x86, perfcounters: add support for fixed-function pmcs

Impact: extend performance counter support on x86 Intel CPUs

Modern Intel CPUs have 3 "fixed-function" performance counters, which
count these hardware events:

    Instr_Retired.Any
    CPU_CLK_Unhalted.Core
    CPU_CLK_Unhalted.Ref

Add support for them to the performance counters subsystem.

Their use is transparent to user-space: the counter scheduler is
extended to automatically recognize the cases where a fixed-function
PMC can be utilized instead of a generic PMC. In such cases the
generic PMC is kept available for more counters.

The above fixed-function events map to these generic counter hw events:

        PERF_COUNT_INSTRUCTIONS
        PERF_COUNT_CPU_CYCLES
        PERF_COUNT_BUS_CYCLES

(The 'bus' cycles are in reality often CPU-ish cycles, just with a fixed
 frequency.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/include/asm/perf_counter.h b/arch/x86/include/asm/perf_counter.h
index 13745deb16c8..2e08ed736647 100644
--- a/arch/x86/include/asm/perf_counter.h
+++ b/arch/x86/include/asm/perf_counter.h
@@ -23,6 +23,11 @@
 #define ARCH_PERFMON_EVENTSEL_OS                          (1 << 17)
 #define ARCH_PERFMON_EVENTSEL_USR                         (1 << 16)
 
+/*
+ * Includes eventsel and unit mask as well:
+ */
+#define ARCH_PERFMON_EVENT_MASK                             0xffff
+
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL                 0x3c
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK         (0x00 << 8)
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX                  0
@@ -69,12 +74,15 @@ union cpuid10_edx {
 
 /* Instr_Retired.Any: */
 #define MSR_ARCH_PERFMON_FIXED_CTR0                     0x309
+#define X86_PMC_IDX_FIXED_INSTRUCTIONS                  (X86_PMC_IDX_FIXED + 0)
 
 /* CPU_CLK_Unhalted.Core: */
 #define MSR_ARCH_PERFMON_FIXED_CTR1                     0x30a
+#define X86_PMC_IDX_FIXED_CPU_CYCLES                    (X86_PMC_IDX_FIXED + 1)
 
 /* CPU_CLK_Unhalted.Ref: */
 #define MSR_ARCH_PERFMON_FIXED_CTR2                     0x30b
+#define X86_PMC_IDX_FIXED_BUS_CYCLES                    (X86_PMC_IDX_FIXED + 2)
 
 #ifdef CONFIG_PERF_COUNTERS
 extern void init_hw_perf_counters(void);