Le 19/08/2026 à 10:48, 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.
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.
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.
Suggested-by: FUJITA Tomonori <[email protected]>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <[email protected]>
---
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__ */
Sorry, I still don't understand. The only place the new macro is used is
a .S file (namely rust/kernel/generated_arch_warn_asm.rs.S), and the
change this patch implements is inside a #if !__ASSEMBLER__.
What am I missing ?
Christophe
-/* _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
