This patch includes two fixes for SB:
* the 3rd fixed counter ("ref cpu cycles") can sometimes report
less than the number of iterations
* there is an 8th counter which causes out of bounds accesses
to gp_event or check_counters_many's cnt array
There is still a bug in KVM, because the "pmu all counters-0"
test fails. (It passes if you use any 6 of the 8 gp counters,
fails if you use 7 or 8).
---
x86/pmu.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/x86/pmu.c b/x86/pmu.c
index 2c46f31..dca753a 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -88,9 +88,10 @@ struct pmu_event {
}, fixed_events[] = {
{"fixed 1", MSR_CORE_PERF_FIXED_CTR0, 10*N, 10.2*N},
{"fixed 2", MSR_CORE_PERF_FIXED_CTR0 + 1, 1*N, 30*N},
- {"fixed 3", MSR_CORE_PERF_FIXED_CTR0 + 2, 1*N, 30*N}
+ {"fixed 3", MSR_CORE_PERF_FIXED_CTR0 + 2, 0.1*N, 30*N}
};
+static int num_counters;
static int tests, failures;
char *buf;
@@ -237,7 +238,7 @@ static void check_gp_counter(struct pmu_event *evt)
};
int i;
- for (i = 0; i < eax.split.num_counters; i++, cnt.ctr++) {
+ for (i = 0; i < num_counters; i++, cnt.ctr++) {
cnt.count = 0;
measure(&cnt, 1);
report(evt->name, i, verify_event(cnt.count, evt));
@@ -276,7 +277,7 @@ static void check_counters_many(void)
pmu_counter_t cnt[10];
int i, n;
- for (i = 0, n = 0; n < eax.split.num_counters; i++) {
+ for (i = 0, n = 0; n < num_counters; i++) {
if (ebx.full & (1 << i))
continue;
@@ -316,10 +317,10 @@ static void check_counter_overflow(void)
/* clear status before test */
wrmsr(MSR_CORE_PERF_GLOBAL_OVF_CTRL, rdmsr(MSR_CORE_PERF_GLOBAL_STATUS));
- for (i = 0; i < eax.split.num_counters + 1; i++, cnt.ctr++) {
+ for (i = 0; i < num_counters + 1; i++, cnt.ctr++) {
uint64_t status;
int idx;
- if (i == eax.split.num_counters)
+ if (i == num_counters)
cnt.ctr = fixed_events[0].unit_sel;
if (i % 2)
cnt.config |= EVNTSEL_INT;
@@ -355,7 +356,7 @@ static void check_rdpmc(void)
uint64_t val = 0x1f3456789ull;
int i;
- for (i = 0; i < eax.split.num_counters; i++) {
+ for (i = 0; i < num_counters; i++) {
uint64_t x = (val & 0xffffffff) |
((1ull << (eax.split.bit_width - 32)) - 1) << 32;
wrmsr(MSR_IA32_PERFCTR0 + i, val);
@@ -395,6 +396,14 @@ int main(int ac, char **av)
printf("Fixed counters: %d\n", edx.split.num_counters_fixed);
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);
+ while (id.b) {
+ num_counters--;
+ id.b &= id.b - 1;
+ }
+
apic_write(APIC_LVTPC, PC_VECTOR);
check_gp_counters();
--
1.8.2.1
--
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