[PATCH] i386: i386 add X86_FEATURE_PEBS and detection

Here is a patch (used by perfmon2) to detect the presence of the Precise Event
Based Sampling (PEBS) feature for i386.  The patch also adds the cpu_has_pebs
macro.

- adds X86_FEATURE_PEBS

- adds cpu_has_pebs to test for X86_FEATURE_PEBS

Signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

2 files changed, 9 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index 94a95aa5227e..798c2f617e87 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -195,8 +195,14 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
         if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
                 (c->x86 == 0x6 && c->x86_model >= 0x0e))
                 set_bit(X86_FEATURE_CONSTANT_TSC, c->x86_capability);
-}
 
+        if (cpu_has_ds) {
+                unsigned int l1;
+                rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
+                if (!(l1 & (1<<12)))
+                        set_bit(X86_FEATURE_PEBS, c->x86_capability);
+        }
+}
 
 static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 * c, unsigned int size)
 {
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 69ce35049a07..231672558c1f 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -73,6 +73,7 @@
 #define X86_FEATURE_UP          (3*32+ 9) /* smp kernel running on up */
 #define X86_FEATURE_FXSAVE_LEAK (3*32+10) /* FXSAVE leaks FOP/FIP/FOP */
 #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */
+#define X86_FEATURE_PEBS        (3*32+12)  /* Precise-Event Based Sampling */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3        (4*32+ 0) /* Streaming SIMD Extensions-3 */
@@ -135,6 +136,7 @@
 #define cpu_has_pmm             boot_cpu_has(X86_FEATURE_PMM)
 #define cpu_has_pmm_enabled     boot_cpu_has(X86_FEATURE_PMM_EN)
 #define cpu_has_ds              boot_cpu_has(X86_FEATURE_DS)
+#define cpu_has_pebs            boot_cpu_has(X86_FEATURE_PEBS)
 
 #endif /* __ASM_I386_CPUFEATURE_H */