From: Mathieu Poirier <mathieu.poirier@linaro.org> To: Leo Yan <leo.yan@linaro.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, Suzuki K Poulose <suzuki.poulose@arm.com>, Mark Rutland <mark.rutland@arm.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, Mike Leach <mike.leach@linaro.org>, Coresight ML <coresight@lists.linaro.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com> Subject: Re: [PATCH v3 1/6] perf cs-etm: Fix unsigned variable comparison to zero Date: Fri, 11 Oct 2019 14:16:06 -0600 [thread overview] Message-ID: <20191011201606.GC13688@xps15> (raw) In-Reply-To: <20191005091614.11635-2-leo.yan@linaro.org> On Sat, Oct 05, 2019 at 05:16:09PM +0800, Leo Yan wrote: > 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@linaro.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) In Suzuki's reply there was two choices, 1) move the while(offset > 0) to while (offset) or change the type of @offset to an s64. Here we know offset can't be negative because of the tidq->period_instructions >= etm->instructions_sample_period in function cs_etm__sample(). As such I think option #1 is the right way to deal with this rather than changing the type of the variable. Mathieu > { > 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 >
WARNING: multiple messages have this Message-ID (diff)
From: Mathieu Poirier <mathieu.poirier@linaro.org> To: Leo Yan <leo.yan@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Coresight ML <coresight@lists.linaro.org>, linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo <acme@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>, linux-arm-kernel@lists.infradead.org, Mike Leach <mike.leach@linaro.org> Subject: Re: [PATCH v3 1/6] perf cs-etm: Fix unsigned variable comparison to zero Date: Fri, 11 Oct 2019 14:16:06 -0600 [thread overview] Message-ID: <20191011201606.GC13688@xps15> (raw) In-Reply-To: <20191005091614.11635-2-leo.yan@linaro.org> On Sat, Oct 05, 2019 at 05:16:09PM +0800, Leo Yan wrote: > 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@linaro.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) In Suzuki's reply there was two choices, 1) move the while(offset > 0) to while (offset) or change the type of @offset to an s64. Here we know offset can't be negative because of the tidq->period_instructions >= etm->instructions_sample_period in function cs_etm__sample(). As such I think option #1 is the right way to deal with this rather than changing the type of the variable. Mathieu > { > 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 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-10-11 20:16 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-05 9:16 [PATCH v3 0/6] perf cs-etm: Support thread stack and callchain Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-05 9:16 ` [PATCH v3 1/6] perf cs-etm: Fix unsigned variable comparison to zero Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-11 20:16 ` Mathieu Poirier [this message] 2019-10-11 20:16 ` Mathieu Poirier 2019-10-22 5:10 ` Leo Yan 2019-10-22 5:10 ` Leo Yan 2019-10-22 23:36 ` Mike Leach 2019-10-22 23:36 ` Mike Leach 2019-10-23 6:49 ` Leo Yan 2019-10-23 6:49 ` Leo Yan 2019-10-05 9:16 ` [PATCH v3 2/6] perf cs-etm: Refactor instruction size handling Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-05 9:16 ` [PATCH v3 3/6] perf cs-etm: Support thread stack Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-11 17:53 ` Mathieu Poirier 2019-10-11 17:53 ` Mathieu Poirier 2019-10-15 3:33 ` Leo Yan 2019-10-15 3:33 ` Leo Yan 2019-10-22 5:03 ` Leo Yan 2019-10-22 5:03 ` Leo Yan 2019-10-28 22:43 ` Mathieu Poirier 2019-10-28 22:43 ` Mathieu Poirier 2019-10-29 4:11 ` Leo Yan 2019-10-29 4:11 ` Leo Yan 2019-10-05 9:16 ` [PATCH v3 4/6] perf cs-etm: Support branch filter Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-05 9:16 ` [PATCH v3 5/6] perf cs-etm: Support callchain for instruction sample Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-11 19:59 ` Mathieu Poirier 2019-10-11 19:59 ` Mathieu Poirier 2019-10-05 9:16 ` [PATCH v3 6/6] perf cs-etm: Synchronize instruction sample with the thread stack Leo Yan 2019-10-05 9:16 ` Leo Yan 2019-10-11 20:17 ` Mathieu Poirier 2019-10-11 20:17 ` Mathieu Poirier 2019-10-15 3:44 ` Leo Yan 2019-10-15 3:44 ` Leo Yan 2019-10-22 4:50 ` Leo Yan 2019-10-22 4:50 ` Leo Yan
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