5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Leo Yan <leo.yan@arm.com>
[ Upstream commit ea5075e3776846d4941dddf1549426ebd3feb81f ]
Perf resets the CoreSight decoder when moving to a new AUX trace buffer,
this causes trace discontinunity globally.
For callchain synthesis, keeping thread-stack state after decoder reset
can leave stale call/return history attached to threads that are decoded
later, producing incorrect synthesized callchains.
Flush all host thread stacks after a decoder reset. When virtualization
is present, flush the guest thread stacks as well.
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Stable-dep-of: ec99be8a31db ("perf cs-etm: Avoid truncating AUX buffer sizes to int")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/cs-etm.c | 45 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 6fa698186f0b6..be5a2e2d226d8 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1637,6 +1637,45 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq,
return 0;
}
+
+static int cs_etm__flush_stack_cb(struct thread *thread,
+ void *data __maybe_unused)
+{
+ thread_stack__flush(thread);
+ return 0;
+}
+
+static void cs_etm__flush_machine_stack(struct cs_etm_queue *etmq, pid_t pid)
+{
+ struct machine *machine;
+
+ machine = machines__find(&etmq->etm->session->machines, pid);
+ if (machine)
+ machine__for_each_thread(machine, cs_etm__flush_stack_cb, NULL);
+}
+
+static void cs_etm__flush_all_stack(struct cs_etm_queue *etmq)
+{
+ enum cs_etm_pid_fmt pid_fmt = cs_etm__get_pid_fmt(etmq);
+
+ if (!etmq->etm->synth_opts.last_branch)
+ return;
+
+ switch (pid_fmt) {
+ case CS_ETM_PIDFMT_CTXTID2:
+ /* Clear the guest stack if virtualization is supported */
+ cs_etm__flush_machine_stack(etmq, DEFAULT_GUEST_KERNEL_ID);
+ fallthrough;
+ case CS_ETM_PIDFMT_CTXTID:
+ cs_etm__flush_machine_stack(etmq, HOST_KERNEL_ID);
+ break;
+ case CS_ETM_PIDFMT_NONE:
+ default:
+ break;
+
+ }
+}
+
/*
* cs_etm__get_data_block: Fetch a block from the auxtrace_buffer queue
* if need be.@@ -1659,6 +1698,12 @@ static int cs_etm__get_data_block(struct cs_etm_queue *etmq)
ret = cs_etm_decoder__reset(etmq->decoder);
if (ret)
return ret;
+
+ /*
+ * Since the decoder is reset, this causes a global trace
+ * discontinuity. Flush all thread stacks.
+ */
+ cs_etm__flush_all_stack(etmq);
}
return etmq->buf_len;
--
2.53.0