perf_counter: Add P6 PMU support

Add basic P6 PMU support. The P6 uses the EVNTSEL0 EN bit to
enable/disable both its counters. We use this for the
global enable/disable, and clear all config bits (except EN)
to disable individual counters.

Actual ia32 hardware doesn't support lfence, so use a locked
op without side-effect to implement a full barrier.

perf stat and perf record seem to function correctly.

[a.p.zijlstra@chello.nl: cleanups and complete the enable/disable code]

Signed-off-by: Vince Weaver <vince@deater.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <Pine.LNX.4.64.0907081718450.2715@pianoman.cluster.toy>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 213 insertions, 14 deletions

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 36c3dc7b8991..1910f39ff19a 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -66,6 +66,44 @@ static DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters) = {
 };
 
 /*
+ * Not sure about some of these
+ */
+static const u64 p6_perfmon_event_map[] =
+{
+  [PERF_COUNT_HW_CPU_CYCLES]            = 0x0079,
+  [PERF_COUNT_HW_INSTRUCTIONS]          = 0x00c0,
+  [PERF_COUNT_HW_CACHE_REFERENCES]      = 0x0000,
+  [PERF_COUNT_HW_CACHE_MISSES]          = 0x0000,
+  [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]   = 0x00c4,
+  [PERF_COUNT_HW_BRANCH_MISSES]         = 0x00c5,
+  [PERF_COUNT_HW_BUS_CYCLES]            = 0x0062,
+};
+
+static u64 p6_pmu_event_map(int event)
+{
+        return p6_perfmon_event_map[event];
+}
+
+static u64 p6_pmu_raw_event(u64 event)
+{
+#define P6_EVNTSEL_EVENT_MASK           0x000000FFULL
+#define P6_EVNTSEL_UNIT_MASK            0x0000FF00ULL
+#define P6_EVNTSEL_EDGE_MASK            0x00040000ULL
+#define P6_EVNTSEL_INV_MASK             0x00800000ULL
+#define P6_EVNTSEL_COUNTER_MASK         0xFF000000ULL
+
+#define P6_EVNTSEL_MASK                 \
+        (P6_EVNTSEL_EVENT_MASK |        \
+         P6_EVNTSEL_UNIT_MASK  |        \
+         P6_EVNTSEL_EDGE_MASK  |        \
+         P6_EVNTSEL_INV_MASK   |        \
+         P6_EVNTSEL_COUNTER_MASK)
+
+        return event & P6_EVNTSEL_MASK;
+}
+
+
+/*
  * Intel PerfMon v3. Used on Core2 and later.
  */
 static const u64 intel_perfmon_event_map[] =
@@ -726,6 +764,23 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
         return 0;
 }
 
+static void p6_pmu_disable_all(void)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        unsigned long val;
+
+        if (!cpuc->enabled)
+                return;
+
+        cpuc->enabled = 0;
+        barrier();
+
+        /* p6 only has one enable register */
+        rdmsrl(MSR_P6_EVNTSEL0, val);
+        val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE;
+        wrmsrl(MSR_P6_EVNTSEL0, val);
+}
+
 static void intel_pmu_disable_all(void)
 {
         wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0);
@@ -767,6 +822,23 @@ void hw_perf_disable(void)
         return x86_pmu.disable_all();
 }
 
+static void p6_pmu_enable_all(void)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        unsigned long val;
+
+        if (cpuc->enabled)
+                return;
+
+        cpuc->enabled = 1;
+        barrier();
+
+        /* p6 only has one enable register */
+        rdmsrl(MSR_P6_EVNTSEL0, val);
+        val |= ARCH_PERFMON_EVENTSEL0_ENABLE;
+        wrmsrl(MSR_P6_EVNTSEL0, val);
+}
+
 static void intel_pmu_enable_all(void)
 {
         wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl);
@@ -819,16 +891,13 @@ static inline void intel_pmu_ack_status(u64 ack)
 
 static inline void x86_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
 {
-        int err;
-        err = checking_wrmsrl(hwc->config_base + idx,
+        (void)checking_wrmsrl(hwc->config_base + idx,
                               hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE);
 }
 
 static inline void x86_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
 {
-        int err;
-        err = checking_wrmsrl(hwc->config_base + idx,
-                              hwc->config);
+        (void)checking_wrmsrl(hwc->config_base + idx, hwc->config);
 }
 
 static inline void
@@ -836,13 +905,24 @@ intel_pmu_disable_fixed(struct hw_perf_counter *hwc, int __idx)
 {
         int idx = __idx - X86_PMC_IDX_FIXED;
         u64 ctrl_val, mask;
-        int err;
 
         mask = 0xfULL << (idx * 4);
 
         rdmsrl(hwc->config_base, ctrl_val);
         ctrl_val &= ~mask;
-        err = checking_wrmsrl(hwc->config_base, ctrl_val);
+        (void)checking_wrmsrl(hwc->config_base, ctrl_val);
+}
+
+static inline void
+p6_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        unsigned long val = ARCH_PERFMON_EVENTSEL0_ENABLE;
+
+        if (!cpuc->enabled)
+                val = 0;
+
+        (void)checking_wrmsrl(hwc->config_base + idx, val);
 }
 
 static inline void
@@ -943,6 +1023,17 @@ intel_pmu_enable_fixed(struct hw_perf_counter *hwc, int __idx)
         err = checking_wrmsrl(hwc->config_base, ctrl_val);
 }
 
+static void p6_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+
+        if (cpuc->enabled)
+                x86_pmu_enable_counter(hwc, idx);
+        else
+                x86_pmu_disable_counter(hwc, idx);
+}
+
+
 static void intel_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
 {
         if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
@@ -1176,6 +1267,49 @@ static void intel_pmu_reset(void)
         local_irq_restore(flags);
 }
 
+static int p6_pmu_handle_irq(struct pt_regs *regs)
+{
+        struct perf_sample_data data;
+        struct cpu_hw_counters *cpuc;
+        struct perf_counter *counter;
+        struct hw_perf_counter *hwc;
+        int idx, handled = 0;
+        u64 val;
+
+        data.regs = regs;
+        data.addr = 0;
+
+        cpuc = &__get_cpu_var(cpu_hw_counters);
+
+        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+                if (!test_bit(idx, cpuc->active_mask))
+                        continue;
+
+                counter = cpuc->counters[idx];
+                hwc = &counter->hw;
+
+                val = x86_perf_counter_update(counter, hwc, idx);
+                if (val & (1ULL << (x86_pmu.counter_bits - 1)))
+                        continue;
+
+                /*
+                 * counter overflow
+                 */
+                handled         = 1;
+                data.period     = counter->hw.last_period;
+
+                if (!x86_perf_counter_set_period(counter, hwc, idx))
+                        continue;
+
+                if (perf_counter_overflow(counter, 1, &data))
+                        p6_pmu_disable_counter(hwc, idx);
+        }
+
+        if (handled)
+                inc_irq_stat(apic_perf_irqs);
+
+        return handled;
+}
 
 /*
  * This handler is triggered by the local APIC, so the APIC IRQ handling
@@ -1185,14 +1319,13 @@ static int intel_pmu_handle_irq(struct pt_regs *regs)
 {
         struct perf_sample_data data;
         struct cpu_hw_counters *cpuc;
-        int bit, cpu, loops;
+        int bit, loops;
         u64 ack, status;
 
         data.regs = regs;
         data.addr = 0;
 
-        cpu = smp_processor_id();
-        cpuc = &per_cpu(cpu_hw_counters, cpu);
+        cpuc = &__get_cpu_var(cpu_hw_counters);
 
         perf_disable();
         status = intel_pmu_get_status();
@@ -1249,14 +1382,13 @@ static int amd_pmu_handle_irq(struct pt_regs *regs)
         struct cpu_hw_counters *cpuc;
         struct perf_counter *counter;
         struct hw_perf_counter *hwc;
-        int cpu, idx, handled = 0;
+        int idx, handled = 0;
         u64 val;
 
         data.regs = regs;
         data.addr = 0;
 
-        cpu = smp_processor_id();
-        cpuc = &per_cpu(cpu_hw_counters, cpu);
+        cpuc = &__get_cpu_var(cpu_hw_counters);
 
         for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                 if (!test_bit(idx, cpuc->active_mask))
@@ -1353,6 +1485,32 @@ static __read_mostly struct notifier_block perf_counter_nmi_notifier = {
         .priority               = 1
 };
 
+static struct x86_pmu p6_pmu = {
+        .name                   = "p6",
+        .handle_irq             = p6_pmu_handle_irq,
+        .disable_all            = p6_pmu_disable_all,
+        .enable_all             = p6_pmu_enable_all,
+        .enable                 = p6_pmu_enable_counter,
+        .disable                = p6_pmu_disable_counter,
+        .eventsel               = MSR_P6_EVNTSEL0,
+        .perfctr                = MSR_P6_PERFCTR0,
+        .event_map              = p6_pmu_event_map,
+        .raw_event              = p6_pmu_raw_event,
+        .max_events             = ARRAY_SIZE(p6_perfmon_event_map),
+        .max_period             = (1ULL << 31) - 1,
+        .version                = 0,
+        .num_counters           = 2,
+        /*
+         * Counters have 40 bits implemented. However they are designed such
+         * that bits [32-39] are sign extensions of bit 31. As such the
+         * effective width of a counter for P6-like PMU is 32 bits only.
+         *
+         * See IA-32 Intel Architecture Software developer manual Vol 3B
+         */
+        .counter_bits           = 32,
+        .counter_mask           = (1ULL << 32) - 1,
+};
+
 static struct x86_pmu intel_pmu = {
         .name                   = "Intel",
         .handle_irq             = intel_pmu_handle_irq,
@@ -1392,6 +1550,41 @@ static struct x86_pmu amd_pmu = {
         .max_period             = (1ULL << 47) - 1,
 };
 
+static int p6_pmu_init(void)
+{
+        int high, low;
+
+        switch (boot_cpu_data.x86_model) {
+        case 1:
+        case 3:  /* Pentium Pro */
+        case 5:
+        case 6:  /* Pentium II */
+        case 7:
+        case 8:
+        case 11: /* Pentium III */
+                break;
+        case 9:
+        case 13:
+                /* for Pentium M, we need to check if PMU exist */
+                rdmsr(MSR_IA32_MISC_ENABLE, low, high);
+                if (low & MSR_IA32_MISC_ENABLE_EMON)
+                        break;
+        default:
+                pr_cont("unsupported p6 CPU model %d ",
+                        boot_cpu_data.x86_model);
+                return -ENODEV;
+        }
+
+        if (!cpu_has_apic) {
+                pr_info("no Local APIC, try rebooting with lapic");
+                return -ENODEV;
+        }
+
+        x86_pmu                         = p6_pmu;
+
+        return 0;
+}
+
 static int intel_pmu_init(void)
 {
         union cpuid10_edx edx;
@@ -1400,8 +1593,14 @@ static int intel_pmu_init(void)
         unsigned int ebx;
         int version;
 
-        if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
+        if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
+                /* check for P6 processor family */
+           if (boot_cpu_data.x86 == 6) {
+                return p6_pmu_init();
+           } else {
                 return -ENODEV;
+           }
+        }
 
         /*
          * Check whether the Architectural PerfMon supports