linux-kernel - Re: [PATCH v2 1/5] x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust

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Message-ID: <20241218110408.GF2484@noisy.programming.kicks-ass.net>
Date: Wed, 18 Dec 2024 12:04:08 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: FUJITA Tomonori <fujita.tomonori@...il.com>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
	x86@...nel.org, linux-riscv@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, loongarch@...ts.linux.dev,
	tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, hpa@...or.com,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	catalin.marinas@....com, will@...nel.org, chenhuacai@...nel.org,
	kernel@...0n.name, tangyouling@...ngson.cn, hejinyang@...ngson.cn,
	yangtiezhu@...ngson.cn, ojeda@...nel.org, alex.gaynor@...il.com,
	boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com,
	benno.lossin@...ton.me, a.hindborg@...nel.org, aliceryhl@...gle.com,
	tmgross@...ch.edu
Subject: Re: [PATCH v2 1/5] x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm
 code sharing with Rust

On Wed, Dec 18, 2024 at 03:20:05PM +0900, FUJITA Tomonori wrote:
> Add new ARCH_WARN_ASM macro for BUG/WARN assembly code sharing with
> Rust to avoid the duplication.

This conflicts with some patches I've been sitting on, but nothing that
I can't resolve I think.

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>

> Signed-off-by: FUJITA Tomonori <fujita.tomonori@...il.com>
> ---
>  arch/x86/include/asm/bug.h | 51 ++++++++++++++++++--------------------
>  1 file changed, 24 insertions(+), 27 deletions(-)
> 
> diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
> index 806649c7f23d..71df68e2a731 100644
> --- a/arch/x86/include/asm/bug.h
> +++ b/arch/x86/include/asm/bug.h
> @@ -28,45 +28,42 @@
>  #ifdef CONFIG_GENERIC_BUG
>  
>  #ifdef CONFIG_X86_32
> -# define __BUG_REL(val)	".long " __stringify(val)
> +# define __BUG_REL(val)	".long " val
>  #else
> -# define __BUG_REL(val)	".long " __stringify(val) " - ."
> +# define __BUG_REL(val)	".long " val " - ."
>  #endif
>  
>  #ifdef CONFIG_DEBUG_BUGVERBOSE
> +#define __BUG_ENTRY(file, line, flags)					\
> +	"2:\t" __BUG_REL("1b") "\t# bug_entry::bug_addr\n"		\
> +	"\t" __BUG_REL(file)   "\t# bug_entry::file\n"			\
> +	"\t.word " line        "\t# bug_entry::line\n"			\
> +	"\t.word " flags       "\t# bug_entry::flags\n"
> +#else
> +#define __BUG_ENTRY(file, ine, flags)					\
> +	"2:\t" __BUG_REL("1b") "\t# bug_entry::bug_addr\n"		\
> +	"\t.word " flags       "\t# bug_entry::flags\n"
> +#endif
> +
> +#define _BUG_FLAGS_ASM(ins, file, line, flags, size, extra)		\
> +	"1:\t" ins "\n"							\
> +	".pushsection __bug_table,\"aw\"\n"				\
> +	__BUG_ENTRY(file, line, flags)					\
> +	"\t.org 2b + " size "\n"					\
> +	".popsection\n"							\
> +	extra
>  
>  #define _BUG_FLAGS(ins, flags, extra)					\
>  do {									\
> -	asm_inline volatile("1:\t" ins "\n"				\
> -		     ".pushsection __bug_table,\"aw\"\n"		\
> -		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
> -		     "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"	\
> -		     "\t.word %c1"        "\t# bug_entry::line\n"	\
> -		     "\t.word %c2"        "\t# bug_entry::flags\n"	\
> -		     "\t.org 2b+%c3\n"					\
> -		     ".popsection\n"					\
> -		     extra						\
> +	asm_inline volatile(_BUG_FLAGS_ASM(ins, "%c0",			\
> +					   "%c1", "%c2", "%c3", extra)	\
>  		     : : "i" (__FILE__), "i" (__LINE__),		\
>  			 "i" (flags),					\
>  			 "i" (sizeof(struct bug_entry)));		\
>  } while (0)
>  
> -#else /* !CONFIG_DEBUG_BUGVERBOSE */
> -
> -#define _BUG_FLAGS(ins, flags, extra)					\
> -do {									\
> -	asm_inline volatile("1:\t" ins "\n"				\
> -		     ".pushsection __bug_table,\"aw\"\n"		\
> -		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
> -		     "\t.word %c0"        "\t# bug_entry::flags\n"	\
> -		     "\t.org 2b+%c1\n"					\
> -		     ".popsection\n"					\
> -		     extra						\
> -		     : : "i" (flags),					\
> -			 "i" (sizeof(struct bug_entry)));		\
> -} while (0)
> -
> -#endif /* CONFIG_DEBUG_BUGVERBOSE */
> +#define ARCH_WARN_ASM(file, line, flags, size)				\
> +	_BUG_FLAGS_ASM(ASM_UD2, file, line, flags, size, "")
>  
>  #else
>  
> -- 
> 2.43.0
> 
>