[PATCH 2/9] perf thread-stack: Report branch stack hw_idx as not available
Amir Ayupov <[email protected]>
| Newsgroups | org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-doc,org.kernel.vger.linux-perf-users |
|---|---|
| Message-ID | <[email protected]> |
thread_stack__br_sample() and thread_stack__br_sample_late() fill a caller-supplied branch_stack that is typically allocated with zalloc(), leaving hw_idx as 0. Zero is a valid hardware index, so consumers that honour PERF_SAMPLE_BRANCH_HW_INDEX see a reconstructed branch stack claiming to start at LBR TOS entry 0. These branch stacks are reconstructed from instruction trace and have no hardware index at all. Set hw_idx to -1ULL, which is the established way to say "not available" and matches what intel-pt and cs-etm already put in the branch stacks they synthesise directly. Signed-off-by: Amir Ayupov <[email protected]> --- tools/perf/util/thread-stack.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c index c5ce741b07446..1a3dffa83bde2 100644 --- a/tools/perf/util/thread-stack.c +++ b/tools/perf/util/thread-stack.c @@ -624,6 +624,7 @@ void thread_stack__br_sample(struct thread *thread, int cpu, unsigned int nr; dst->nr = 0; + dst->hw_idx = -1ULL; if (!ts) return; @@ -686,6 +687,7 @@ void thread_stack__br_sample_late(struct thread *thread, int cpu, bool start = false; dst->nr = 0; + dst->hw_idx = -1ULL; if (!ts) return; -- 2.52.0