perf, x86: Clean up IA32_PERF_CAPABILITIES usage

Saner PERF_CAPABILITIES support, which also exposes pebs_trap. Use that
latter to make PEBS's use of LBR conditional since a fault-like pebs
should already report the correct IP.

( As of this writing there is no known hardware that implements
  !pebs_trap )

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
LKML-Reference: <20100304140100.770650663@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 42 insertions, 31 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 5cb4e8dcee4b..7b5430b2efe7 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -154,6 +154,17 @@ struct cpu_hw_events {
 #define for_each_event_constraint(e, c) \
         for ((e) = (c); (e)->cmask; (e)++)
 
+union perf_capabilities {
+        struct {
+                u64     lbr_format    : 6;
+                u64     pebs_trap     : 1;
+                u64     pebs_arch_reg : 1;
+                u64     pebs_format   : 4;
+                u64     smm_freeze    : 1;
+        };
+        u64     capabilities;
+};
+
 /*
  * struct x86_pmu - generic x86 pmu
  */
@@ -195,7 +206,8 @@ struct x86_pmu {
         /*
          * Intel Arch Perfmon v2+
          */
-        u64             intel_ctrl;
+        u64                     intel_ctrl;
+        union perf_capabilities intel_cap;
 
         /*
          * Intel DebugStore bits
@@ -210,7 +222,6 @@ struct x86_pmu {
          */
         unsigned long   lbr_tos, lbr_from, lbr_to; /* MSR base regs       */
         int             lbr_nr;                    /* hardware stack size */
-        int             lbr_format;                /* hardware format     */
 };
 
 static struct x86_pmu x86_pmu __read_mostly;
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 7eb78be3b229..246c07238823 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -835,6 +835,16 @@ static __init int intel_pmu_init(void)
         if (version > 1)
                 x86_pmu.num_events_fixed = max((int)edx.split.num_events_fixed, 3);
 
+        /*
+         * v2 and above have a perf capabilities MSR
+         */
+        if (version > 1) {
+                u64 capabilities;
+
+                rdmsrl(MSR_IA32_PERF_CAPABILITIES, capabilities);
+                x86_pmu.intel_cap.capabilities = capabilities;
+        }
+
         intel_ds_init();
 
         /*
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 50e6ff3281fc..5e4029441b2d 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -342,7 +342,8 @@ static void intel_pmu_pebs_enable(struct perf_event *event)
         val |= 1ULL << hwc->idx;
         wrmsrl(MSR_IA32_PEBS_ENABLE, val);
 
-        intel_pmu_lbr_enable(event);
+        if (x86_pmu.intel_cap.pebs_trap)
+                intel_pmu_lbr_enable(event);
 }
 
 static void intel_pmu_pebs_disable(struct perf_event *event)
@@ -356,7 +357,8 @@ static void intel_pmu_pebs_disable(struct perf_event *event)
 
         hwc->config |= ARCH_PERFMON_EVENTSEL_INT;
 
-        intel_pmu_lbr_disable(event);
+        if (x86_pmu.intel_cap.pebs_trap)
+                intel_pmu_lbr_disable(event);
 }
 
 static void intel_pmu_pebs_enable_all(void)
@@ -395,6 +397,12 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
         unsigned long old_to, to = cpuc->lbr_entries[0].to;
         unsigned long ip = regs->ip;
 
+        /*
+         * We don't need to fixup if the PEBS assist is fault like
+         */
+        if (!x86_pmu.intel_cap.pebs_trap)
+                return 1;
+
         if (!cpuc->lbr_stack.nr || !from || !to)
                 return 0;
 
@@ -589,34 +597,26 @@ static void intel_ds_init(void)
         x86_pmu.bts  = boot_cpu_has(X86_FEATURE_BTS);
         x86_pmu.pebs = boot_cpu_has(X86_FEATURE_PEBS);
         if (x86_pmu.pebs) {
-                int format = 0;
-
-                if (x86_pmu.version > 1) {
-                        u64 capabilities;
-                        /*
-                         * v2+ has a PEBS format field
-                         */
-                        rdmsrl(MSR_IA32_PERF_CAPABILITIES, capabilities);
-                        format = (capabilities >> 8) & 0xf;
-                }
+                char pebs_type = x86_pmu.intel_cap.pebs_trap ?  '+' : '-';
+                int format = x86_pmu.intel_cap.pebs_format;
 
                 switch (format) {
                 case 0:
-                        printk(KERN_CONT "PEBS v0, ");
+                        printk(KERN_CONT "PEBS fmt0%c, ", pebs_type);
                         x86_pmu.pebs_record_size = sizeof(struct pebs_record_core);
                         x86_pmu.drain_pebs = intel_pmu_drain_pebs_core;
                         x86_pmu.pebs_constraints = intel_core_pebs_events;
                         break;
 
                 case 1:
-                        printk(KERN_CONT "PEBS v1, ");
+                        printk(KERN_CONT "PEBS fmt1%c, ", pebs_type);
                         x86_pmu.pebs_record_size = sizeof(struct pebs_record_nhm);
                         x86_pmu.drain_pebs = intel_pmu_drain_pebs_nhm;
                         x86_pmu.pebs_constraints = intel_nehalem_pebs_events;
                         break;
 
                 default:
-                        printk(KERN_CONT "PEBS unknown format: %d, ", format);
+                        printk(KERN_CONT "no PEBS fmt%d%c, ", format, pebs_type);
                         x86_pmu.pebs = 0;
                         break;
                 }
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index ea3e99ed82ce..4f3a124329c4 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -53,7 +53,7 @@ static void intel_pmu_lbr_reset_64(void)
 
 static void intel_pmu_lbr_reset(void)
 {
-        if (x86_pmu.lbr_format == LBR_FORMAT_32)
+        if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
                 intel_pmu_lbr_reset_32();
         else
                 intel_pmu_lbr_reset_64();
@@ -155,6 +155,7 @@ static void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc)
 static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
 {
         unsigned long mask = x86_pmu.lbr_nr - 1;
+        int lbr_format = x86_pmu.intel_cap.lbr_format;
         u64 tos = intel_pmu_lbr_tos();
         int i;
 
@@ -165,7 +166,7 @@ static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
                 rdmsrl(x86_pmu.lbr_from + lbr_idx, from);
                 rdmsrl(x86_pmu.lbr_to   + lbr_idx, to);
 
-                if (x86_pmu.lbr_format == LBR_FORMAT_EIP_FLAGS) {
+                if (lbr_format == LBR_FORMAT_EIP_FLAGS) {
                         flags = !!(from & LBR_FROM_FLAG_MISPRED);
                         from = (u64)((((s64)from) << 1) >> 1);
                 }
@@ -184,23 +185,14 @@ static void intel_pmu_lbr_read(void)
         if (!cpuc->lbr_users)
                 return;
 
-        if (x86_pmu.lbr_format == LBR_FORMAT_32)
+        if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
                 intel_pmu_lbr_read_32(cpuc);
         else
                 intel_pmu_lbr_read_64(cpuc);
 }
 
-static int intel_pmu_lbr_format(void)
-{
-        u64 capabilities;
-
-        rdmsrl(MSR_IA32_PERF_CAPABILITIES, capabilities);
-        return capabilities & 0x1f;
-}
-
 static void intel_pmu_lbr_init_core(void)
 {
-        x86_pmu.lbr_format = intel_pmu_lbr_format();
         x86_pmu.lbr_nr     = 4;
         x86_pmu.lbr_tos    = 0x01c9;
         x86_pmu.lbr_from   = 0x40;
@@ -209,7 +201,6 @@ static void intel_pmu_lbr_init_core(void)
 
 static void intel_pmu_lbr_init_nhm(void)
 {
-        x86_pmu.lbr_format = intel_pmu_lbr_format();
         x86_pmu.lbr_nr     = 16;
         x86_pmu.lbr_tos    = 0x01c9;
         x86_pmu.lbr_from   = 0x680;
@@ -218,7 +209,6 @@ static void intel_pmu_lbr_init_nhm(void)
 
 static void intel_pmu_lbr_init_atom(void)
 {
-        x86_pmu.lbr_format = intel_pmu_lbr_format();
         x86_pmu.lbr_nr     = 8;
         x86_pmu.lbr_tos    = 0x01c9;
         x86_pmu.lbr_from   = 0x40;