sparc64: Initial hw perf counter support.

Only supports one simple counter and only UltraSPARC-IIIi chips.

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 538 insertions, 2 deletions

diff --git a/arch/sparc/include/asm/nmi.h b/arch/sparc/include/asm/nmi.h
index c7d11e435df9..72e6500e7ab0 100644
--- a/arch/sparc/include/asm/nmi.h
+++ b/arch/sparc/include/asm/nmi.h
@@ -7,4 +7,7 @@ extern void nmi_adjust_hz(unsigned int new_hz);
 
 extern atomic_t nmi_active;
 
+extern void start_nmi_watchdog(void *unused);
+extern void stop_nmi_watchdog(void *unused);
+
 #endif /* __NMI_H */
diff --git a/arch/sparc/include/asm/perf_counter.h b/arch/sparc/include/asm/perf_counter.h
index 38d644546435..5d7a8ca0e491 100644
--- a/arch/sparc/include/asm/perf_counter.h
+++ b/arch/sparc/include/asm/perf_counter.h
@@ -5,4 +5,10 @@ extern void set_perf_counter_pending(void);
 
 #define PERF_COUNTER_INDEX_OFFSET       0
 
+#ifdef CONFIG_PERF_COUNTERS
+extern void init_hw_perf_counters(void);
+#else
+static inline void init_hw_perf_counters(void)  { }
+#endif
+
 #endif
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
index b0041756c9f0..f96dc5761f74 100644
--- a/arch/sparc/kernel/Makefile
+++ b/arch/sparc/kernel/Makefile
@@ -103,3 +103,6 @@ obj-$(CONFIG_SUN_LDOMS) += ldc.o vio.o viohs.o ds.o
 obj-$(CONFIG_AUDIT)     += audit.o
 audit--$(CONFIG_AUDIT)  := compat_audit.o
 obj-$(CONFIG_COMPAT)    += $(audit--y)
+
+pc--$(CONFIG_PERF_COUNTERS) := perf_counter.o
+obj-$(CONFIG_SPARC64)   += $(pc--y)
diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index 7de19dd30f40..391a6ed9a184 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -19,6 +19,7 @@
 #include <linux/delay.h>
 #include <linux/smp.h>
 
+#include <asm/perf_counter.h>
 #include <asm/ptrace.h>
 #include <asm/local.h>
 #include <asm/pcr.h>
@@ -156,7 +157,7 @@ static void report_broken_nmi(int cpu, int *prev_nmi_count)
         atomic_dec(&nmi_active);
 }
 
-static void stop_nmi_watchdog(void *unused)
+void stop_nmi_watchdog(void *unused)
 {
         pcr_ops->write(PCR_PIC_PRIV);
         __get_cpu_var(wd_enabled) = 0;
@@ -210,7 +211,7 @@ error:
         return err;
 }
 
-static void start_nmi_watchdog(void *unused)
+void start_nmi_watchdog(void *unused)
 {
         __get_cpu_var(wd_enabled) = 1;
         atomic_inc(&nmi_active);
@@ -263,6 +264,9 @@ int __init nmi_init(void)
                         atomic_set(&nmi_active, -1);
                 }
         }
+        if (!err)
+                init_hw_perf_counters();
+
         return err;
 }
 
diff --git a/arch/sparc/kernel/perf_counter.c b/arch/sparc/kernel/perf_counter.c
new file mode 100644
index 000000000000..f2c781450d08
--- /dev/null
+++ b/arch/sparc/kernel/perf_counter.c
@@ -0,0 +1,520 @@
+/* Performance counter support for sparc64.
+ *
+ * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
+ *
+ * This code is based almost entirely upon the x86 perf counter
+ * code, which is:
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2009 Jaswinder Singh Rajput
+ *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
+ */
+
+#include <linux/perf_counter.h>
+#include <linux/kprobes.h>
+#include <linux/kernel.h>
+#include <linux/kdebug.h>
+#include <linux/mutex.h>
+
+#include <asm/cpudata.h>
+#include <asm/atomic.h>
+#include <asm/nmi.h>
+#include <asm/pcr.h>
+
+/* Sparc64 chips have two performance counters, 32-bits each, with
+ * overflow interrupts generated on transition from 0xffffffff to 0.
+ * The counters are accessed in one go using a 64-bit register.
+ *
+ * Both counters are controlled using a single control register.  The
+ * only way to stop all sampling is to clear all of the context (user,
+ * supervisor, hypervisor) sampling enable bits.  But these bits apply
+ * to both counters, thus the two counters can't be enabled/disabled
+ * individually.
+ *
+ * The control register has two event fields, one for each of the two
+ * counters.  It's thus nearly impossible to have one counter going
+ * while keeping the other one stopped.  Therefore it is possible to
+ * get overflow interrupts for counters not currently "in use" and
+ * that condition must be checked in the overflow interrupt handler.
+ *
+ * So we use a hack, in that we program inactive counters with the
+ * "sw_count0" and "sw_count1" events.  These count how many times
+ * the instruction "sethi %hi(0xfc000), %g0" is executed.  It's an
+ * unusual way to encode a NOP and therefore will not trigger in
+ * normal code.
+ */
+
+#define MAX_HWCOUNTERS                  2
+#define MAX_PERIOD                      ((1UL << 32) - 1)
+
+#define PIC_UPPER_INDEX                 0
+#define PIC_LOWER_INDEX                 1
+
+#define PIC_UPPER_NOP                   0x1c
+#define PIC_LOWER_NOP                   0x14
+
+struct cpu_hw_counters {
+        struct perf_counter     *counters[MAX_HWCOUNTERS];
+        unsigned long           used_mask[BITS_TO_LONGS(MAX_HWCOUNTERS)];
+        unsigned long           active_mask[BITS_TO_LONGS(MAX_HWCOUNTERS)];
+        int enabled;
+};
+DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters) = { .enabled = 1, };
+
+struct perf_event_map {
+        u16     encoding;
+        u8      pic_mask;
+#define PIC_NONE        0x00
+#define PIC_UPPER       0x01
+#define PIC_LOWER       0x02
+};
+
+struct sparc_pmu {
+        const struct perf_event_map     *(*event_map)(int);
+        int                             max_events;
+        int                             upper_shift;
+        int                             lower_shift;
+        int                             event_mask;
+};
+
+static const struct perf_event_map ultra3i_perfmon_event_map[] = {
+        [PERF_COUNT_HW_CPU_CYCLES] = { 0x0000, PIC_UPPER | PIC_LOWER },
+        [PERF_COUNT_HW_INSTRUCTIONS] = { 0x0001, PIC_UPPER | PIC_LOWER },
+        [PERF_COUNT_HW_CACHE_REFERENCES] = { 0x0009, PIC_LOWER },
+        [PERF_COUNT_HW_CACHE_MISSES] = { 0x0009, PIC_UPPER },
+};
+
+static const struct perf_event_map *ultra3i_event_map(int event)
+{
+        return &ultra3i_perfmon_event_map[event];
+}
+
+static const struct sparc_pmu ultra3i_pmu = {
+        .event_map      = ultra3i_event_map,
+        .max_events     = ARRAY_SIZE(ultra3i_perfmon_event_map),
+        .upper_shift    = 11,
+        .lower_shift    = 4,
+        .event_mask     = 0x3f,
+};
+
+static const struct sparc_pmu *sparc_pmu __read_mostly;
+
+static u64 event_encoding(u64 event, int idx)
+{
+        if (idx == PIC_UPPER_INDEX)
+                event <<= sparc_pmu->upper_shift;
+        else
+                event <<= sparc_pmu->lower_shift;
+        return event;
+}
+
+static u64 mask_for_index(int idx)
+{
+        return event_encoding(sparc_pmu->event_mask, idx);
+}
+
+static u64 nop_for_index(int idx)
+{
+        return event_encoding(idx == PIC_UPPER_INDEX ?
+                              PIC_UPPER_NOP : PIC_LOWER_NOP, idx);
+}
+
+static inline void sparc_pmu_enable_counter(struct hw_perf_counter *hwc,
+                                            int idx)
+{
+        u64 val, mask = mask_for_index(idx);
+
+        val = pcr_ops->read();
+        pcr_ops->write((val & ~mask) | hwc->config);
+}
+
+static inline void sparc_pmu_disable_counter(struct hw_perf_counter *hwc,
+                                             int idx)
+{
+        u64 mask = mask_for_index(idx);
+        u64 nop = nop_for_index(idx);
+        u64 val = pcr_ops->read();
+
+        pcr_ops->write((val & ~mask) | nop);
+}
+
+void hw_perf_enable(void)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        u64 val;
+        int i;
+
+        if (cpuc->enabled)
+                return;
+
+        cpuc->enabled = 1;
+        barrier();
+
+        val = pcr_ops->read();
+
+        for (i = 0; i < MAX_HWCOUNTERS; i++) {
+                struct perf_counter *cp = cpuc->counters[i];
+                struct hw_perf_counter *hwc;
+
+                if (!cp)
+                        continue;
+                hwc = &cp->hw;
+                val |= hwc->config_base;
+        }
+
+        pcr_ops->write(val);
+}
+
+void hw_perf_disable(void)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        u64 val;
+
+        if (!cpuc->enabled)
+                return;
+
+        cpuc->enabled = 0;
+
+        val = pcr_ops->read();
+        val &= ~(PCR_UTRACE | PCR_STRACE);
+        pcr_ops->write(val);
+}
+
+static u32 read_pmc(int idx)
+{
+        u64 val;
+
+        read_pic(val);
+        if (idx == PIC_UPPER_INDEX)
+                val >>= 32;
+
+        return val & 0xffffffff;
+}
+
+static void write_pmc(int idx, u64 val)
+{
+        u64 shift, mask, pic;
+
+        shift = 0;
+        if (idx == PIC_UPPER_INDEX)
+                shift = 32;
+
+        mask = ((u64) 0xffffffff) << shift;
+        val <<= shift;
+
+        read_pic(pic);
+        pic &= ~mask;
+        pic |= val;
+        write_pic(pic);
+}
+
+static int sparc_perf_counter_set_period(struct perf_counter *counter,
+                                         struct hw_perf_counter *hwc, int idx)
+{
+        s64 left = atomic64_read(&hwc->period_left);
+        s64 period = hwc->sample_period;
+        int ret = 0;
+
+        if (unlikely(left <= -period)) {
+                left = period;
+                atomic64_set(&hwc->period_left, left);
+                hwc->last_period = period;
+                ret = 1;
+        }
+
+        if (unlikely(left <= 0)) {
+                left += period;
+                atomic64_set(&hwc->period_left, left);
+                hwc->last_period = period;
+                ret = 1;
+        }
+        if (left > MAX_PERIOD)
+                left = MAX_PERIOD;
+
+        atomic64_set(&hwc->prev_count, (u64)-left);
+
+        write_pmc(idx, (u64)(-left) & 0xffffffff);
+
+        perf_counter_update_userpage(counter);
+
+        return ret;
+}
+
+static int sparc_pmu_enable(struct perf_counter *counter)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        struct hw_perf_counter *hwc = &counter->hw;
+        int idx = hwc->idx;
+
+        if (test_and_set_bit(idx, cpuc->used_mask))
+                return -EAGAIN;
+
+        sparc_pmu_disable_counter(hwc, idx);
+
+        cpuc->counters[idx] = counter;
+        set_bit(idx, cpuc->active_mask);
+
+        sparc_perf_counter_set_period(counter, hwc, idx);
+        sparc_pmu_enable_counter(hwc, idx);
+        perf_counter_update_userpage(counter);
+        return 0;
+}
+
+static u64 sparc_perf_counter_update(struct perf_counter *counter,
+                                     struct hw_perf_counter *hwc, int idx)
+{
+        int shift = 64 - 32;
+        u64 prev_raw_count, new_raw_count;
+        s64 delta;
+
+again:
+        prev_raw_count = atomic64_read(&hwc->prev_count);
+        new_raw_count = read_pmc(idx);
+
+        if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
+                             new_raw_count) != prev_raw_count)
+                goto again;
+
+        delta = (new_raw_count << shift) - (prev_raw_count << shift);
+        delta >>= shift;
+
+        atomic64_add(delta, &counter->count);
+        atomic64_sub(delta, &hwc->period_left);
+
+        return new_raw_count;
+}
+
+static void sparc_pmu_disable(struct perf_counter *counter)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        struct hw_perf_counter *hwc = &counter->hw;
+        int idx = hwc->idx;
+
+        clear_bit(idx, cpuc->active_mask);
+        sparc_pmu_disable_counter(hwc, idx);
+
+        barrier();
+
+        sparc_perf_counter_update(counter, hwc, idx);
+        cpuc->counters[idx] = NULL;
+        clear_bit(idx, cpuc->used_mask);
+
+        perf_counter_update_userpage(counter);
+}
+
+static void sparc_pmu_read(struct perf_counter *counter)
+{
+        struct hw_perf_counter *hwc = &counter->hw;
+        sparc_perf_counter_update(counter, hwc, hwc->idx);
+}
+
+static void sparc_pmu_unthrottle(struct perf_counter *counter)
+{
+        struct hw_perf_counter *hwc = &counter->hw;
+        sparc_pmu_enable_counter(hwc, hwc->idx);
+}
+
+static atomic_t active_counters = ATOMIC_INIT(0);
+static DEFINE_MUTEX(pmc_grab_mutex);
+
+void perf_counter_grab_pmc(void)
+{
+        if (atomic_inc_not_zero(&active_counters))
+                return;
+
+        mutex_lock(&pmc_grab_mutex);
+        if (atomic_read(&active_counters) == 0) {
+                if (atomic_read(&nmi_active) > 0) {
+                        on_each_cpu(stop_nmi_watchdog, NULL, 1);
+                        BUG_ON(atomic_read(&nmi_active) != 0);
+                }
+                atomic_inc(&active_counters);
+        }
+        mutex_unlock(&pmc_grab_mutex);
+}
+
+void perf_counter_release_pmc(void)
+{
+        if (atomic_dec_and_mutex_lock(&active_counters, &pmc_grab_mutex)) {
+                if (atomic_read(&nmi_active) == 0)
+                        on_each_cpu(start_nmi_watchdog, NULL, 1);
+                mutex_unlock(&pmc_grab_mutex);
+        }
+}
+
+static void hw_perf_counter_destroy(struct perf_counter *counter)
+{
+        perf_counter_release_pmc();
+}
+
+static int __hw_perf_counter_init(struct perf_counter *counter)
+{
+        struct perf_counter_attr *attr = &counter->attr;
+        struct hw_perf_counter *hwc = &counter->hw;
+        const struct perf_event_map *pmap;
+        u64 enc;
+
+        if (atomic_read(&nmi_active) < 0)
+                return -ENODEV;
+
+        if (attr->type != PERF_TYPE_HARDWARE)
+                return -EOPNOTSUPP;
+
+        if (attr->config >= sparc_pmu->max_events)
+                return -EINVAL;
+
+        perf_counter_grab_pmc();
+        counter->destroy = hw_perf_counter_destroy;
+
+        /* We save the enable bits in the config_base.  So to
+         * turn off sampling just write 'config', and to enable
+         * things write 'config | config_base'.
+         */
+        hwc->config_base = 0;
+        if (!attr->exclude_user)
+                hwc->config_base |= PCR_UTRACE;
+        if (!attr->exclude_kernel)
+                hwc->config_base |= PCR_STRACE;
+
+        if (!hwc->sample_period) {
+                hwc->sample_period = MAX_PERIOD;
+                hwc->last_period = hwc->sample_period;
+                atomic64_set(&hwc->period_left, hwc->sample_period);
+        }
+
+        pmap = sparc_pmu->event_map(attr->config);
+
+        enc = pmap->encoding;
+        if (pmap->pic_mask & PIC_UPPER) {
+                hwc->idx = PIC_UPPER_INDEX;
+                enc <<= sparc_pmu->upper_shift;
+        } else {
+                hwc->idx = PIC_LOWER_INDEX;
+                enc <<= sparc_pmu->lower_shift;
+        }
+
+        hwc->config |= enc;
+        return 0;
+}
+
+static const struct pmu pmu = {
+        .enable         = sparc_pmu_enable,
+        .disable        = sparc_pmu_disable,
+        .read           = sparc_pmu_read,
+        .unthrottle     = sparc_pmu_unthrottle,
+};
+
+const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
+{
+        int err = __hw_perf_counter_init(counter);
+
+        if (err)
+                return ERR_PTR(err);
+        return &pmu;
+}
+
+void perf_counter_print_debug(void)
+{
+        unsigned long flags;
+        u64 pcr, pic;
+        int cpu;
+
+        if (!sparc_pmu)
+                return;
+
+        local_irq_save(flags);
+
+        cpu = smp_processor_id();
+
+        pcr = pcr_ops->read();
+        read_pic(pic);
+
+        pr_info("\n");
+        pr_info("CPU#%d: PCR[%016llx] PIC[%016llx]\n",
+                cpu, pcr, pic);
+
+        local_irq_restore(flags);
+}
+
+static int __kprobes perf_counter_nmi_handler(struct notifier_block *self,
+                                              unsigned long cmd, void *__args)
+{
+        struct die_args *args = __args;
+        struct perf_sample_data data;
+        struct cpu_hw_counters *cpuc;
+        struct pt_regs *regs;
+        int idx;
+
+        if (!atomic_read(&active_counters))
+                return NOTIFY_DONE;
+
+        switch (cmd) {
+        case DIE_NMI:
+                break;
+
+        default:
+                return NOTIFY_DONE;
+        }
+
+        regs = args->regs;
+
+        data.regs = regs;
+        data.addr = 0;
+
+        cpuc = &__get_cpu_var(cpu_hw_counters);
+        for (idx = 0; idx < MAX_HWCOUNTERS; idx++) {
+                struct perf_counter *counter = cpuc->counters[idx];
+                struct hw_perf_counter *hwc;
+                u64 val;
+
+                if (!test_bit(idx, cpuc->active_mask))
+                        continue;
+                hwc = &counter->hw;
+                val = sparc_perf_counter_update(counter, hwc, idx);
+                if (val & (1ULL << 31))
+                        continue;
+
+                data.period = counter->hw.last_period;
+                if (!sparc_perf_counter_set_period(counter, hwc, idx))
+                        continue;
+
+                if (perf_counter_overflow(counter, 1, &data))
+                        sparc_pmu_disable_counter(hwc, idx);
+        }
+
+        return NOTIFY_STOP;
+}
+
+static __read_mostly struct notifier_block perf_counter_nmi_notifier = {
+        .notifier_call          = perf_counter_nmi_handler,
+};
+
+static bool __init supported_pmu(void)
+{
+        if (!strcmp(sparc_pmu_type, "ultra3i")) {
+                sparc_pmu = &ultra3i_pmu;
+                return true;
+        }
+        return false;
+}
+
+void __init init_hw_perf_counters(void)
+{
+        pr_info("Performance counters: ");
+
+        if (!supported_pmu()) {
+                pr_cont("No support for PMU type '%s'\n", sparc_pmu_type);
+                return;
+        }
+
+        pr_cont("Supported PMU type is '%s'\n", sparc_pmu_type);
+
+        /* All sparc64 PMUs currently have 2 counters.  But this simple
+         * driver only supports one active counter at a time.
+         */
+        perf_max_counters = 1;
+
+        register_die_notifier(&perf_counter_nmi_notifier);
+}