[PATCH 6.12/6.13] loongarch: Use ASM_REACHABLE

[PATCH 6.12/6.13] loongarch: Use ASM_REACHABLE

[Huacai Chen]

From: Peter Zijlstra <peterz@infradead.org>

commit 624bde3465f660e54a7cd4c1efc3e536349fead5 upstream.

annotate_reachable() is unreliable since the compiler is free to place
random code inbetween two consecutive asm() statements.

This removes the last and only annotate_reachable() user.

Backport to solve a build error since relevant commits have already been
backported.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.133437051@infradead.org
Closes: https://lore.kernel.org/loongarch/20250307214943.372210-1-ojeda@kernel.org/
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/bug.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index 08388876ade4..561ac1bf79e2 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -4,6 +4,7 @@
 
 #include <asm/break.h>
 #include <linux/stringify.h>
+#include <linux/objtool.h>
 
 #ifndef CONFIG_DEBUG_BUGVERBOSE
 #define _BUGVERBOSE_LOCATION(file, line)
@@ -33,25 +34,25 @@
 
 #define ASM_BUG_FLAGS(flags)					\
 	__BUG_ENTRY(flags)					\
-	break		BRK_BUG
+	break		BRK_BUG;
 
 #define ASM_BUG()	ASM_BUG_FLAGS(0)
 
-#define __BUG_FLAGS(flags)					\
-	asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags)));
+#define __BUG_FLAGS(flags, extra)					\
+	asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags))		\
+			     extra);
 
 #define __WARN_FLAGS(flags)					\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(BUGFLAG_WARNING|(flags));			\
-	annotate_reachable();					\
+	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ASM_REACHABLE);	\
 	instrumentation_end();					\
 } while (0)
 
 #define BUG()							\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(0);						\
+	__BUG_FLAGS(0, "");					\
 	unreachable();						\
 } while (0)
 
-- 
2.47.1

Re: [PATCH 6.12/6.13] loongarch: Use ASM_REACHABLE

[Miguel Ojeda]

On Sat, 08 Mar 2025 13:37:53 +0800 Huacai Chen <chenhuacai@loongson.cn> wrote:
>
> From: Peter Zijlstra <peterz@infradead.org>
>
> commit 624bde3465f660e54a7cd4c1efc3e536349fead5 upstream.
>
> annotate_reachable() is unreliable since the compiler is free to place
> random code inbetween two consecutive asm() statements.
>
> This removes the last and only annotate_reachable() user.
>
> Backport to solve a build error since relevant commits have already been
> backported.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
> Link: https://lore.kernel.org/r/20241128094312.133437051@infradead.org
> Closes: https://lore.kernel.org/loongarch/20250307214943.372210-1-ojeda@kernel.org/
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

This indeed removes the build failure for me -- built-tested for loongarch64
(together with the rest of the Rust long backport series):

Tested-by: Miguel Ojeda <ojeda@kernel.org>

Thanks!

Cheers,
Miguel

Re: [PATCH 6.12/6.13] loongarch: Use ASM_REACHABLE

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 624bde3465f660e54a7cd4c1efc3e536349fead5

WARNING: Author mismatch between patch and upstream commit:
Backport author: Huacai Chen<chenhuacai@loongson.cn>
Commit author: Peter Zijlstra<peterz@infradead.org>

Status in newer kernel trees:
6.13.y | Present (different SHA1: 92a3a4ad5be7)
6.6.y | Not found

Note: The patch differs from the upstream commit:
---
1:  624bde3465f66 ! 1:  0911995aac2a8 loongarch: Use ASM_REACHABLE
    @@ Metadata
      ## Commit message ##
         loongarch: Use ASM_REACHABLE
     
    +    commit 624bde3465f660e54a7cd4c1efc3e536349fead5 upstream.
    +
         annotate_reachable() is unreliable since the compiler is free to place
         random code inbetween two consecutive asm() statements.
     
         This removes the last and only annotate_reachable() user.
     
    +    Backport to solve a build error since relevant commits have already been
    +    backported.
    +
         Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
         Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
         Link: https://lore.kernel.org/r/20241128094312.133437051@infradead.org
    +    Closes: https://lore.kernel.org/loongarch/20250307214943.372210-1-ojeda@kernel.org/
    +    Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
     
      ## arch/loongarch/include/asm/bug.h ##
     @@
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Success    |  Success   |
| stable/linux-6.13.y       |  Success    |  Success   |