From 1f7958109a19db599e668a6105bd173f12a441df Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Fri, 23 Sep 2016 17:38:41 +0300 Subject: perf intel-pt: Fix snapshot overlap detection decoder errors commit 810c398bc09b2f2dfde52a7d2483a710612c5fb8 upstream. Fix occasional decoder errors decoding trace data collected in snapshot mode. Snapshot mode can take successive snapshots of trace which might overlap. The decoder checks whether there is an overlap but only looks at the current and previous buffer. However buffers that do not contain synchronization (i.e. PSB) packets cannot be decoded or used for overlap checking. That means the decoder actually needs to check overlaps between the current buffer and the previous buffer that contained usable data. Make that change. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Mathieu Poirier Link: http://lkml.kernel.org/r/1474641528-18776-10-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman --- tools/perf/util/intel-pt.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c index 551ff6f640be..b2878d2b2d67 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c @@ -241,7 +241,7 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) } queue = &ptq->pt->queues.queue_array[ptq->queue_nr]; - +next: buffer = auxtrace_buffer__next(queue, buffer); if (!buffer) { if (old_buffer) @@ -264,9 +264,6 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) intel_pt_do_fix_overlap(ptq->pt, old_buffer, buffer)) return -ENOMEM; - if (old_buffer) - auxtrace_buffer__drop_data(old_buffer); - if (buffer->use_data) { b->len = buffer->use_size; b->buf = buffer->use_data; @@ -276,6 +273,16 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) } b->ref_timestamp = buffer->reference; + /* + * If in snapshot mode and the buffer has no usable data, get next + * buffer and again check overlap against old_buffer. + */ + if (ptq->pt->snapshot_mode && !b->len) + goto next; + + if (old_buffer) + auxtrace_buffer__drop_data(old_buffer); + if (!old_buffer || ptq->pt->sampling_mode || (ptq->pt->snapshot_mode && !buffer->consecutive)) { b->consecutive = false; -- cgit v1.2.3