[PATCH] x86-64: x86-64 add Intel BTS cpufeature bit and detection (take 2)
Here is a small patch for x86-64 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/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 619af2e..a570c81 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -838,6 +838,8 @@
if (cpu_has_ds) {
unsigned int l1, l2;
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-x86_64/cpufeature.h b/include/asm-x86_64/cpufeature.h
index d280384..0b3c686 100644
--- a/include/asm-x86_64/cpufeature.h
+++ b/include/asm-x86_64/cpufeature.h
@@ -69,6 +69,7 @@
#define X86_FEATURE_UP (3*32+8) /* SMP kernel running on UP */
#define X86_FEATURE_ARCH_PERFMON (3*32+9) /* Intel Architectural PerfMon */
#define X86_FEATURE_PEBS (3*32+10) /* Precise-Event Based Sampling */
+#define X86_FEATURE_BTS (3*32+11) /* Branch Trace Store */
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
#define X86_FEATURE_XMM3 (4*32+ 0) /* Streaming SIMD Extensions-3 */
@@ -115,5 +116,6 @@
#define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
#define cpu_has_ds boot_cpu_has(X86_FEATURE_DS)
#define cpu_has_pebs boot_cpu_has(X86_FEATURE_PEBS)
+#define cpu_has_bts boot_cpu_has(X86_FEATURE_BTS)
#endif /* __ASM_X8664_CPUFEATURE_H */