x86: Introduce barrier_nospec

[pandora-kernel.git] / arch / x86 / include / asm / system.h

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index 41fda4d..59567d1 100644 (file)
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -478,6 +478,10 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
 /* Override the default implementation from linux/nospec.h. */
 #define array_index_mask_nospec array_index_mask_nospec
 
+/* Prevent speculative execution past this barrier. */
+#define barrier_nospec() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \
+                                          "lfence", X86_FEATURE_LFENCE_RDTSC)
+
 /**
  * read_barrier_depends - Flush all pending reads that subsequents reads
  * depend on.
@@ -563,8 +567,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
  */
 static __always_inline void rdtsc_barrier(void)
 {
-       alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
-       alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
+       barrier_nospec();
 }
 
 /*