sparc64: Fully support both performance counters.

Add the rest of the conflict detection and resolution logic necessary
to support more than one counter at a time on sparc64.

The structure and implementation closely mimicks that of powerpc.

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

1 files changed, 353 insertions, 154 deletions

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 2386ac6ec956..e856456ec02f 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -55,16 +55,49 @@
 
 #define PIC_UPPER_INDEX                 0
 #define PIC_LOWER_INDEX                 1
+#define PIC_NO_INDEX                    -1
 
 struct cpu_hw_events {
-        struct perf_event       *events[MAX_HWEVENTS];
-        unsigned long           used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
-        unsigned long           active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
+        /* Number of events currently scheduled onto this cpu.
+         * This tells how many entries in the arrays below
+         * are valid.
+         */
+        int                     n_events;
+
+        /* Number of new events added since the last hw_perf_disable().
+         * This works because the perf event layer always adds new
+         * events inside of a perf_{disable,enable}() sequence.
+         */
+        int                     n_added;
+
+        /* Array of events current scheduled on this cpu.  */
+        struct perf_event       *event[MAX_HWEVENTS];
+
+        /* Array of encoded longs, specifying the %pcr register
+         * encoding and the mask of PIC counters this even can
+         * be scheduled on.  See perf_event_encode() et al.
+         */
+        unsigned long           events[MAX_HWEVENTS];
+
+        /* The current counter index assigned to an event.  When the
+         * event hasn't been programmed into the cpu yet, this will
+         * hold PIC_NO_INDEX.  The event->hw.idx value tells us where
+         * we ought to schedule the event.
+         */
+        int                     current_idx[MAX_HWEVENTS];
+
+        /* Software copy of %pcr register on this cpu.  */
         u64                     pcr;
+
+        /* Enabled/disable state.  */
         int                     enabled;
 };
 DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = { .enabled = 1, };
 
+/* An event map describes the characteristics of a performance
+ * counter event.  In particular it gives the encoding as well as
+ * a mask telling which counters the event can be measured on.
+ */
 struct perf_event_map {
         u16     encoding;
         u8      pic_mask;
@@ -73,15 +106,20 @@ struct perf_event_map {
 #define PIC_LOWER       0x02
 };
 
+/* Encode a perf_event_map entry into a long.  */
 static unsigned long perf_event_encode(const struct perf_event_map *pmap)
 {
         return ((unsigned long) pmap->encoding << 16) | pmap->pic_mask;
 }
 
-static void perf_event_decode(unsigned long val, u16 *enc, u8 *msk)
+static u8 perf_event_get_msk(unsigned long val)
+{
+        return val & 0xff;
+}
+
+static u64 perf_event_get_enc(unsigned long val)
 {
-        *msk = val & 0xff;
-        *enc = val >> 16;
+        return val >> 16;
 }
 
 #define C(x) PERF_COUNT_HW_CACHE_##x
@@ -495,53 +533,6 @@ static inline void sparc_pmu_disable_event(struct cpu_hw_events *cpuc, struct hw
         pcr_ops->write(cpuc->pcr);
 }
 
-void hw_perf_enable(void)
-{
-        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
-        u64 val;
-        int i;
-
-        if (cpuc->enabled)
-                return;
-
-        cpuc->enabled = 1;
-        barrier();
-
-        val = cpuc->pcr;
-
-        for (i = 0; i < MAX_HWEVENTS; i++) {
-                struct perf_event *cp = cpuc->events[i];
-                struct hw_perf_event *hwc;
-
-                if (!cp)
-                        continue;
-                hwc = &cp->hw;
-                val |= hwc->config_base;
-        }
-
-        cpuc->pcr = val;
-
-        pcr_ops->write(cpuc->pcr);
-}
-
-void hw_perf_disable(void)
-{
-        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
-        u64 val;
-
-        if (!cpuc->enabled)
-                return;
-
-        cpuc->enabled = 0;
-
-        val = cpuc->pcr;
-        val &= ~(PCR_UTRACE | PCR_STRACE |
-                 sparc_pmu->hv_bit | sparc_pmu->irq_bit);
-        cpuc->pcr = val;
-
-        pcr_ops->write(cpuc->pcr);
-}
-
 static u32 read_pmc(int idx)
 {
         u64 val;
@@ -570,6 +561,30 @@ static void write_pmc(int idx, u64 val)
         write_pic(pic);
 }
 
+static u64 sparc_perf_event_update(struct perf_event *event,
+                                   struct hw_perf_event *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, &event->count);
+        atomic64_sub(delta, &hwc->period_left);
+
+        return new_raw_count;
+}
+
 static int sparc_perf_event_set_period(struct perf_event *event,
                                        struct hw_perf_event *hwc, int idx)
 {
@@ -602,81 +617,166 @@ static int sparc_perf_event_set_period(struct perf_event *event,
         return ret;
 }
 
-static int sparc_pmu_enable(struct perf_event *event)
+/* If performance event entries have been added, move existing
+ * events around (if necessary) and then assign new entries to
+ * counters.
+ */
+static u64 maybe_change_configuration(struct cpu_hw_events *cpuc, u64 pcr)
 {
-        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
-        struct hw_perf_event *hwc = &event->hw;
-        int idx = hwc->idx;
+        int i;
 
-        if (test_and_set_bit(idx, cpuc->used_mask))
-                return -EAGAIN;
+        if (!cpuc->n_added)
+                goto out;
 
-        sparc_pmu_disable_event(cpuc, hwc, idx);
+        /* Read in the counters which are moving.  */
+        for (i = 0; i < cpuc->n_events; i++) {
+                struct perf_event *cp = cpuc->event[i];
 
-        cpuc->events[idx] = event;
-        set_bit(idx, cpuc->active_mask);
+                if (cpuc->current_idx[i] != PIC_NO_INDEX &&
+                    cpuc->current_idx[i] != cp->hw.idx) {
+                        sparc_perf_event_update(cp, &cp->hw,
+                                                cpuc->current_idx[i]);
+                        cpuc->current_idx[i] = PIC_NO_INDEX;
+                }
+        }
 
-        sparc_perf_event_set_period(event, hwc, idx);
-        sparc_pmu_enable_event(cpuc, hwc, idx);
-        perf_event_update_userpage(event);
-        return 0;
+        /* Assign to counters all unassigned events.  */
+        for (i = 0; i < cpuc->n_events; i++) {
+                struct perf_event *cp = cpuc->event[i];
+                struct hw_perf_event *hwc = &cp->hw;
+                int idx = hwc->idx;
+                u64 enc;
+
+                if (cpuc->current_idx[i] != PIC_NO_INDEX)
+                        continue;
+
+                sparc_perf_event_set_period(cp, hwc, idx);
+                cpuc->current_idx[i] = idx;
+
+                enc = perf_event_get_enc(cpuc->events[i]);
+                pcr |= event_encoding(enc, idx);
+        }
+out:
+        return pcr;
 }
 
-static u64 sparc_perf_event_update(struct perf_event *event,
-                                   struct hw_perf_event *hwc, int idx)
+void hw_perf_enable(void)
 {
-        int shift = 64 - 32;
-        u64 prev_raw_count, new_raw_count;
-        s64 delta;
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        u64 pcr;
 
-again:
-        prev_raw_count = atomic64_read(&hwc->prev_count);
-        new_raw_count = read_pmc(idx);
+        if (cpuc->enabled)
+                return;
 
-        if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
-                             new_raw_count) != prev_raw_count)
-                goto again;
+        cpuc->enabled = 1;
+        barrier();
 
-        delta = (new_raw_count << shift) - (prev_raw_count << shift);
-        delta >>= shift;
+        pcr = cpuc->pcr;
+        if (!cpuc->n_events) {
+                pcr = 0;
+        } else {
+                pcr = maybe_change_configuration(cpuc, pcr);
 
-        atomic64_add(delta, &event->count);
-        atomic64_sub(delta, &hwc->period_left);
+                /* We require that all of the events have the same
+                 * configuration, so just fetch the settings from the
+                 * first entry.
+                 */
+                cpuc->pcr = pcr | cpuc->event[0]->hw.config_base;
+        }
 
-        return new_raw_count;
+        pcr_ops->write(cpuc->pcr);
+}
+
+void hw_perf_disable(void)
+{
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        u64 val;
+
+        if (!cpuc->enabled)
+                return;
+
+        cpuc->enabled = 0;
+        cpuc->n_added = 0;
+
+        val = cpuc->pcr;
+        val &= ~(PCR_UTRACE | PCR_STRACE |
+                 sparc_pmu->hv_bit | sparc_pmu->irq_bit);
+        cpuc->pcr = val;
+
+        pcr_ops->write(cpuc->pcr);
 }
 
 static void sparc_pmu_disable(struct perf_event *event)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
         struct hw_perf_event *hwc = &event->hw;
-        int idx = hwc->idx;
+        unsigned long flags;
+        int i;
 
-        clear_bit(idx, cpuc->active_mask);
-        sparc_pmu_disable_event(cpuc, hwc, idx);
+        local_irq_save(flags);
+        perf_disable();
+
+        for (i = 0; i < cpuc->n_events; i++) {
+                if (event == cpuc->event[i]) {
+                        int idx = cpuc->current_idx[i];
+
+                        /* Shift remaining entries down into
+                         * the existing slot.
+                         */
+                        while (++i < cpuc->n_events) {
+                                cpuc->event[i - 1] = cpuc->event[i];
+                                cpuc->events[i - 1] = cpuc->events[i];
+                                cpuc->current_idx[i - 1] =
+                                        cpuc->current_idx[i];
+                        }
+
+                        /* Absorb the final count and turn off the
+                         * event.
+                         */
+                        sparc_pmu_disable_event(cpuc, hwc, idx);
+                        barrier();
+                        sparc_perf_event_update(event, hwc, idx);
 
-        barrier();
+                        perf_event_update_userpage(event);
 
-        sparc_perf_event_update(event, hwc, idx);
-        cpuc->events[idx] = NULL;
-        clear_bit(idx, cpuc->used_mask);
+                        cpuc->n_events--;
+                        break;
+                }
+        }
 
-        perf_event_update_userpage(event);
+        perf_enable();
+        local_irq_restore(flags);
+}
+
+static int active_event_index(struct cpu_hw_events *cpuc,
+                              struct perf_event *event)
+{
+        int i;
+
+        for (i = 0; i < cpuc->n_events; i++) {
+                if (cpuc->event[i] == event)
+                        break;
+        }
+        BUG_ON(i == cpuc->n_events);
+        return cpuc->current_idx[i];
 }
 
 static void sparc_pmu_read(struct perf_event *event)
 {
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        int idx = active_event_index(cpuc, event);
         struct hw_perf_event *hwc = &event->hw;
 
-        sparc_perf_event_update(event, hwc, hwc->idx);
+        sparc_perf_event_update(event, hwc, idx);
 }
 
 static void sparc_pmu_unthrottle(struct perf_event *event)
 {
         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        int idx = active_event_index(cpuc, event);
         struct hw_perf_event *hwc = &event->hw;
 
-        sparc_pmu_enable_event(cpuc, hwc, hwc->idx);
+        sparc_pmu_enable_event(cpuc, hwc, idx);
 }
 
 static atomic_t active_events = ATOMIC_INIT(0);
@@ -754,43 +854,75 @@ static void hw_perf_event_destroy(struct perf_event *event)
 /* Make sure all events can be scheduled into the hardware at
  * the same time.  This is simplified by the fact that we only
  * need to support 2 simultaneous HW events.
+ *
+ * As a side effect, the evts[]->hw.idx values will be assigned
+ * on success.  These are pending indexes.  When the events are
+ * actually programmed into the chip, these values will propagate
+ * to the per-cpu cpuc->current_idx[] slots, see the code in
+ * maybe_change_configuration() for details.
  */
-static int sparc_check_constraints(unsigned long *events, int n_ev)
+static int sparc_check_constraints(struct perf_event **evts,
+                                   unsigned long *events, int n_ev)
 {
-        if (n_ev <= perf_max_events) {
-                u8 msk1, msk2;
-                u16 dummy;
-
-                if (n_ev == 1)
-                        return 0;
-                BUG_ON(n_ev != 2);
-                perf_event_decode(events[0], &dummy, &msk1);
-                perf_event_decode(events[1], &dummy, &msk2);
-
-                /* If both events can go on any counter, OK.  */
-                if (msk1 == (PIC_UPPER | PIC_LOWER) &&
-                    msk2 == (PIC_UPPER | PIC_LOWER))
-                        return 0;
-
-                /* If one event is limited to a specific counter,
-                 * and the other can go on both, OK.
-                 */
-                if ((msk1 == PIC_UPPER || msk1 == PIC_LOWER) &&
-                    msk2 == (PIC_UPPER | PIC_LOWER))
-                        return 0;
-                if ((msk2 == PIC_UPPER || msk2 == PIC_LOWER) &&
-                    msk1 == (PIC_UPPER | PIC_LOWER))
-                        return 0;
-
-                /* If the events are fixed to different counters, OK.  */
-                if ((msk1 == PIC_UPPER && msk2 == PIC_LOWER) ||
-                    (msk1 == PIC_LOWER && msk2 == PIC_UPPER))
-                        return 0;
-
-                /* Otherwise, there is a conflict.  */
+        u8 msk0 = 0, msk1 = 0;
+        int idx0 = 0;
+
+        /* This case is possible when we are invoked from
+         * hw_perf_group_sched_in().
+         */
+        if (!n_ev)
+                return 0;
+
+        if (n_ev > perf_max_events)
+                return -1;
+
+        msk0 = perf_event_get_msk(events[0]);
+        if (n_ev == 1) {
+                if (msk0 & PIC_LOWER)
+                        idx0 = 1;
+                goto success;
+        }
+        BUG_ON(n_ev != 2);
+        msk1 = perf_event_get_msk(events[1]);
+
+        /* If both events can go on any counter, OK.  */
+        if (msk0 == (PIC_UPPER | PIC_LOWER) &&
+            msk1 == (PIC_UPPER | PIC_LOWER))
+                goto success;
+
+        /* If one event is limited to a specific counter,
+         * and the other can go on both, OK.
+         */
+        if ((msk0 == PIC_UPPER || msk0 == PIC_LOWER) &&
+            msk1 == (PIC_UPPER | PIC_LOWER)) {
+                if (msk0 & PIC_LOWER)
+                        idx0 = 1;
+                goto success;
         }
 
+        if ((msk1 == PIC_UPPER || msk1 == PIC_LOWER) &&
+            msk0 == (PIC_UPPER | PIC_LOWER)) {
+                if (msk1 & PIC_UPPER)
+                        idx0 = 1;
+                goto success;
+        }
+
+        /* If the events are fixed to different counters, OK.  */
+        if ((msk0 == PIC_UPPER && msk1 == PIC_LOWER) ||
+            (msk0 == PIC_LOWER && msk1 == PIC_UPPER)) {
+                if (msk0 & PIC_LOWER)
+                        idx0 = 1;
+                goto success;
+        }
+
+        /* Otherwise, there is a conflict.  */
         return -1;
+
+success:
+        evts[0]->hw.idx = idx0;
+        if (n_ev == 2)
+                evts[1]->hw.idx = idx0 ^ 1;
+        return 0;
 }
 
 static int check_excludes(struct perf_event **evts, int n_prev, int n_new)
@@ -822,7 +954,8 @@ static int check_excludes(struct perf_event **evts, int n_prev, int n_new)
 }
 
 static int collect_events(struct perf_event *group, int max_count,
-                          struct perf_event *evts[], unsigned long *events)
+                          struct perf_event *evts[], unsigned long *events,
+                          int *current_idx)
 {
         struct perf_event *event;
         int n = 0;
@@ -831,7 +964,8 @@ static int collect_events(struct perf_event *group, int max_count,
                 if (n >= max_count)
                         return -1;
                 evts[n] = group;
-                events[n++] = group->hw.event_base;
+                events[n] = group->hw.event_base;
+                current_idx[n++] = PIC_NO_INDEX;
         }
         list_for_each_entry(event, &group->sibling_list, group_entry) {
                 if (!is_software_event(event) &&
@@ -839,20 +973,100 @@ static int collect_events(struct perf_event *group, int max_count,
                         if (n >= max_count)
                                 return -1;
                         evts[n] = event;
-                        events[n++] = event->hw.event_base;
+                        events[n] = event->hw.event_base;
+                        current_idx[n++] = PIC_NO_INDEX;
                 }
         }
         return n;
 }
 
+static void event_sched_in(struct perf_event *event, int cpu)
+{
+        event->state = PERF_EVENT_STATE_ACTIVE;
+        event->oncpu = cpu;
+        event->tstamp_running += event->ctx->time - event->tstamp_stopped;
+        if (is_software_event(event))
+                event->pmu->enable(event);
+}
+
+int hw_perf_group_sched_in(struct perf_event *group_leader,
+                           struct perf_cpu_context *cpuctx,
+                           struct perf_event_context *ctx, int cpu)
+{
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        struct perf_event *sub;
+        int n0, n;
+
+        if (!sparc_pmu)
+                return 0;
+
+        n0 = cpuc->n_events;
+        n = collect_events(group_leader, perf_max_events - n0,
+                           &cpuc->event[n0], &cpuc->events[n0],
+                           &cpuc->current_idx[n0]);
+        if (n < 0)
+                return -EAGAIN;
+        if (check_excludes(cpuc->event, n0, n))
+                return -EINVAL;
+        if (sparc_check_constraints(cpuc->event, cpuc->events, n + n0))
+                return -EAGAIN;
+        cpuc->n_events = n0 + n;
+        cpuc->n_added += n;
+
+        cpuctx->active_oncpu += n;
+        n = 1;
+        event_sched_in(group_leader, cpu);
+        list_for_each_entry(sub, &group_leader->sibling_list, group_entry) {
+                if (sub->state != PERF_EVENT_STATE_OFF) {
+                        event_sched_in(sub, cpu);
+                        n++;
+                }
+        }
+        ctx->nr_active += n;
+
+        return 1;
+}
+
+static int sparc_pmu_enable(struct perf_event *event)
+{
+        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+        int n0, ret = -EAGAIN;
+        unsigned long flags;
+
+        local_irq_save(flags);
+        perf_disable();
+
+        n0 = cpuc->n_events;
+        if (n0 >= perf_max_events)
+                goto out;
+
+        cpuc->event[n0] = event;
+        cpuc->events[n0] = event->hw.event_base;
+        cpuc->current_idx[n0] = PIC_NO_INDEX;
+
+        if (check_excludes(cpuc->event, n0, 1))
+                goto out;
+        if (sparc_check_constraints(cpuc->event, cpuc->events, n0 + 1))
+                goto out;
+
+        cpuc->n_events++;
+        cpuc->n_added++;
+
+        ret = 0;
+out:
+        perf_enable();
+        local_irq_restore(flags);
+        return ret;
+}
+
 static int __hw_perf_event_init(struct perf_event *event)
 {
         struct perf_event_attr *attr = &event->attr;
         struct perf_event *evts[MAX_HWEVENTS];
         struct hw_perf_event *hwc = &event->hw;
         unsigned long events[MAX_HWEVENTS];
+        int current_idx_dmy[MAX_HWEVENTS];
         const struct perf_event_map *pmap;
-        u64 enc;
         int n;
 
         if (atomic_read(&nmi_active) < 0)
@@ -869,10 +1083,7 @@ static int __hw_perf_event_init(struct perf_event *event)
         } else
                 return -EOPNOTSUPP;
 
-        /* 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'.
-         */
+        /* We save the enable bits in the config_base.  */
         hwc->config_base = sparc_pmu->irq_bit;
         if (!attr->exclude_user)
                 hwc->config_base |= PCR_UTRACE;
@@ -883,13 +1094,11 @@ static int __hw_perf_event_init(struct perf_event *event)
 
         hwc->event_base = perf_event_encode(pmap);
 
-        enc = pmap->encoding;
-
         n = 0;
         if (event->group_leader != event) {
                 n = collect_events(event->group_leader,
                                    perf_max_events - 1,
-                                   evts, events);
+                                   evts, events, current_idx_dmy);
                 if (n < 0)
                         return -EINVAL;
         }
@@ -899,9 +1108,11 @@ static int __hw_perf_event_init(struct perf_event *event)
         if (check_excludes(evts, n, 1))
                 return -EINVAL;
 
-        if (sparc_check_constraints(events, n + 1))
+        if (sparc_check_constraints(evts, events, n + 1))
                 return -EINVAL;
 
+        hwc->idx = PIC_NO_INDEX;
+
         /* Try to do all error checking before this point, as unwinding
          * state after grabbing the PMC is difficult.
          */
@@ -914,15 +1125,6 @@ static int __hw_perf_event_init(struct perf_event *event)
                 atomic64_set(&hwc->period_left, hwc->sample_period);
         }
 
-        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;
 }
 
@@ -972,7 +1174,7 @@ static int __kprobes perf_event_nmi_handler(struct notifier_block *self,
         struct perf_sample_data data;
         struct cpu_hw_events *cpuc;
         struct pt_regs *regs;
-        int idx;
+        int i;
 
         if (!atomic_read(&active_events))
                 return NOTIFY_DONE;
@@ -1001,13 +1203,12 @@ static int __kprobes perf_event_nmi_handler(struct notifier_block *self,
         if (sparc_pmu->irq_bit)
                 pcr_ops->write(cpuc->pcr);
 
-        for (idx = 0; idx < MAX_HWEVENTS; idx++) {
-                struct perf_event *event = cpuc->events[idx];
+        for (i = 0; i < cpuc->n_events; i++) {
+                struct perf_event *event = cpuc->event[i];
+                int idx = cpuc->current_idx[i];
                 struct hw_perf_event *hwc;
                 u64 val;
 
-                if (!test_bit(idx, cpuc->active_mask))
-                        continue;
                 hwc = &event->hw;
                 val = sparc_perf_event_update(event, hwc, idx);
                 if (val & (1ULL << 31))
@@ -1059,10 +1260,8 @@ void __init init_hw_perf_events(void)
 
         pr_cont("Supported PMU type is '%s'\n", sparc_pmu_type);
 
-        /* All sparc64 PMUs currently have 2 events.  But this simple
-         * driver only supports one active event at a time.
-         */
-        perf_max_events = 1;
+        /* All sparc64 PMUs currently have 2 events.  */
+        perf_max_events = 2;
 
         register_die_notifier(&perf_event_nmi_notifier);
 }