[PW_SID:1161965] [V3] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support - #2636
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[PW_SID:1161965] [V3] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support#2636linux-riscv-bot wants to merge 1 commit into
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…support
The Rust kernel infrastructure generates inline asm for WARN() via
ARCH_WARN_ASM(file, line, flags, size), expanding it through a C
preprocessor pass (generated_arch_warn_asm.rs.S) to produce an
arch-specific asm template string for use in Rust's core::arch macros.
powerpc currently lacks ARCH_WARN_ASM and ARCH_WARN_REACHABLE, causing
Rust builds to fail on powerpc with
```
error: no rules expected `ARCH_WARN_ASM`
--> /home/linkmauve/dev/linux/wii/rust/kernel/generated_arch_warn_asm.rs:1:28
|
1 | ::kernel::concat_literals!(ARCH_WARN_ASM("{file}", "{line}", "{flags}", "{size}"))
| ^^^^^^^^^^^^^ no rules expected this token in macro call
|
::: ../rust/kernel/lib.rs:279:1
|
279 | macro_rules! concat_literals {
| ---------------------------- when calling this macro
|
= note: while trying to match sequence start
error: no rules expected `ARCH_WARN_REACHABLE`
--> /home/linkmauve/dev/linux/wii/rust/kernel/generated_arch_reachable_asm.rs:1:28
|
1 | ::kernel::concat_literals!(ARCH_WARN_REACHABLE)
| ^^^^^^^^^^^^^^^^^^^ no rules expected this token in macro call
|
::: ../rust/kernel/lib.rs:279:1
|
279 | macro_rules! concat_literals {
| ---------------------------- when calling this macro
|
= note: while trying to match sequence start
error: aborting due to 2 previous errors
```
To add ARCH_WARN_ASM, _EMIT_BUG_ENTRY first needs to be refactored.
The old definition was a bare macro with no parameters, relying on
positional asm operand references (%0-%3), hardcoding the backward
reference to local label 1b, and including .org/.previous directives
inline. That made it impossible to compose as a plain string outside of
an asm operand context, and left an invisible contract that callers must
always emit their trap at label 1:.
Refactor _EMIT_BUG_ENTRY to take explicit (label, file, line, flags)
string arguments via string concatenation. This removes the dependency
on asm operand numbering and makes the trap label an explicit argument,
so the caller's intent is visible at the call site and a future caller
using a different label cannot silently produce a wrong bug table entry.
Move the .org and .previous directives out of _EMIT_BUG_ENTRY and into
each call site, so BUG_ENTRY() can still pass sizeof(struct bug_entry)
as an asm operand while ARCH_WARN_ASM can supply its own size string
independently.
Add ARCH_WARN_REACHABLE as an empty define, matching the arm64
convention, indicating that no additional reachability annotation is
needed after a WARN on powerpc.
This brings powerpc into line with x86, arm64, s390, and riscv, all of
which already define ARCH_WARN_ASM and ARCH_WARN_REACHABLE.
Reported-by: FUJITA Tomonori <tomo@flapping.org>
Closes: https://lore.kernel.org/all/anG67Q6Y59kDqh-c@desktop
Fixes: 73b741a ("rust: Add PowerPC support")
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>
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PR for series 1161965 applied to workflow__riscv__fixes
Name: [V3] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
URL: https://patchwork.kernel.org/series/1161965/
Version: 3