diff options
Diffstat (limited to 'arch/x86/include/asm/processor.h')
| -rw-r--r-- | arch/x86/include/asm/processor.h | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index db0d8c32090..e101b38912d 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -672,18 +672,29 @@ static inline void sync_core(void) { int tmp; -#if defined(CONFIG_M386) || defined(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 +#ifdef CONFIG_M486 + /* + * 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, |