6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kan Liang kan.liang@linux.intel.com
commit 88ec7eedbbd21cad38707620ad6c48a4e9a87c18 upstream.
Perf doesn't work at low frequencies:
$ 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 frequency mode.
Fixes: c46e665f0377 ("perf/x86: Add INST_RETIRED.ALL workarounds") Signed-off-by: Kan Liang kan.liang@linux.intel.com Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Ravi Bangoria ravi.bangoria@amd.com Cc: Peter Zijlstra peterz@infradead.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250117151913.3043942-1-kan.liang@linux.intel.com Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@amd.com/ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -623,7 +623,7 @@ int x86_pmu_hw_config(struct perf_event if (event->attr.type == event->pmu->type) event->hw.config |= event->attr.config & X86_RAW_EVENT_MASK;
- 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)