[PATCH] x86-64 add Intel BTS cpufeature bit and detection (take 2)

Stephane Eranian
2006-11-16T14:21:14Z

Andi,

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.

The patch is relative to 2.6.19-rc5-git7 + x86_64-2.6.19-rc5-git7-061116-2

changelog:
- add CPU_FEATURE_BTS
- add Branch Trace Store detection

signed-off-by: stephane eranian <eranian@hpl.hp.com>

diff --exclude=.git -urNp linux-2.6.19-rc5-git7-ak.orig/arch/x86_64/kernel/setup.c linux-2.6.19-rc5-git7-ak/arch/x86_64/kernel/setup.c
--- linux-2.6.19-rc5-git7-ak.orig/arch/x86_64/kernel/setup.c 2006-11-16 05:15:39.000000000 -0800
+++ linux-2.6.19-rc5-git7-ak/arch/x86_64/kernel/setup.c 2006-11-16 05:46:51.000000000 -0800
@@ -838,6 +838,8 @@ static void __cpuinit init_intel(struct
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 --exclude=.git -urNp linux-2.6.19-rc5-git7-ak.orig/include/asm-x86_64/cpufeature.h linux-2.6.19-rc5-git7-ak/include/asm-x86_64/cpufeature.h
--- linux-2.6.19-rc5-git7-ak.orig/include/asm-x86_64/cpufeature.h 2006-11-16 05:15:39.000000000 -0800
+++ linux-2.6.19-rc5-git7-ak/include/asm-x86_64/cpufeature.h 2006-11-16 05:47:52.000000000 -0800
@@ -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 */