On 08/09/2017 22:13, Wei Huang wrote:
> Currently pmu.c sets num_counters to MIN(num_gp_counters, num_gp_events).
> This is to prevent the out-of-bound access to gp_events[] array in
> check_counters_many(). However it also means that check_counters_many()
> can NOT stress all gp counters if num_gp_counters > num_gp_events. This
> small patch changes the value of num_counters back to num_gp_counters and
> prevents the out-of-bound problem by using the mod function in the array
> access.
>
> Signed-off-by: Wei Huang <wei@xxxxxxxxxx>
> ---
> x86/pmu.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/x86/pmu.c b/x86/pmu.c
> index a0238dc..b56b61e 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -275,7 +275,8 @@ static void check_counters_many(void)
>
> cnt[n].count = 0;
> cnt[n].ctr = MSR_IA32_PERFCTR0 + n;
> - cnt[n].config = EVNTSEL_OS | EVNTSEL_USR | gp_events[i].unit_sel;
> + cnt[n].config = EVNTSEL_OS | EVNTSEL_USR |
> + gp_events[i % ARRAY_SIZE(gp_events)].unit_sel;
> n++;
> }
> for (i = 0; i < edx.split.num_counters_fixed; i++) {
> @@ -397,8 +398,6 @@ int main(int ac, char **av)
> printf("Fixed counter width: %d\n", edx.split.bit_width_fixed);
>
> num_counters = eax.split.num_counters;
> - if (num_counters > ARRAY_SIZE(gp_events))
> - num_counters = ARRAY_SIZE(gp_events);
>
> apic_write(APIC_LVTPC, PC_VECTOR);
>
>
Clever! I applied the patch.
Paolo
