linux-kernel - [PATCH v5 8/9] perf thread: Add helper to get top return address

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Date:   Thu, 20 Feb 2020 13:27:00 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mark Rutland <mark.rutland@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Robert Walker <robert.walker@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Coresight ML <coresight@...ts.linaro.org>
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v5 8/9] perf thread: Add helper to get top return address

For the instruction emulation or single step in kernel, when return to
the user space, the return address is not possible to be the same with
the ret_addr in thread stack.

This patch adds a helper to read out the top return address from thread
stack, this can be used for specific calibration in up case.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/util/thread-stack.c | 10 ++++++++++
 tools/perf/util/thread-stack.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index 0885967d5bc3..60cd6fdca8de 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -497,6 +497,16 @@ void thread_stack__sample(struct thread *thread, int cpu,
 	chain->nr = i;
 }
 
+u64 thread_stack__get_top_ret_addr(struct thread *thread, int cpu)
+{
+	struct thread_stack *ts = thread__stack(thread, cpu);
+
+	if (!ts || !ts->cnt)
+		return UINT64_MAX;
+
+	return ts->stack[ts->cnt--].ret_addr;
+}
+
 struct call_return_processor *
 call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data),
 			   void *data)
diff --git a/tools/perf/util/thread-stack.h b/tools/perf/util/thread-stack.h
index e1ec5a58f1b2..b9d07a3be6c2 100644
--- a/tools/perf/util/thread-stack.h
+++ b/tools/perf/util/thread-stack.h
@@ -88,6 +88,7 @@ void thread_stack__sample(struct thread *thread, int cpu, struct ip_callchain *c
 int thread_stack__flush(struct thread *thread);
 void thread_stack__free(struct thread *thread);
 size_t thread_stack__depth(struct thread *thread, int cpu);
+u64 thread_stack__get_top_ret_addr(struct thread *thread, int cpu);
 
 struct call_return_processor *
 call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data),
-- 
2.17.1