Re: [PATCH 1/2] perf cs-etm: Fix corrupt data after perf inject from

From
Leo Yan <hidden>
Date
2020-09-02 00:39:44
Also in
lkml
Reply to
Arnaldo Carvalho de Melo, 2020-09-01
Hi Arnaldo,

On Tue, Sep 01, 2020 at 11:54:32AM -0300, Arnaldo Carvalho de Melo wrote:
Em Mon, Aug 31, 2020 at 08:04:32AM +0800, Leo Yan escreveu:
quoted
Hi Mathieu,

On Thu, Aug 27, 2020 at 02:53:54PM -0600, Mathieu Poirier wrote:
quoted
Hi Leo and Al,

On Wed, Aug 19, 2020 at 04:47:50PM +0800, Leo Yan wrote:
quoted
From: Al Grant <redacted>

Commit 42bbabed09ce ("perf tools: Add hw_idx in struct branch_stack")
changed the format of branch stacks in perf samples. When samples use
this new format, a flag must be set in the corresponding event.
Synthesized branch stacks generated from CoreSight ETM trace were using
the new format, but not setting the event attribute, leading to
consumers seeing corrupt data. This patch fixes the issue by setting the
event attribute to indicate use of the new format.

Fixes: 42bbabed09ce ("perf tools: Add hw_idx in struct branch_stack")
Signed-off-by: Al Grant <redacted>
Reviewed-by: Andrea Brunato <redacted>
Signed-off-by: Leo Yan <redacted>
---
 tools/perf/util/cs-etm.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index c283223fb31f..a2a369e2fbb6 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1344,8 +1344,15 @@ static int cs_etm__synth_events(struct cs_etm_auxtrace *etm,
 		attr.sample_type &= ~(u64)PERF_SAMPLE_ADDR;
 	}
 
-	if (etm->synth_opts.last_branch)
+	if (etm->synth_opts.last_branch) {
 		attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
+		/*
+		 * We don't use the hardware index, but the sample generation
+		 * code uses the new format branch_stack with this field,
+		 * so the event attributes must indicate that it's present.
+		 */
+		attr.branch_sample_type |= PERF_SAMPLE_BRANCH_HW_INDEX;
+	}
I've see this patch before...  I thought it had been merged - what happened?
This patch before has been sent by Al to CoreSight mailing list but has
not sent to LKML, this is why I resent it to LKML in case it's missed.
So, was it Acked on the CoreSight mailing list? Are we missing any
Acked-by or Reviewed-by for this 1/2 patch as we got for 2/2?
The CoreSight mailing list has some discussion for this patch set,
when respin this patch set, I confirmed we don't miss any 'Acked' or
'Reviewed' tags.

Thanks,
Leo

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Thread (11 messages) 11 messages, 4 authors, last reply 2020-09-02
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