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From:   Leo Yan <leo.yan@linaro.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Mike Leach <mike.leach@linaro.org>,
        Robert Walker <robert.walker@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Coresight ML <coresight@lists.linaro.org>
Cc:     Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v5 8/9] perf thread: Add helper to get top return address
Date:   Thu, 20 Feb 2020 13:27:00 +0800
Message-Id: <20200220052701.7754-9-leo.yan@linaro.org>
In-Reply-To: <20200220052701.7754-1-leo.yan@linaro.org>
References: <20200220052701.7754-1-leo.yan@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@linaro.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