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Date: Wed, 31 Oct 2018 11:26:47 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
linux-kernel@...r.kernel.org, leo.yan@...aro.org,
David Miller <davem@...emloft.net>,
Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: Re: [PATCH 4/5] perf intel-pt: Insert callchain context into
synthesized callchains
Em Wed, Oct 31, 2018 at 04:15:26PM +0200, Adrian Hunter escreveu:
> On 31/10/18 3:28 PM, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Oct 31, 2018 at 11:10:42AM +0200, Adrian Hunter escreveu:
> >> In the absence of a fallback, callchains must encode also the callchain
> >> context. Do that now there is no fallback.
> >
> > So, this one is independent of the first 3 patches, right?
>
> Yes. I was just going to test it separately when I noticed I had
> screwed up my earlier testing. When I re-tested I discovered this patch
> has an off-by-one error:
>
> diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
> index afdf36852ac8..61a4286a74dc 100644
> --- a/tools/perf/util/thread-stack.c
> +++ b/tools/perf/util/thread-stack.c
> @@ -337,7 +337,7 @@ void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
>
> last_context = context;
>
> - for (i = 2, j = 0; i < sz && j < thread->ts->cnt; i++, j++) {
> + for (i = 2, j = 1; i < sz && j <= thread->ts->cnt; i++, j++) {
> ip = thread->ts->stack[thread->ts->cnt - j].ret_addr;
> context = callchain_context(ip, kernel_start);
> if (context != last_context) {
>
> Shall I send V2?
No need, I can fix this here
> > So, this one is independent of the first 3 patches, right? Ok, applying
> > it first, I'll relook the first ones next.
> >
> > - Arnaldo
> >
> >> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> >> Cc: stable@...r.kernel.org # 4.19
> >> ---
> >> tools/perf/util/intel-pt.c | 6 +++--
> >> tools/perf/util/thread-stack.c | 44 +++++++++++++++++++++++++++-------
> >> tools/perf/util/thread-stack.h | 2 +-
> >> 3 files changed, 40 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> >> index ffa385a029b3..60732213d16a 100644
> >> --- a/tools/perf/util/intel-pt.c
> >> +++ b/tools/perf/util/intel-pt.c
> >> @@ -759,7 +759,8 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt,
> >> if (pt->synth_opts.callchain) {
> >> size_t sz = sizeof(struct ip_callchain);
> >>
> >> - sz += pt->synth_opts.callchain_sz * sizeof(u64);
> >> + /* Add 1 to callchain_sz for callchain context */
> >> + sz += (pt->synth_opts.callchain_sz + 1) * sizeof(u64);
> >> ptq->chain = zalloc(sz);
> >> if (!ptq->chain)
> >> goto out_free;
> >> @@ -1160,7 +1161,8 @@ static void intel_pt_prep_sample(struct intel_pt *pt,
> >>
> >> if (pt->synth_opts.callchain) {
> >> thread_stack__sample(ptq->thread, ptq->chain,
> >> - pt->synth_opts.callchain_sz, sample->ip);
> >> + pt->synth_opts.callchain_sz + 1,
> >> + sample->ip, pt->kernel_start);
> >> sample->callchain = ptq->chain;
> >> }
> >>
> >> diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
> >> index c091635bf7dc..afdf36852ac8 100644
> >> --- a/tools/perf/util/thread-stack.c
> >> +++ b/tools/perf/util/thread-stack.c
> >> @@ -310,20 +310,46 @@ void thread_stack__free(struct thread *thread)
> >> }
> >> }
> >>
> >> +static inline u64 callchain_context(u64 ip, u64 kernel_start)
> >> +{
> >> + return ip < kernel_start ? PERF_CONTEXT_USER : PERF_CONTEXT_KERNEL;
> >> +}
> >> +
> >> void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
> >> - size_t sz, u64 ip)
> >> + size_t sz, u64 ip, u64 kernel_start)
> >> {
> >> - size_t i;
> >> + u64 context = callchain_context(ip, kernel_start);
> >> + u64 last_context;
> >> + size_t i, j;
> >>
> >> - if (!thread || !thread->ts)
> >> - chain->nr = 1;
> >> - else
> >> - chain->nr = min(sz, thread->ts->cnt + 1);
> >> + if (sz < 2) {
> >> + chain->nr = 0;
> >> + return;
> >> + }
> >>
> >> - chain->ips[0] = ip;
> >> + chain->ips[0] = context;
> >> + chain->ips[1] = ip;
> >> +
> >> + if (!thread || !thread->ts) {
> >> + chain->nr = 2;
> >> + return;
> >> + }
> >> +
> >> + last_context = context;
> >> +
> >> + for (i = 2, j = 0; i < sz && j < thread->ts->cnt; i++, j++) {
> >> + ip = thread->ts->stack[thread->ts->cnt - j].ret_addr;
> >> + context = callchain_context(ip, kernel_start);
> >> + if (context != last_context) {
> >> + if (i >= sz - 1)
> >> + break;
> >> + chain->ips[i++] = context;
> >> + last_context = context;
> >> + }
> >> + chain->ips[i] = ip;
> >> + }
> >>
> >> - for (i = 1; i < chain->nr; i++)
> >> - chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;
> >> + chain->nr = i;
> >> }
> >>
> >> struct call_return_processor *
> >> diff --git a/tools/perf/util/thread-stack.h b/tools/perf/util/thread-stack.h
> >> index b7e41c4ebfdd..f97c00a8c251 100644
> >> --- a/tools/perf/util/thread-stack.h
> >> +++ b/tools/perf/util/thread-stack.h
> >> @@ -84,7 +84,7 @@ int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
> >> u64 to_ip, u16 insn_len, u64 trace_nr);
> >> void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr);
> >> void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
> >> - size_t sz, u64 ip);
> >> + size_t sz, u64 ip, u64 kernel_start);
> >> int thread_stack__flush(struct thread *thread);
> >> void thread_stack__free(struct thread *thread);
> >> size_t thread_stack__depth(struct thread *thread);
> >> --
> >> 2.17.1
> >
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