perf/x86/intel/pebs: Add PEBS frontend profiling for Skylake

Skylake has a new FRONTEND_LATENCY PEBS event to accurately profile
frontend problems (like ITLB or decoding issues).

The new event is configured through a separate MSR, which selects
a range of sub events.

Define the extra MSR as a extra reg and export support for it
through sysfs.  To avoid duplicating the existing
tables use a new function to add new entries to existing tables.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1435707205-6676-4-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 13 insertions, 1 deletions

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index c1c0a1c14344..54390bc140dd 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -141,6 +141,8 @@
 #define DEBUGCTLMSR_BTS_OFF_USR         (1UL << 10)
 #define DEBUGCTLMSR_FREEZE_LBRS_ON_PMI  (1UL << 11)
 
+#define MSR_PEBS_FRONTEND               0x000003f7
+
 #define MSR_IA32_POWER_CTL              0x000001fc
 
 #define MSR_IA32_MC0_CTL                0x00000400
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 5edf6d868fc1..165be83a7fa4 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -47,6 +47,7 @@ enum extra_reg_type {
         EXTRA_REG_RSP_1 = 1,    /* offcore_response_1 */
         EXTRA_REG_LBR   = 2,    /* lbr_select */
         EXTRA_REG_LDLAT = 3,    /* ld_lat_threshold */
+        EXTRA_REG_FE    = 4,    /* fe_* */
 
         EXTRA_REG_MAX           /* number of entries needed */
 };
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 1d84b41ba932..ef74c9d05f82 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -205,6 +205,7 @@ static struct extra_reg intel_skl_extra_regs[] __read_mostly = {
         INTEL_UEVENT_EXTRA_REG(0x01b7, MSR_OFFCORE_RSP_0, 0x3fffff8fffull, RSP_0),
         INTEL_UEVENT_EXTRA_REG(0x01bb, MSR_OFFCORE_RSP_1, 0x3fffff8fffull, RSP_1),
         INTEL_UEVENT_PEBS_LDLAT_EXTRA_REG(0x01cd),
+        INTEL_UEVENT_EXTRA_REG(0x01c6, MSR_PEBS_FRONTEND, 0x3fff17, FE),
         EVENT_EXTRA_END
 };
 
@@ -2891,6 +2892,8 @@ PMU_FORMAT_ATTR(offcore_rsp, "config1:0-63");
 
 PMU_FORMAT_ATTR(ldlat, "config1:0-15");
 
+PMU_FORMAT_ATTR(frontend, "config1:0-23");
+
 static struct attribute *intel_arch3_formats_attr[] = {
         &format_attr_event.attr,
         &format_attr_umask.attr,
@@ -2907,6 +2910,11 @@ static struct attribute *intel_arch3_formats_attr[] = {
         NULL,
 };
 
+static struct attribute *skl_format_attr[] = {
+        &format_attr_frontend.attr,
+        NULL,
+};
+
 static __initconst const struct x86_pmu core_pmu = {
         .name                   = "core",
         .handle_irq             = x86_pmu_handle_irq,
@@ -3516,7 +3524,8 @@ __init int intel_pmu_init(void)
 
                 x86_pmu.hw_config = hsw_hw_config;
                 x86_pmu.get_event_constraints = hsw_get_event_constraints;
-                x86_pmu.cpu_events = hsw_events_attrs;
+                x86_pmu.format_attrs = merge_attr(intel_arch3_formats_attr,
+                                                  skl_format_attr);
                 WARN_ON(!x86_pmu.format_attrs);
                 x86_pmu.cpu_events = hsw_events_attrs;
                 pr_cont("Skylake events, ");