linux-kernel - [PATCH 2/9] perf report: Remove the first overflow check for branch counters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240703200356.852727-3-kan.liang@linux.intel.com>
Date: Wed,  3 Jul 2024 13:03:49 -0700
From: kan.liang@...ux.intel.com
To: acme@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com,
	peterz@...radead.org,
	mingo@...nel.org,
	linux-kernel@...r.kernel.org
Cc: adrian.hunter@...el.com,
	ak@...ux.intel.com,
	eranian@...gle.com,
	Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 2/9] perf report: Remove the first overflow check for branch counters

From: Kan Liang <kan.liang@...ux.intel.com>

A false overflow warning is triggered if a sample doesn't have any LBRs
recorded and the branch counters feature is enabled.

The current code does OVERFLOW_CHECK_u64() at the very beginning when
reading the information of branch counters. It assumes that there is at
least one LBR in the PEBS record. But it is a valid case that 0 LBR is
recorded especially in a high context switch.

Remove the OVERFLOW_CHECK_u64(). The later OVERFLOW_CHECK() should be
good enough to check the overflow when reading the information of the
branch counters.

Fixes: 9fbb4b02302b ("perf tools: Add branch counter knob")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/util/evsel.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index bc603193c477..a5dd031c9080 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2810,8 +2810,6 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
 		array = (void *)array + sz;

 		if (evsel__has_branch_counters(evsel)) {
-			OVERFLOW_CHECK_u64(array);
-
 			data->branch_stack_cntr = (u64 *)array;
 			sz = data->branch_stack->nr * sizeof(u64);

-- 
2.38.1