Le 10/09/2026 à 09:12, Mukesh Kumar Chaurasiya (IBM) a écrit :
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
```
Refactor _EMIT_BUG_ENTRY to accept explicit (file, line, flags) string
arguments rather than relying on positional asm operand references
(%0, %1, %2, %3). This allows the macro to be composed as a plain
string concatenation, which is required for ARCH_WARN_ASM where no asm
operand context exists.
For a cleaner _EMIT_BUG_ENTRY() macro, shouldn't it also pass the label
where the trap sits as a macro argument instead of blindly relying on it
being 1: ?
Christophe
Move the .org and .previous directives out of _EMIT_BUG_ENTRY and into
the BUG_ENTRY() call site to preserve existing behaviour while enabling
ARCH_WARN_ASM to supply its own size operand 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 <[email protected]>
Closes: https://lore.kernel.org/all/anG67Q6Y59kDqh-c@desktop
Fixes: 73b741adb264 ("rust: Add PowerPC support")
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <[email protected]>
---
Changelog:
V1 -> V2:
- commit message now has error, fixes tag and closes tag
arch/powerpc/include/asm/bug.h | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index 0db48977c70c..8aba39e0cf26 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -32,34 +32,38 @@
#endif /* verbose */
#else /* !__ASSEMBLER__ */
-/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
- sizeof(struct bug_entry), respectively */
#ifdef CONFIG_DEBUG_BUGVERBOSE
-#define _EMIT_BUG_ENTRY \
+#define _EMIT_BUG_ENTRY(file, line, flags) \
".section __bug_table,\"aw\"\n" \
"2: .4byte 1b - .\n" \
- " .4byte %0 - .\n" \
- " .short %1, %2\n" \
- ".org 2b+%3\n" \
- ".previous\n"
+ " .4byte " file " - .\n" \
+ " .short " line ", " flags "\n"
#else
-#define _EMIT_BUG_ENTRY \
+#define _EMIT_BUG_ENTRY(file, line, flags) \
".section __bug_table,\"aw\"\n" \
"2: .4byte 1b - .\n" \
- " .short %2\n" \
- ".org 2b+%3\n" \
- ".previous\n"
+ " .short " flags "\n"
#endif
#define BUG_ENTRY(cond_str, insn, flags, ...) \
__asm__ __volatile__( \
"1: " insn "\n" \
- _EMIT_BUG_ENTRY \
+ _EMIT_BUG_ENTRY("%0", "%1", "%2") \
+ ".org 2b+%3\n" \
+ ".previous\n" \
: : "i" (WARN_CONDITION_STR(cond_str) __FILE__), "i"
(__LINE__), \
"i" (flags), \
"i" (sizeof(struct bug_entry)), \
##__VA_ARGS__)
+#define ARCH_WARN_ASM(file, line, flags, size) \
+ "1: twi 31, 0, 0\n" \
+ _EMIT_BUG_ENTRY(file, line, flags) \
+ ".org 2b+" size "\n" \
+ ".previous\n"
+
+#define ARCH_WARN_REACHABLE
+
/*
* BUG_ON() and WARN_ON() do their best to cooperate with compile-time
* optimisations. However depending on the complexity of the condition
