On 2015/7/17 19:05, Peter Zijlstra wrote:
On Fri, Jul 17, 2015 at 06:43:35PM +0800, kaixu xia wrote:
The function bpf_read_pmu() can get the specific map key, convert
the corresponding map value to the pointer to struct perf_event and
return the Hardware PMU counter value.
Thanks for having me on Cc :/
Signed-off-by: kaixu xia <xiaka...@huawei.com>
---
+static u64 bpf_read_pmu(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ void *value = (void *) (unsigned long) r1;
+ struct perf_event *event;
+ u64 count;
+
+ if (!value || !(*(unsigned long *)value))
+ return 0;
+
+ event = (struct perf_event *)(*(unsigned long *)value);
+
+ if (event->state == PERF_EVENT_STATE_ACTIVE)
+ event->pmu->read(event);
+
+ count = local64_read(&event->count);
+
+ return count;
+}
Hell no, that's way broken.
What about calling perf_event_read_value() then?
...
struct perf_event_context *ctx;
u64 enabled, u64 running
ctx = perf_event_ctx_lock(event);
if (!event->state == PERF_EVENT_STATE_ERROR) {
count = perf_event_read_value(event, &enable, &running);
}
perf_event_ctx_unlock(event, ctx);
...
Code is from perf_read().
Thank you.
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