sparc64: Add initial perf event conflict resolution and checks.

Cribbed from powerpc code, as usual. :-)

Currently it is only used to validate that all counters
have the same user/kernel/hv attributes.

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

1 files changed, 77 insertions, 5 deletions

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 9541b456c3ee..919952498155 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -713,12 +713,66 @@ static void hw_perf_event_destroy(struct perf_event *event)
         perf_event_release_pmc();
 }
 
+static int check_excludes(struct perf_event **evts, int n_prev, int n_new)
+{
+        int eu = 0, ek = 0, eh = 0;
+        struct perf_event *event;
+        int i, n, first;
+
+        n = n_prev + n_new;
+        if (n <= 1)
+                return 0;
+
+        first = 1;
+        for (i = 0; i < n; i++) {
+                event = evts[i];
+                if (first) {
+                        eu = event->attr.exclude_user;
+                        ek = event->attr.exclude_kernel;
+                        eh = event->attr.exclude_hv;
+                        first = 0;
+                } else if (event->attr.exclude_user != eu ||
+                           event->attr.exclude_kernel != ek ||
+                           event->attr.exclude_hv != eh) {
+                        return -EAGAIN;
+                }
+        }
+
+        return 0;
+}
+
+static int collect_events(struct perf_event *group, int max_count,
+                          struct perf_event *evts[], u64 *events)
+{
+        struct perf_event *event;
+        int n = 0;
+
+        if (!is_software_event(group)) {
+                if (n >= max_count)
+                        return -1;
+                evts[n] = group;
+                events[n++] = group->hw.config;
+        }
+        list_for_each_entry(event, &group->sibling_list, group_entry) {
+                if (!is_software_event(event) &&
+                    event->state != PERF_EVENT_STATE_OFF) {
+                        if (n >= max_count)
+                                return -1;
+                        evts[n] = event;
+                        events[n++] = event->hw.config;
+                }
+        }
+        return n;
+}
+
 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;
         const struct perf_event_map *pmap;
-        u64 enc;
+        u64 enc, events[MAX_HWEVENTS];
+        int n;
 
         if (atomic_read(&nmi_active) < 0)
                 return -ENODEV;
@@ -734,9 +788,6 @@ static int __hw_perf_event_init(struct perf_event *event)
         } else
                 return -EOPNOTSUPP;
 
-        perf_event_grab_pmc();
-        event->destroy = hw_perf_event_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'.
@@ -749,13 +800,34 @@ static int __hw_perf_event_init(struct perf_event *event)
         if (!attr->exclude_hv)
                 hwc->config_base |= sparc_pmu->hv_bit;
 
+        enc = pmap->encoding;
+
+        n = 0;
+        if (event->group_leader != event) {
+                n = collect_events(event->group_leader,
+                                   perf_max_events - 1,
+                                   evts, events);
+                if (n < 0)
+                        return -EINVAL;
+        }
+        events[n] = enc;
+        evts[n] = event;
+
+        if (check_excludes(evts, n, 1))
+                return -EINVAL;
+
+        /* Try to do all error checking before this point, as unwinding
+         * state after grabbing the PMC is difficult.
+         */
+        perf_event_grab_pmc();
+        event->destroy = hw_perf_event_destroy;
+
         if (!hwc->sample_period) {
                 hwc->sample_period = MAX_PERIOD;
                 hwc->last_period = hwc->sample_period;
                 atomic64_set(&hwc->period_left, hwc->sample_period);
         }
 
-        enc = pmap->encoding;
         if (pmap->pic_mask & PIC_UPPER) {
                 hwc->idx = PIC_UPPER_INDEX;
                 enc <<= sparc_pmu->upper_shift;