linux-kernel - [PATCH v3 1/6] perf cs-etm: Fix unsigned variable comparison to zero

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Date:   Sat,  5 Oct 2019 17:16:09 +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>,
        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,
        Mike Leach <mike.leach@...aro.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v3 1/6] perf cs-etm: Fix unsigned variable comparison to zero

If the u64 variable 'offset' is a negative integer, comparison it with
bigger than zero is always going to be true because it is unsigned.
Fix this by using s64 type for variable 'offset'.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/util/cs-etm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 4ba0f871f086..4bc2d9709d4f 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -940,7 +940,7 @@ u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
 static inline u64 cs_etm__instr_addr(struct cs_etm_queue *etmq,
 				     u64 trace_chan_id,
 				     const struct cs_etm_packet *packet,
-				     u64 offset)
+				     s64 offset)
 {
 	if (packet->isa == CS_ETM_ISA_T32) {
 		u64 addr = packet->start_addr;
@@ -1372,7 +1372,7 @@ static int cs_etm__sample(struct cs_etm_queue *etmq,
 		 * sample is reported as though instruction has just been
 		 * executed, but PC has not advanced to next instruction)
 		 */
-		u64 offset = (instrs_executed - instrs_over - 1);
+		s64 offset = (instrs_executed - instrs_over - 1);
 		u64 addr = cs_etm__instr_addr(etmq, trace_chan_id,
 					      tidq->packet, offset);
 
-- 
2.17.1