[PATCH] i386: i386 add Intel BTS cpufeature bit and detection (take 2)
Here is a small patch for i386 which adds a cpufeature flag and
detection code for Intel's Branch Trace Store (BTS) feature. This
feature can be found on Intel P4 and Core 2 processors among others.
It can also be used by perfmon.
changelog:
- add CPU_FEATURE_BTS
- add Branch Trace Store detection
signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index 3ae795e..56fe265 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -199,6 +199,8 @@
if (cpu_has_ds) {
unsigned int l1;
rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
+ if (!(l1 & (1<<11)))
+ set_bit(X86_FEATURE_BTS, c->x86_capability);
if (!(l1 & (1<<12)))
set_bit(X86_FEATURE_PEBS, c->x86_capability);
}
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 4c83e05..3f92b94 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -74,6 +74,7 @@
#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 */
+#define X86_FEATURE_BTS (3*32+13) /* Branch Trace Store */
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
#define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */
@@ -138,6 +139,7 @@
#define cpu_has_ds boot_cpu_has(X86_FEATURE_DS)
#define cpu_has_pebs boot_cpu_has(X86_FEATURE_PEBS)
#define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
+#define cpu_has_bts boot_cpu_has(X86_FEATURE_BTS)
#endif /* __ASM_I386_CPUFEATURE_H */