* [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
@ 2026-08-19 8:48 ` Mukesh Kumar Chaurasiya (IBM)
0 siblings, 0 replies; 8+ messages in thread
From: Mukesh Kumar Chaurasiya (IBM) @ 2026-08-19 8:48 UTC (permalink / raw)
To: maddy, mpe, npiggin, chleroy, pjw, palmer, aou, alex, ojeda,
boqun, gary, bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross,
dakr, daniel.almeida, tamird, acourbot, work, thuth, mkchauras,
linuxppc-dev, linux-kernel, linux-riscv, rust-for-linux
Cc: FUJITA Tomonori
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 <tomo@flapping.org>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
---
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
--
2.55.0
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^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
2026-08-19 8:48 ` Mukesh Kumar Chaurasiya (IBM)
@ 2026-08-19 10:02 ` Miguel Ojeda
-1 siblings, 0 replies; 8+ messages in thread
From: Miguel Ojeda @ 2026-08-19 10:02 UTC (permalink / raw)
To: Mukesh Kumar Chaurasiya (IBM)
Cc: maddy, mpe, npiggin, chleroy, pjw, palmer, aou, alex, ojeda,
boqun, gary, bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross,
dakr, daniel.almeida, tamird, acourbot, work, thuth, linuxppc-dev,
linux-kernel, linux-riscv, rust-for-linux, FUJITA Tomonori
On Wed, Aug 19, 2026 at 10:48 AM Mukesh Kumar Chaurasiya (IBM)
<mkchauras@gmail.com> wrote:
>
> 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 <tomo@flapping.org>
Should this be Reported-by?
In addition, probably we want a Link to the original report, and a Fixes tag.
Ideally, please include the error message in the commit message -- it
helps to triaging and also to search it later on etc.
Thanks!
Cheers,
Miguel
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
@ 2026-08-19 10:02 ` Miguel Ojeda
0 siblings, 0 replies; 8+ messages in thread
From: Miguel Ojeda @ 2026-08-19 10:02 UTC (permalink / raw)
To: Mukesh Kumar Chaurasiya (IBM)
Cc: maddy, mpe, npiggin, chleroy, pjw, palmer, aou, alex, ojeda,
boqun, gary, bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross,
dakr, daniel.almeida, tamird, acourbot, work, thuth, linuxppc-dev,
linux-kernel, linux-riscv, rust-for-linux, FUJITA Tomonori
On Wed, Aug 19, 2026 at 10:48 AM Mukesh Kumar Chaurasiya (IBM)
<mkchauras@gmail.com> wrote:
>
> 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 <tomo@flapping.org>
Should this be Reported-by?
In addition, probably we want a Link to the original report, and a Fixes tag.
Ideally, please include the error message in the commit message -- it
helps to triaging and also to search it later on etc.
Thanks!
Cheers,
Miguel
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
2026-08-19 10:02 ` Miguel Ojeda
@ 2026-08-19 10:42 ` Mukesh Kumar Chaurasiya
-1 siblings, 0 replies; 8+ messages in thread
From: Mukesh Kumar Chaurasiya @ 2026-08-19 10:42 UTC (permalink / raw)
To: Miguel Ojeda
Cc: maddy, mpe, npiggin, chleroy, pjw, palmer, aou, alex, ojeda,
boqun, gary, bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross,
dakr, daniel.almeida, tamird, acourbot, work, thuth, linuxppc-dev,
linux-kernel, linux-riscv, rust-for-linux, FUJITA Tomonori
On Wed, Aug 19, 2026 at 12:02:01PM +0200, Miguel Ojeda wrote:
> On Wed, Aug 19, 2026 at 10:48 AM Mukesh Kumar Chaurasiya (IBM)
> <mkchauras@gmail.com> wrote:
> >
> > 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 <tomo@flapping.org>
>
> Should this be Reported-by?
>
The change itself is suggested by Tomonori so i was not sure.
Yeah there should be
Reported-by: Link Mauve <linkmauve@linkmauve.fr>
Closes: https://lore.kernel.org/all/anG67Q6Y59kDqh-c@desktop
Fixes: 73b741adb264 ("rust: Add PowerPC support")
> In addition, probably we want a Link to the original report, and a Fixes tag.
>
> Ideally, please include the error message in the commit message -- it
> helps to triaging and also to search it later on etc.
>
Sure i'll add the error to the commit message and send out a new
revision.
> Thanks!
>
> Cheers,
> Miguel
Thanks for the quick review.
Regards,
Mukesh
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
@ 2026-08-19 10:42 ` Mukesh Kumar Chaurasiya
0 siblings, 0 replies; 8+ messages in thread
From: Mukesh Kumar Chaurasiya @ 2026-08-19 10:42 UTC (permalink / raw)
To: Miguel Ojeda
Cc: maddy, mpe, npiggin, chleroy, pjw, palmer, aou, alex, ojeda,
boqun, gary, bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross,
dakr, daniel.almeida, tamird, acourbot, work, thuth, linuxppc-dev,
linux-kernel, linux-riscv, rust-for-linux, FUJITA Tomonori
On Wed, Aug 19, 2026 at 12:02:01PM +0200, Miguel Ojeda wrote:
> On Wed, Aug 19, 2026 at 10:48 AM Mukesh Kumar Chaurasiya (IBM)
> <mkchauras@gmail.com> wrote:
> >
> > 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 <tomo@flapping.org>
>
> Should this be Reported-by?
>
The change itself is suggested by Tomonori so i was not sure.
Yeah there should be
Reported-by: Link Mauve <linkmauve@linkmauve.fr>
Closes: https://lore.kernel.org/all/anG67Q6Y59kDqh-c@desktop
Fixes: 73b741adb264 ("rust: Add PowerPC support")
> In addition, probably we want a Link to the original report, and a Fixes tag.
>
> Ideally, please include the error message in the commit message -- it
> helps to triaging and also to search it later on etc.
>
Sure i'll add the error to the commit message and send out a new
revision.
> Thanks!
>
> Cheers,
> Miguel
Thanks for the quick review.
Regards,
Mukesh
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
2026-08-19 8:48 ` Mukesh Kumar Chaurasiya (IBM)
@ 2026-08-19 11:50 ` Christophe Leroy (CS GROUP)
-1 siblings, 0 replies; 8+ messages in thread
From: Christophe Leroy (CS GROUP) @ 2026-08-19 11:50 UTC (permalink / raw)
To: Mukesh Kumar Chaurasiya (IBM), maddy, mpe, npiggin, pjw, palmer,
aou, alex, ojeda, boqun, gary, bjorn3_gh, lossin, a.hindborg,
aliceryhl, tmgross, dakr, daniel.almeida, tamird, acourbot, work,
thuth, linuxppc-dev, linux-kernel, linux-riscv, rust-for-linux
Cc: FUJITA Tomonori
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 <tomo@flapping.org>
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
> ---
> 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
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] powerpc/bug: Add ARCH_WARN_ASM and refactor _EMIT_BUG_ENTRY for Rust support
@ 2026-08-19 11:50 ` Christophe Leroy (CS GROUP)
0 siblings, 0 replies; 8+ messages in thread
From: Christophe Leroy (CS GROUP) @ 2026-08-19 11:50 UTC (permalink / raw)
To: Mukesh Kumar Chaurasiya (IBM), maddy, mpe, npiggin, pjw, palmer,
aou, alex, ojeda, boqun, gary, bjorn3_gh, lossin, a.hindborg,
aliceryhl, tmgross, dakr, daniel.almeida, tamird, acourbot, work,
thuth, linuxppc-dev, linux-kernel, linux-riscv, rust-for-linux
Cc: FUJITA Tomonori
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 <tomo@flapping.org>
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
> ---
> 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
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^ permalink raw reply [flat|nested] 8+ messages in thread