perf/x86/intel/pt: Untangle pt_buffer_reset_markers()

[deliverable/linux.git] / arch / x86 / kernel / cpu / perf_event_intel_pt.c

diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index ffe666c2c6b58657b5895948a2e7d69f95223521..5b804f96ad66c5639c4fc62a4cb9fdaa2f00a744 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -615,7 +615,8 @@ static int pt_buffer_reset_markers(struct pt_buffer *buf,
                                   struct perf_output_handle *handle)
 
 {
-       unsigned long idx, npages, end;
+       unsigned long head = local64_read(&buf->head);
+       unsigned long idx, npages, wakeup;
 
        if (buf->snapshot)
                return 0;
@@ -634,17 +635,26 @@ static int pt_buffer_reset_markers(struct pt_buffer *buf,
        buf->topa_index[buf->stop_pos]->stop = 0;
        buf->topa_index[buf->intr_pos]->intr = 0;
 
-       if (pt_cap_get(PT_CAP_topa_multiple_entries)) {
-               npages = (handle->size + 1) >> PAGE_SHIFT;
-               end = (local64_read(&buf->head) >> PAGE_SHIFT) + npages;
-               /*if (end > handle->wakeup >> PAGE_SHIFT)
-                 end = handle->wakeup >> PAGE_SHIFT;*/
-               idx = end & (buf->nr_pages - 1);
-               buf->stop_pos = idx;
-               idx = (local64_read(&buf->head) >> PAGE_SHIFT) + npages - 1;
-               idx &= buf->nr_pages - 1;
-               buf->intr_pos = idx;
-       }
+       /* how many pages till the STOP marker */
+       npages = handle->size >> PAGE_SHIFT;
+
+       /* if it's on a page boundary, fill up one more page */
+       if (!offset_in_page(head + handle->size + 1))
+               npages++;
+
+       idx = (head >> PAGE_SHIFT) + npages;
+       idx &= buf->nr_pages - 1;
+       buf->stop_pos = idx;
+
+       wakeup = handle->wakeup >> PAGE_SHIFT;
+
+       /* in the worst case, wake up the consumer one page before hard stop */
+       idx = (head >> PAGE_SHIFT) + npages - 1;
+       if (idx > wakeup)
+               idx = wakeup;
+
+       idx &= buf->nr_pages - 1;
+       buf->intr_pos = idx;
 
        buf->topa_index[buf->stop_pos]->stop = 1;
        buf->topa_index[buf->intr_pos]->intr = 1;