linux-kernel - Re: [PATCH 1/7] Add conditional oopsing with annotation

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Message-Id: <201112171415.57601.vapier@gentoo.org>
Date:	Sat, 17 Dec 2011 14:15:55 -0500
From:	Mike Frysinger <vapier@...too.org>
To:	David Howells <dhowells@...hat.com>
Cc:	linux-arch@...r.kernel.org, mingo@...e.hu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] Add conditional oopsing with annotation

On Friday 16 December 2011 09:13:57 David Howells wrote:
> --- a/arch/x86/include/asm/bug.h
> +++ b/arch/x86/include/asm/bug.h
> 
> +extern const void __arch_annotated_bug;
> +#define arch_annotated_bug(desc)				\
> +	do {							\
> +		asm volatile(".globl __arch_annotated_bug\n"	\
> +			     "__arch_annotated_bug:\n"		\
> +			     "	ud2\n"				\
> +			     : : "d" (desc));			\
> +		unreachable();					\
> +	} while (0)
> +
> +#define is_arch_annotated_bug(regs)					\
> +	({ ((const void *)regs->ip == &__arch_annotated_bug) ?		\
> +			(struct annotated_bug *)regs->dx : NULL; })

seems like this is making arches duplicate a bit of logic they shouldn't have 
to ... you could have asm-generic/bug.h do:

#ifdef arch_annotated_bug_fail

extern const void __arch_annotated_bug;
# define ARCH_ANNOTATED_SYM_STR CONFIG_SYMBOL_PREFIX"__arch_annotated_bug"

# define arch_annotated_bug(desc) \
	do { \
		asm volatile(".globl " ARCH_ANNOTATED_SYM ";\n" \
			ARCH_ANNOTATED_SYM_STR":\n"); \
		arch_annotated_bug_fail(desc) ; \
		unreachable(); \
	} while (0)

# define is_arch_annotated_bug(regs) \
	({ (instruction_pointer(regs) == &__arch_annotated_bug) ? \
		(struct annotated_bug *)arch_annotated_bug_struct(regs) : \
		NULL; })

#endif

so now arches have to define two small bits.  in the x86 case:
#define arch_annotated_bug_fail(desc) asm volatile("ud2;" : : "d" (desc))
#define arch_annotated_bug_struct(regs) (regs)->dx
-mike

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