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authorH. Peter Anvin <hpa@linux.intel.com>2012-11-28 11:50:30 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2012-11-29 13:25:39 -0800
commit45c39fb0cc20d24da08d5bb159f57d191098104d (patch)
tree9ec9db8c7b9fa46d383b0c7dd4fe5339b577dfe6 /arch/x86/include/asm/processor.h
parente3228cf4544355f73437a2b9c6916be9cbafc201 (diff)
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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/processor.h')
-rw-r--r--arch/x86/include/asm/processor.h31
1 files 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,
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