[kvm-unit-tests Patch v4 06/17] x86: pmu: Add asserts to warn inconsistent fixed events and counters

Dapeng Mi
2024-04-19T03:45:51Z

Current PMU code deosn't check whether PMU fixed counter number is
larger than pre-defined fixed events. If so, it would cause memory
access out of range.

So add assert to warn this invalid case.

Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
x86/pmu.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/x86/pmu.c b/x86/pmu.c
index 494af4012e84..461a4090d475 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -111,8 +111,12 @@ static struct pmu_event* get_counter_event(pmu_counter_t *cnt)
for (i = 0; i < gp_events_size; i++)
if (gp_events[i].unit_sel == (cnt->config & 0xffff))
return &gp_events[i];
- } else
- return &fixed_events[cnt->ctr - MSR_CORE_PERF_FIXED_CTR0];
+ } else {
+ unsigned int idx = cnt->ctr - MSR_CORE_PERF_FIXED_CTR0;
+
+ assert(idx < ARRAY_SIZE(fixed_events));
+ return &fixed_events[idx];
+ }

return (void*)0;
}
@@ -738,6 +742,8 @@ int main(int ac, char **av)
printf("Fixed counters: %d\n", pmu.nr_fixed_counters);
printf("Fixed counter width: %d\n", pmu.fixed_counter_width);

+ assert(pmu.nr_fixed_counters <= ARRAY_SIZE(fixed_events));
+
apic_write(APIC_LVTPC, PMI_VECTOR);

check_counters();
--
2.34.1