linux-kernel - [PATCH] x86-64 add Intel PEBS and BTS cpufeature bits and detection

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Message-ID: <20061115213438.GD17238@frankl.hpl.hp.com>
Date:	Wed, 15 Nov 2006 13:34:38 -0800
From:	Stephane Eranian <eranian@....hp.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...l.org, ak@...e.de, Stephane Eranian <eranian@....hp.com>
Subject: [PATCH] x86-64 add Intel PEBS and BTS cpufeature bits and detection

Hello,

Here is a small patch that adds two cpufeature bits to represent
Intel's Precise-Event-Based Sampling (PEBS) and Branch Trace Store
(BTS) features. Those features can be found on Intel P4 and Core 2 
processors among others and can be used by perfmon. This patch is
for x86-64.

changelog:
	- add CPU_FEATURE_PEBS and CPU_FEATURE_BTS
	- add feature detection code

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

diff --exclude=.git -urNp linux-2.6.orig/include/asm-x86_64/cpufeature.h linux-2.6.base/include/asm-x86_64/cpufeature.h
--- linux-2.6.orig/include/asm-x86_64/cpufeature.h	2006-10-17 05:33:56.000000000 -0700
+++ linux-2.6.base/include/asm-x86_64/cpufeature.h	2006-11-15 13:08:25.000000000 -0800
@@ -68,6 +68,8 @@
 #define X86_FEATURE_FXSAVE_LEAK (3*32+7)  /* FIP/FOP/FDP leaks through FXSAVE */
 #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 */
@@ -112,5 +114,8 @@
 #define cpu_has_cyrix_arr      0
 #define cpu_has_centaur_mcr    0
 #define cpu_has_clflush	       boot_cpu_has(X86_FEATURE_CLFLSH)
+#define cpu_has_ds 	       boot_cpu_has(X86_FEATURE_DTES)
+#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 */
diff --exclude=.git -urNp linux-2.6.orig/arch/x86_64/kernel/setup.c linux-2.6.base/arch/x86_64/kernel/setup.c
--- linux-2.6.orig/arch/x86_64/kernel/setup.c	2006-10-17 05:33:35.000000000 -0700
+++ linux-2.6.base/arch/x86_64/kernel/setup.c	2006-11-15 08:21:12.000000000 -0800
@@ -835,6 +835,15 @@ static void __cpuinit init_intel(struct 
 			set_bit(X86_FEATURE_ARCH_PERFMON, &c->x86_capability);
 	}
 
+	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);
+	}
+
 	n = c->extended_cpuid_level;
 	if (n >= 0x80000008) {
 		unsigned eax = cpuid_eax(0x80000008);
-
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