linux-kernel - [PATCH 1/3] perf/x86: Fix low freq setting issue

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-next>] [day] [month] [year] [list]

Message-Id: <20250117151913.3043942-1-kan.liang@linux.intel.com>
Date: Fri, 17 Jan 2025 07:19:11 -0800
From: kan.liang@...ux.intel.com
To: peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Cc: ak@...ux.intel.com,
	ravi.bangoria@....com,
	jolsa@...hat.com,
	Kan Liang <kan.liang@...ux.intel.com>,
	stable@...r.kernel.org
Subject: [PATCH 1/3] perf/x86: Fix low freq setting issue

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

Perf doesn't work with a low freq.

perf record -e cpu_core/instructions/ppp -F 120
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument)
for event (cpu_core/instructions/ppp).
"dmesg | grep -i perf" may provide additional information.

The limit_period() check avoids a low sampling period on a counter. It
doesn't intend to limit the frequency.
The check in the x86_pmu_hw_config() should be limited to non-freq mode.
The attr.sample_period and attr.sample_freq are union. The
attr.sample_period should not be used to indicate the freq mode.

Fixes: c46e665f0377 ("perf/x86: Add INST_RETIRED.ALL workarounds")
Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@amd.com/
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Ravi Bangoria <ravi.bangoria@....com>
Cc: stable@...r.kernel.org
---
 arch/x86/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 7b6430e5a77b..20ad5cca6ad2 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -630,7 +630,7 @@ int x86_pmu_hw_config(struct perf_event *event)
 	if (event->attr.type == event->pmu->type)
 		event->hw.config |= x86_pmu_get_event_config(event);
 
-	if (event->attr.sample_period && x86_pmu.limit_period) {
+	if (!event->attr.freq && x86_pmu.limit_period) {
 		s64 left = event->attr.sample_period;
 		x86_pmu.limit_period(event, &left);
 		if (left > event->attr.sample_period)
-- 
2.38.1