diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2012-11-28 11:50:30 -0800 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-11-29 13:25:39 -0800 |
| commit | 45c39fb0cc20d24da08d5bb159f57d191098104d (patch) | |
| tree | 9ec9db8c7b9fa46d383b0c7dd4fe5339b577dfe6 /arch/x86/include/asm | |
| parent | e3228cf4544355f73437a2b9c6916be9cbafc201 (diff) | |
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 <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1354132230-21854-9-git-send-email-hpa@linux.intel.com
Cc: Borislav Petkov <bp@alien8.de>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/processor.h | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 9a4ee46959f..b0d3e736220 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, |