbf37d18] __vunmap at ffffffff9b23bb8a mm/vmalloc.c:1537:0
   #16 [ffffb80edbf37d40] vfree at ffffffff9b23bc85 mm/vmalloc.c:1612:0
   #17 [ffffb80edbf37d58] megasas_free_host_crash_buffer [megaraid_sas] at ffffffffc020b7f2 drivers/scsi/megaraid/megaraid_sas_fusion.c:3932:0
   #18 [ffffb80edbf37d80] fw_crash_state_store [megaraid_sas] at ffffffffc01f804d drivers/scsi/megaraid/megaraid_sas_base.c:3291:0
   #19 [ffffb80edbf37dc0] dev_attr_store at ffffffff9b56dd7b drivers/base/core.c:758:0
   #20 [ffffb80edbf37dd0] sysfs_kf_write at ffffffff9b326acf fs/sysfs/file.c:144:0
   #21 [ffffb80edbf37de0] kernfs_fop_write at ffffffff9b325fd4 fs/kernfs/file.c:316:0
   #22 [ffffb80edbf37e20] __vfs_write at ffffffff9b29418a fs/read_write.c:480:0
   #23 [ffffb80edbf37ea8] vfs_write at ffffffff9b294462 fs/read_write.c:544:0
   #24 [ffffb80edbf37ee8] SYSC_write at ffffffff9b2946ec fs/read_write.c:590:0
   #25 [ffffb80edbf37ee8] SyS_write at ffffffff9b2946ec fs/read_write.c:582:0
   #26 [ffffb80edbf37f30] do_syscall_64 at ffffffff9b003ca9 arch/x86/entry/common.c:298:0
   #27 [ffffb80edbf37f58] entry_SYSCALL_64 at ffffffff9ba001b1 arch/x86/entry/entry_64.S:238:0

  PID: 17355    TASK: ffff95c1090c3d80  CPU: 29  COMMAND: "mrdiagd"
  !# 0 [ffffb80f2d3c7d30] __read_once_size at ffffffff9b0f2ab0 include/linux/compiler.h:185:0
  !# 1 [ffffb80f2d3c7d30] native_queued_spin_lock_slowpath at ffffffff9b0f2ab0 kernel/locking/qspinlock.c:368:0
   # 2 [ffffb80f2d3c7d58] pv_queued_spin_lock_slowpath at ffffffff9b0f244b arch/x86/include/asm/paravirt.h:674:0
   # 3 [ffffb80f2d3c7d58] queued_spin_lock_slowpath at ffffffff9b0f244b arch/x86/include/asm/qspinlock.h:53:0
   # 4 [ffffb80f2d3c7d68] queued_spin_lock at ffffffff9b8961a6 include/asm-generic/qspinlock.h:90:0
   # 5 [ffffb80f2d3c7d68] do_raw_spin_lock_flags at ffffffff9b8961a6 include/linux/spinlock.h:173:0
   # 6 [ffffb80f2d3c7d68] __raw_spin_lock_irqsave at ffffffff9b8961a6 include/linux/spinlock_api_smp.h:122:0
   # 7 [ffffb80f2d3c7d68] _raw_spin_lock_irqsave at ffffffff9b8961a6 kernel/locking/spinlock.c:160:0
   # 8 [ffffb80f2d3c7d88] fw_crash_buffer_store [megaraid_sas] at ffffffffc01f8129 drivers/scsi/megaraid/megaraid_sas_base.c:3205:0
   # 9 [ffffb80f2d3c7dc0] dev_attr_store at ffffffff9b56dd7b drivers/base/core.c:758:0
   #10 [ffffb80f2d3c7dd0] sysfs_kf_write at ffffffff9b326acf fs/sysfs/file.c:144:0
   #11 [ffffb80f2d3c7de0] kernfs_fop_write at ffffffff9b325fd4 fs/kernfs/file.c:316:0
   #12 [ffffb80f2d3c7e20] __vfs_write at ffffffff9b29418a fs/read_write.c:480:0
   #13 [ffffb80f2d3c7ea8] vfs_write at ffffffff9b294462 fs/read_write.c:544:0
   #14 [ffffb80f2d3c7ee8] SYSC_write at ffffffff9b2946ec fs/read_write.c:590:0
   #15 [ffffb80f2d3c7ee8] SyS_write at ffffffff9b2946ec fs/read_write.c:582:0
   #16 [ffffb80f2d3c7f30] do_syscall_64 at ffffffff9b003ca9 arch/x86/entry/common.c:298:0
   #17 [ffffb80f2d3c7f58] entry_SYSCALL_64 at ffffffff9ba001b1 arch/x86/entry/entry_64.S:238:0

The lock is used to synchronize different sysfs operations, it doesn't
protect any resource that will be touched by an interrupt. Consequently
it's not required to disable IRQs. Replace the spinlock with a mutex to fix
the deadlock.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Link: https://lore.kernel.org/r/20230828221018.19471-1-junxiao.bi@oracle.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
metaspace pushed a commit to metaspace/linux that referenced this issue Mar 12, 2024
It appears the client object tree has no locking unless I've missed
something else. Fix races around adding/removing client objects,
mostly vram bar mappings.

 4562.099306] general protection fault, probably for non-canonical address 0x6677ed422bceb80c: 0000 [#1] PREEMPT SMP PTI
[ 4562.099314] CPU: 2 PID: 23171 Comm: deqp-vk Not tainted 6.8.0-rc6+ Rust-for-Linux#27
[ 4562.099324] Hardware name: Gigabyte Technology Co., Ltd. Z390 I AORUS PRO WIFI/Z390 I AORUS PRO WIFI-CF, BIOS F8 11/05/2021
[ 4562.099330] RIP: 0010:nvkm_object_search+0x1d/0x70 [nouveau]
[ 4562.099503] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 0f 1f 44 00 00 48 89 f8 48 85 f6 74 39 48 8b 87 a0 00 00 00 48 85 c0 74 12 <48> 8b 48 f8 48 39 ce 73 15 48 8b 40 10 48 85 c0 75 ee 48 c7 c0 fe
[ 4562.099506] RSP: 0000:ffffa94cc420bbf8 EFLAGS: 00010206
[ 4562.099512] RAX: 6677ed422bceb814 RBX: ffff98108791f400 RCX: ffff9810f26b8f58
[ 4562.099517] RDX: 0000000000000000 RSI: ffff9810f26b9158 RDI: ffff98108791f400
[ 4562.099519] RBP: ffff9810f26b9158 R08: 0000000000000000 R09: 0000000000000000
[ 4562.099521] R10: ffffa94cc420bc48 R11: 0000000000000001 R12: ffff9810f02a7cc0
[ 4562.099526] R13: 0000000000000000 R14: 00000000000000ff R15: 0000000000000007
[ 4562.099528] FS:  00007f629c5017c0(0000) GS:ffff98142c700000(0000) knlGS:0000000000000000
[ 4562.099534] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4562.099536] CR2: 00007f629a882000 CR3: 000000017019e004 CR4: 00000000003706f0
[ 4562.099541] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 4562.099542] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 4562.099544] Call Trace:
[ 4562.099555]  <TASK>
[ 4562.099573]  ? die_addr+0x36/0x90
[ 4562.099583]  ? exc_general_protection+0x246/0x4a0
[ 4562.099593]  ? asm_exc_general_protection+0x26/0x30
[ 4562.099600]  ? nvkm_object_search+0x1d/0x70 [nouveau]
[ 4562.099730]  nvkm_ioctl+0xa1/0x250 [nouveau]
[ 4562.099861]  nvif_object_map_handle+0xc8/0x180 [nouveau]
[ 4562.099986]  nouveau_ttm_io_mem_reserve+0x122/0x270 [nouveau]
[ 4562.100156]  ? dma_resv_test_signaled+0x26/0xb0
[ 4562.100163]  ttm_bo_vm_fault_reserved+0x97/0x3c0 [ttm]
[ 4562.100182]  ? __mutex_unlock_slowpath+0x2a/0x270
[ 4562.100189]  nouveau_ttm_fault+0x69/0xb0 [nouveau]
[ 4562.100356]  __do_fault+0x32/0x150
[ 4562.100362]  do_fault+0x7c/0x560
[ 4562.100369]  __handle_mm_fault+0x800/0xc10
[ 4562.100382]  handle_mm_fault+0x17c/0x3e0
[ 4562.100388]  do_user_addr_fault+0x208/0x860
[ 4562.100395]  exc_page_fault+0x7f/0x200
[ 4562.100402]  asm_exc_page_fault+0x26/0x30
[ 4562.100412] RIP: 0033:0x9b9870
[ 4562.100419] Code: 85 a8 f7 ff ff 8b 8d 80 f7 ff ff 89 08 e9 18 f2 ff ff 0f 1f 84 00 00 00 00 00 44 89 32 e9 90 fa ff ff 0f 1f 84 00 00 00 00 00 <44> 89 32 e9 f8 f1 ff ff 0f 1f 84 00 00 00 00 00 66 44 89 32 e9 e7
[ 4562.100422] RSP: 002b:00007fff9ba2dc70 EFLAGS: 00010246
[ 4562.100426] RAX: 0000000000000004 RBX: 000000000dd65e10 RCX: 000000fff0000000
[ 4562.100428] RDX: 00007f629a882000 RSI: 00007f629a882000 RDI: 0000000000000066
[ 4562.100432] RBP: 00007fff9ba2e570 R08: 0000000000000000 R09: 0000000123ddf000
[ 4562.100434] R10: 0000000000000001 R11: 0000000000000246 R12: 000000007fffffff
[ 4562.100436] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 4562.100446]  </TASK>
[ 4562.100448] Modules linked in: nf_conntrack_netbios_ns nf_conntrack_broadcast nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables libcrc32c nfnetlink cmac bnep sunrpc iwlmvm intel_rapl_msr intel_rapl_common snd_sof_pci_intel_cnl x86_pkg_temp_thermal intel_powerclamp snd_sof_intel_hda_common mac80211 coretemp snd_soc_acpi_intel_match kvm_intel snd_soc_acpi snd_soc_hdac_hda snd_sof_pci snd_sof_xtensa_dsp snd_sof_intel_hda_mlink snd_sof_intel_hda snd_sof kvm snd_sof_utils snd_soc_core snd_hda_codec_realtek libarc4 snd_hda_codec_generic snd_compress snd_hda_ext_core vfat fat snd_hda_intel snd_intel_dspcfg irqbypass iwlwifi snd_hda_codec snd_hwdep snd_hda_core btusb btrtl mei_hdcp iTCO_wdt rapl mei_pxp btintel snd_seq iTCO_vendor_support btbcm snd_seq_device intel_cstate bluetooth snd_pcm cfg80211 intel_wmi_thunderbolt wmi_bmof intel_uncore snd_timer mei_me snd ecdh_generic i2c_i801
[ 4562.100541]  ecc mei i2c_smbus soundcore rfkill intel_pch_thermal acpi_pad zram nouveau drm_ttm_helper ttm gpu_sched i2c_algo_bit drm_gpuvm drm_exec mxm_wmi drm_display_helper drm_kms_helper drm crct10dif_pclmul crc32_pclmul nvme e1000e crc32c_intel nvme_core ghash_clmulni_intel video wmi pinctrl_cannonlake ip6_tables ip_tables fuse
[ 4562.100616] ---[ end trace 0000000000000000 ]---

Signed-off-by: Dave Airlie <airlied@redhat.com>
Cc: stable@vger.kernel.org
ojeda pushed a commit that referenced this issue Apr 29, 2024
Running a lot of VK CTS in parallel against nouveau, once every
few hours you might see something like this crash.

BUG: kernel NULL pointer dereference, address: 0000000000000008
PGD 8000000114e6e067 P4D 8000000114e6e067 PUD 109046067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 7 PID: 53891 Comm: deqp-vk Not tainted 6.8.0-rc6+ #27
Hardware name: Gigabyte Technology Co., Ltd. Z390 I AORUS PRO WIFI/Z390 I AORUS PRO WIFI-CF, BIOS F8 11/05/2021
RIP: 0010:gp100_vmm_pgt_mem+0xe3/0x180 [nouveau]
Code: c7 48 01 c8 49 89 45 58 85 d2 0f 84 95 00 00 00 41 0f b7 46 12 49 8b 7e 08 89 da 42 8d 2c f8 48 8b 47 08 41 83 c7 01 48 89 ee <48> 8b 40 08 ff d0 0f 1f 00 49 8b 7e 08 48 89 d9 48 8d 75 04 48 c1
RSP: 0000:ffffac20c5857838 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 00000000004d8001 RCX: 0000000000000001
RDX: 00000000004d8001 RSI: 00000000000006d8 RDI: ffffa07afe332180
RBP: 00000000000006d8 R08: ffffac20c5857ad0 R09: 0000000000ffff10
R10: 0000000000000001 R11: ffffa07af27e2de0 R12: 000000000000001c
R13: ffffac20c5857ad0 R14: ffffa07a96fe9040 R15: 000000000000001c
FS:  00007fe395eed7c0(0000) GS:ffffa07e2c980000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 000000011febe001 CR4: 00000000003706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

...

 ? gp100_vmm_pgt_mem+0xe3/0x180 [nouveau]
 ? gp100_vmm_pgt_mem+0x37/0x180 [nouveau]
 nvkm_vmm_iter+0x351/0xa20 [nouveau]
 ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau]
 ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
 ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
 ? __lock_acquire+0x3ed/0x2170
 ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
 nvkm_vmm_ptes_get_map+0xc2/0x100 [nouveau]
 ? __pfx_nvkm_vmm_ref_ptes+0x10/0x10 [nouveau]
 ? __pfx_gp100_vmm_pgt_mem+0x10/0x10 [nouveau]
 nvkm_vmm_map_locked+0x224/0x3a0 [nouveau]

Adding any sort of useful debug usually makes it go away, so I hand
wrote the function in a line, and debugged the asm.

Every so often pt->memory->ptrs is NULL. This ptrs ptr is set in
the nv50_instobj_acquire called from nvkm_kmap.

If Thread A and Thread B both get to nv50_instobj_acquire around
the same time, and Thread A hits the refcount_set line, and in
lockstep thread B succeeds at refcount_inc_not_zero, there is a
chance the ptrs value won't have been stored since refcount_set
is unordered. Force a memory barrier here, I picked smp_mb, since
we want it on all CPUs and it's write followed by a read.

v2: use paired smp_rmb/smp_wmb.

Cc: <stable@vger.kernel.org>
Fixes: be55287 ("drm/nouveau/imem/nv50: embed nvkm_instobj directly into nv04_instobj")
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240411011510.2546857-1-airlied@gmail.com
ojeda pushed a commit that referenced this issue May 27, 2024
When request_irq() fails, error path calls vp_del_vqs(). There, as vq is
present in the list, free_irq() is called for the same vector. That
causes following splat:

[    0.414355] Trying to free already-free IRQ 27
[    0.414403] WARNING: CPU: 1 PID: 1 at kernel/irq/manage.c:1899 free_irq+0x1a1/0x2d0
[    0.414510] Modules linked in:
[    0.414540] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.9.0-rc4+ #27
[    0.414540] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014
[    0.414540] RIP: 0010:free_irq+0x1a1/0x2d0
[    0.414540] Code: 1e 00 48 83 c4 08 48 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 90 8b 74 24 04 48 c7 c7 98 80 6c b1 e8 00 c9 f7 ff 90 <0f> 0b 90 90 48 89 ee 4c 89 ef e8 e0 20 b8 00 49 8b 47 40 48 8b 40
[    0.414540] RSP: 0000:ffffb71480013ae0 EFLAGS: 00010086
[    0.414540] RAX: 0000000000000000 RBX: ffffa099c2722000 RCX: 0000000000000000
[    0.414540] RDX: 0000000000000000 RSI: ffffb71480013998 RDI: 0000000000000001
[    0.414540] RBP: 0000000000000246 R08: 00000000ffffdfff R09: 0000000000000001
[    0.414540] R10: 00000000ffffdfff R11: ffffffffb18729c0 R12: ffffa099c1c91760
[    0.414540] R13: ffffa099c1c916a4 R14: ffffa099c1d2f200 R15: ffffa099c1c91600
[    0.414540] FS:  0000000000000000(0000) GS:ffffa099fec40000(0000) knlGS:0000000000000000
[    0.414540] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.414540] CR2: 0000000000000000 CR3: 0000000008e3e001 CR4: 0000000000370ef0
[    0.414540] Call Trace:
[    0.414540]  <TASK>
[    0.414540]  ? __warn+0x80/0x120
[    0.414540]  ? free_irq+0x1a1/0x2d0
[    0.414540]  ? report_bug+0x164/0x190
[    0.414540]  ? handle_bug+0x3b/0x70
[    0.414540]  ? exc_invalid_op+0x17/0x70
[    0.414540]  ? asm_exc_invalid_op+0x1a/0x20
[    0.414540]  ? free_irq+0x1a1/0x2d0
[    0.414540]  vp_del_vqs+0xc1/0x220
[    0.414540]  vp_find_vqs_msix+0x305/0x470
[    0.414540]  vp_find_vqs+0x3e/0x1a0
[    0.414540]  vp_modern_find_vqs+0x1b/0x70
[    0.414540]  init_vqs+0x387/0x600
[    0.414540]  virtnet_probe+0x50a/0xc80
[    0.414540]  virtio_dev_probe+0x1e0/0x2b0
[    0.414540]  really_probe+0xc0/0x2c0
[    0.414540]  ? __pfx___driver_attach+0x10/0x10
[    0.414540]  __driver_probe_device+0x73/0x120
[    0.414540]  driver_probe_device+0x1f/0xe0
[    0.414540]  __driver_attach+0x88/0x180
[    0.414540]  bus_for_each_dev+0x85/0xd0
[    0.414540]  bus_add_driver+0xec/0x1f0
[    0.414540]  driver_register+0x59/0x100
[    0.414540]  ? __pfx_virtio_net_driver_init+0x10/0x10
[    0.414540]  virtio_net_driver_init+0x90/0xb0
[    0.414540]  do_one_initcall+0x58/0x230
[    0.414540]  kernel_init_freeable+0x1a3/0x2d0
[    0.414540]  ? __pfx_kernel_init+0x10/0x10
[    0.414540]  kernel_init+0x1a/0x1c0
[    0.414540]  ret_from_fork+0x31/0x50
[    0.414540]  ? __pfx_kernel_init+0x10/0x10
[    0.414540]  ret_from_fork_asm+0x1a/0x30
[    0.414540]  </TASK>

Fix this by calling deleting the current vq when request_irq() fails.

Fixes: 0b0f9dc ("Revert "virtio_pci: use shared interrupts for virtqueues"")
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Message-Id: <20240426150845.3999481-1-jiri@resnulli.us>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This issue was closed.
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