[PATCH] i386: Implement X86_FEATURE_SYNC_RDTSC on i386

Syncs up with x86-64.

Signed-off-by: Andi Kleen <ak@suse.de>

3 files changed, 4 insertions, 5 deletions

diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index 56fe26584957..dc4e08147b1f 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -188,8 +188,10 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
         }
 #endif
 
-        if (c->x86 == 15)
+        if (c->x86 == 15) {
                 set_bit(X86_FEATURE_P4, c->x86_capability);
+                set_bit(X86_FEATURE_SYNC_RDTSC, c->x86_capability);
+        }
         if (c->x86 == 6) 
                 set_bit(X86_FEATURE_P3, c->x86_capability);
         if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 20e849ae6ddc..b8a3a5a85fd3 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -79,6 +79,7 @@
 #define X86_FEATURE_PEBS        (3*32+12)  /* Precise-Event Based Sampling */
 #define X86_FEATURE_BTS         (3*32+13)  /* Branch Trace Store */
 #define X86_FEATURE_LAPIC_TIMER_BROKEN (3*32+ 14) /* lapic timer broken in C1 */
+#define X86_FEATURE_SYNC_RDTSC  (3*32+15)  /* RDTSC synchronizes the CPU */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3        (4*32+ 0) /* Streaming SIMD Extensions-3 */
diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
index 346976632e15..0181f9df7539 100644
--- a/include/asm-i386/tsc.h
+++ b/include/asm-i386/tsc.h
@@ -35,7 +35,6 @@ static inline cycles_t get_cycles(void)
 static __always_inline cycles_t get_cycles_sync(void)
 {
         unsigned long long ret;
-#ifdef X86_FEATURE_SYNC_RDTSC
         unsigned eax;
 
         /*
@@ -44,9 +43,6 @@ static __always_inline cycles_t get_cycles_sync(void)
          */
         alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
                           "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
-#else
-        sync_core();
-#endif
         rdtscll(ret);
 
         return ret;