Define default .ra rules for PPC and ARM

[kuzaxak]

Breakpad CFI readers require a .ra rule at every unwindable address, but DWARF INIT rows can omit the return-address register rule. That leaves function entry CFI unusable even though the return address lives in a fixed register by ABI.

Add PowerPC register naming so LR can be emitted and use the CPU family to supply a default .ra on INIT rows for ARM, MIPS, and PowerPC when no explicit rule is present.

Based on my research, this is required for Arm32, Arm64, PPC.

Closes #948

[Dav1dde]

Thanks, looks good! Mind adding 1 or 2 integration tests to tests/?

[Dav1dde]

Fixed the unused import in the master branch, CI should pass if you update the branch.

[Dav1dde]

@kuzaxak can you add 1 or 2 tests to the integration tests for aarch64 (or other architectures)?

Or if you have rough instructions how to generate some test binaries, I can also look into it!

[kuzaxak]

@kuzaxak can you add 1 or 2 tests to the integration tests for aarch64 (or other architectures)?

Or if you have rough instructions how to generate some test binaries, I can also look into it!

@Dav1dde I was thinking to do it but I don't see a source code for the fixture app used in tests in the repo.

I can add a simple rust app that will be compiled into a binary and commit both.

[Dav1dde]

I can add a simple rust app that will be compiled into a binary and commit both.

That'd be awesome, but realizing we don't really have a good way setup to manage/generate these files. I guess I can just compile the files locally and check them in and in a follow-up think about a better organization.

[kuzaxak]

I can add a simple rust app that will be compiled into a binary and commit both.

That'd be awesome, but realizing we don't really have a good way setup to manage/generate these files. I guess I can just compile the files locally and check them in and in a follow-up think about a better organization.

@Dav1dde, yes, and I don't see a way to run these tests in the GHA right now, as I don't see an ARM runner.

[Dav1dde]

@kuzaxak I think easiest is just if I compile the binaries and check them in. The tests themselves should then not need an ARM runner as we just load the binaries.

If you have a test file I can compile that'd be helpful otherwise I'll just reserve some time and figure out something, just a lot of other stuff on my plate.

[kuzaxak]

@kuzaxak I think easiest is just if I compile the binaries and check them in. The tests themselves should then not need an ARM runner as we just load the binaries.

If you have a test file I can compile that'd be helpful otherwise I'll just reserve some time and figure out something, just a lot of other stuff on my plate.

@Dav1dde Added a commit with a simple C binary compiled to a binary, and based on it added a snapshot test.

Without a fix, it is failing:

---- cfi_from_elf_arm64 stdout ----
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Snapshot Summary ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Snapshot file: symbolic-cfi/tests/snapshots/test_cfi__cfi_elf_arm64.snap
Snapshot: cfi_elf_arm64
Source: symbolic-cfi/tests/test_cfi.rs:118
──────────────────────────────────────────────────────────────────────────────────────────────────────────
Expression: cfi
──────────────────────────────────────────────────────────────────────────────────────────────────────────
-old snapshot
+new results
────────────┬─────────────────────────────────────────────────────────────────────────────────────────────
    0       │-STACK CFI INIT 574 30 .cfa: sp 0 + .ra: x30
    1       │-STACK CFI INIT 5a4 3c .cfa: sp 0 + .ra: x30
    2       │-STACK CFI INIT 5e0 30 .cfa: sp 0 + .ra: x30
          0 │+STACK CFI INIT 574 30 .cfa: sp 0 +
          1 │+STACK CFI INIT 5a4 3c .cfa: sp 0 +
          2 │+STACK CFI INIT 5e0 30 .cfa: sp 0 +
    3     3 │ STACK CFI 5e4 .cfa: sp 32 + x29: .cfa -32 + ^ .ra: .cfa -24 + ^
    4     4 │ STACK CFI 5ec x19: .cfa -16 + ^
    5     5 │ STACK CFI 60c .cfa: sp 0 +
    6       │-STACK CFI INIT 610 4 .cfa: sp 0 + .ra: x30
    7       │-STACK CFI INIT 620 4 .cfa: sp 0 + .ra: x30
    8       │-STACK CFI INIT 624 8 .cfa: sp 0 + .ra: x30
    9       │-STACK CFI INIT 630 c .cfa: sp 0 + .ra: x30
   10       │-STACK CFI INIT 640 24 .cfa: sp 0 + .ra: x30
   11       │-STACK CFI INIT 510 8 .cfa: sp 0 + .ra: x30
   12       │-STACK CFI INIT 670 7c .cfa: sp 0 + .ra: x30
          6 │+STACK CFI INIT 610 4 .cfa: sp 0 +
          7 │+STACK CFI INIT 620 4 .cfa: sp 0 +
          8 │+STACK CFI INIT 624 8 .cfa: sp 0 +
          9 │+STACK CFI INIT 630 c .cfa: sp 0 +
         10 │+STACK CFI INIT 640 24 .cfa: sp 0 +
         11 │+STACK CFI INIT 510 8 .cfa: sp 0 +
         12 │+STACK CFI INIT 670 7c .cfa: sp 0 +
   13    13 │ STACK CFI 674 .cfa: sp 64 + x29: .cfa -64 + ^ .ra: .cfa -56 + ^
   14    14 │ STACK CFI 67c x19: .cfa -48 + ^ x20: .cfa -40 + ^
   15    15 │ STACK CFI 688 x21: .cfa -32 + ^ x22: .cfa -24 + ^
   16    16 │ STACK CFI 690 x23: .cfa -16 + ^ x24: .cfa -8 + ^
   17    17 │ STACK CFI 6e8 .cfa: sp 0 +
   18       │-STACK CFI INIT 6f0 4 .cfa: sp 0 + .ra: x30
         18 │+STACK CFI INIT 6f0 4 .cfa: sp 0 +
────────────┴─────────────────────────────────────────────────────────────────────────────────────────────
To update snapshots run `cargo insta review`
Stopped on the first failure. Run `cargo insta test` to run all snapshots.

[kuzaxak]

I think it is enough to consider the feature covered, WDYT?

[Dav1dde]

@kuzaxak thanks for the contribution, will merge after tests and release a new version