perf/x86/intel/bts: Make sure debug store is valid

[cascardo/linux.git] / arch / x86 / events / intel / bts.c

diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 61e1d71..6ff66ef 100644 (file)
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -378,8 +378,6 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
                return 0;
 
        head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
-       if (WARN_ON_ONCE(head != local_read(&buf->head)))
-               return -EINVAL;
 
        phys = &buf->buf[buf->cur_buf];
        space = phys->offset + phys->displacement + phys->size - head;
@@ -446,26 +444,37 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
 
 int intel_bts_interrupt(void)
 {
+       struct debug_store *ds = this_cpu_ptr(&cpu_hw_events)->ds;
        struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
        struct perf_event *event = bts->handle.event;
        struct bts_buffer *buf;
        s64 old_head;
-       int err = -ENOSPC;
+       int err = -ENOSPC, handled = 0;
+
+       /*
+        * The only surefire way of knowing if this NMI is ours is by checking
+        * the write ptr against the PMI threshold.
+        */
+       if (ds && (ds->bts_index >= ds->bts_interrupt_threshold))
+               handled = 1;
 
        /*
         * this is wrapped in intel_bts_enable_local/intel_bts_disable_local,
         * so we can only be INACTIVE or STOPPED
         */
        if (READ_ONCE(bts->state) == BTS_STATE_STOPPED)
-               return 0;
+               return handled;
 
        buf = perf_get_aux(&bts->handle);
+       if (!buf)
+               return handled;
+
        /*
         * Skip snapshot counters: they don't use the interrupt, but
         * there's no other way of telling, because the pointer will
         * keep moving
         */
-       if (!buf || buf->snapshot)
+       if (buf->snapshot)
                return 0;
 
        old_head = local_read(&buf->head);
@@ -473,7 +482,7 @@ int intel_bts_interrupt(void)
 
        /* no new data */
        if (old_head == local_read(&buf->head))
-               return 0;
+               return handled;
 
        perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
                            !!local_xchg(&buf->lost, 0));