Commit-ID: 45c39fb0cc20d24da08d5bb159f57d191098104d Gitweb: http://git.kernel.org/tip/45c39fb0cc20d24da08d5bb159f57d191098104d Author: H. Peter Anvin <[email protected]> AuthorDate: Wed, 28 Nov 2012 11:50:30 -0800 Committer: H. Peter Anvin <[email protected]> CommitDate: Thu, 29 Nov 2012 13:25:39 -0800
x86, cleanups: Simplify sync_core() in the case of no CPUID Simplify the implementation of sync_core() for the case where we may not have the CPUID instruction available. [ v2: stylistic cleanup of the #else clause per suggestion by Borislav Petkov. ] Signed-off-by: H. Peter Anvin <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Cc: Borislav Petkov <[email protected]> --- arch/x86/include/asm/processor.h | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 9a4ee46..b0d3e73 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -673,17 +673,28 @@ static inline void sync_core(void) int tmp; #ifdef CONFIG_M486 - if (boot_cpu_data.x86 < 5) - /* There is no speculative execution. - * jmp is a barrier to prefetching. */ - asm volatile("jmp 1f\n1:\n" ::: "memory"); - else + /* + * Do a CPUID if available, otherwise do a jump. The jump + * can conveniently enough be the jump around CPUID. + */ + asm volatile("cmpl %2,%1\n\t" + "jl 1f\n\t" + "cpuid\n" + "1:" + : "=a" (tmp) + : "rm" (boot_cpu_data.cpuid_level), "ri" (0), "0" (1) + : "ebx", "ecx", "edx", "memory"); +#else + /* + * CPUID is a barrier to speculative execution. + * Prefetched instructions are automatically + * invalidated when modified. + */ + asm volatile("cpuid" + : "=a" (tmp) + : "0" (1) + : "ebx", "ecx", "edx", "memory"); #endif - /* cpuid is a barrier to speculative execution. - * Prefetched instructions are automatically - * invalidated when modified. */ - asm volatile("cpuid" : "=a" (tmp) : "0" (1) - : "ebx", "ecx", "edx", "memory"); } static inline void __monitor(const void *eax, unsigned long ecx, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
