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Fix linux-raw inline asm for thumb-mode. (#416)
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* Fix linux-raw inline asm for thumb-mode.

In thumb-mode, r7 is reserved as the frame pointer and isn't permitted
as an inline asm operand. It's still the syscall-number operand in
syscalls though, so pass the syscall-number operand in in a separate
register, copy it into r7 inside the inline asm, and then restore the
value of r7 when we're done.

* Add a thumbv7neon-unknown-linux-gnueabihf line to CI.
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@sunfishcode
sunfishcode committed Sep 27, 2022
1 parent 08773a6 commit ebf562f
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2 changes: 2 additions & 0 deletions .github/workflows/main.yml
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Expand Up @@ -163,8 +163,10 @@ jobs:
rustup target add
x86_64-unknown-redox
wasm32-wasi
thumbv7neon-unknown-linux-gnueabihf
- run: cargo check --workspace --release -vv --target=x86_64-unknown-redox --features=all-apis
- run: cargo check --workspace --release -vv --target=wasm32-wasi --features=all-apis
- run: cargo check --workspace --release -vv --target=thumbv7neon-unknown-linux-gnueabihf --features=all-apis

check_tier3:
name: Check selected Tier 3 platforms
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9 changes: 8 additions & 1 deletion src/backend/linux_raw/arch/inline/mod.rs
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Expand Up @@ -5,7 +5,14 @@
//! conventions are otherwise the compiler's job. But for now, use inline asm.

#[cfg_attr(target_arch = "aarch64", path = "aarch64.rs")]
#[cfg_attr(target_arch = "arm", path = "arm.rs")]
#[cfg_attr(
all(target_arch = "arm", not(target_feature = "thumb-mode")),
path = "arm.rs"
)]
#[cfg_attr(
all(target_arch = "arm", target_feature = "thumb-mode"),
path = "thumb.rs"
)]
#[cfg_attr(target_arch = "mips", path = "mips.rs")]
#[cfg_attr(target_arch = "mips64", path = "mips64.rs")]
#[cfg_attr(target_arch = "powerpc64", path = "powerpc64.rs")]
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322 changes: 322 additions & 0 deletions src/backend/linux_raw/arch/inline/thumb.rs
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@@ -0,0 +1,322 @@
//! arm Linux system calls, using thumb-mode.
//!
//! In thumb-mode, r7 is the frame pointer and is not permitted to be used in
//! an inline asm operand, so we have to use a different register and copy it
//! into r7 inside the inline asm.

use crate::backend::reg::{
ArgReg, FromAsm, RetReg, SyscallNumber, ToAsm, A0, A1, A2, A3, A4, A5, R0,
};
use core::arch::asm;

#[inline]
pub(in crate::backend) unsafe fn syscall0_readonly(nr: SyscallNumber<'_>) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
lateout("r0") r0,
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall1(nr: SyscallNumber<'_>, a0: ArgReg<'_, A0>) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall1_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall1_noreturn(nr: SyscallNumber<'_>, a0: ArgReg<'_, A0>) -> ! {
asm!(
"mov r7, {nr}",
"svc 0",
nr = in(reg) nr.to_asm(),
in("r0") a0.to_asm(),
options(noreturn)
)
}

#[inline]
pub(in crate::backend) unsafe fn syscall2(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall2_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall3(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall3_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall4(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall4_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall5(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
in("r4") a4.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall5_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
in("r4") a4.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall6(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
a5: ArgReg<'_, A5>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
in("r4") a4.to_asm(),
in("r5") a5.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}

#[inline]
pub(in crate::backend) unsafe fn syscall6_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
a5: ArgReg<'_, A5>,
) -> RetReg<R0> {
let r0;
asm!(
"mov {tmp}, r7",
"mov r7, {nr}",
"svc 0",
"mov r7, {tmp}",
nr = in(reg) nr.to_asm(),
tmp = out(reg) _,
inlateout("r0") a0.to_asm() => r0,
in("r1") a1.to_asm(),
in("r2") a2.to_asm(),
in("r3") a3.to_asm(),
in("r4") a4.to_asm(),
in("r5") a5.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}

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