On 07/28/2015 01:17 PM, Kaixu Xia wrote:
According to the perf_event_map_fd and index, the function
bpf_perf_event_read() can convert the corresponding map
value to the pointer to struct perf_event and return the
Hardware PMU counter value.
Signed-off-by: Kaixu Xia <xiaka...@huawei.com>
---
include/linux/bpf.h | 1 +
include/linux/perf_event.h | 3 ++-
include/uapi/linux/bpf.h | 1 +
kernel/bpf/helpers.c | 36 ++++++++++++++++++++++++++++++++++++
kernel/events/core.c | 4 ++--
kernel/trace/bpf_trace.c | 2 ++
6 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3c9c0eb..516992c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -190,6 +190,7 @@ extern const struct bpf_func_proto
bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
extern const struct bpf_func_proto bpf_map_delete_elem_proto;
+extern const struct bpf_func_proto bpf_perf_event_read_proto;
extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
extern const struct bpf_func_proto bpf_tail_call_proto;
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2ea4067..899abcb 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -662,7 +662,8 @@ extern void perf_pmu_migrate_context(struct pmu *pmu,
int src_cpu, int dst_cpu);
extern u64 perf_event_read_value(struct perf_event *event,
u64 *enabled, u64 *running);
-
+extern void __perf_event_read(void *info);
+extern u64 perf_event_count(struct perf_event *event);
struct perf_sample_data {
/*
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 69a1f6b..b9b13ce 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -250,6 +250,7 @@ enum bpf_func_id {
* Return: 0 on success
*/
BPF_FUNC_get_current_comm,
+ BPF_FUNC_perf_event_read, /* u64 bpf_perf_event_read(&map, index)
*/
__BPF_FUNC_MAX_ID,
};
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1447ec0..c40c5ea 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -182,3 +182,39 @@ const struct bpf_func_proto bpf_get_current_comm_proto = {
.arg1_type = ARG_PTR_TO_STACK,
.arg2_type = ARG_CONST_STACK_SIZE,
};
+
+static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
+{
+ struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ struct perf_event *event;
+
+ if (index >= array->map.max_entries)
+ return -E2BIG;
Maybe unlikely(...), likewise below.
+ event = (struct perf_event *)array->ptrs[index];
+ if (!event)
+ return -ENOENT;
+
+ if (event->state != PERF_EVENT_STATE_ACTIVE)
+ return -EINVAL;
+
+ if (event->oncpu != raw_smp_processor_id() &&
+ event->ctx->task != current)
+ return -EINVAL;
+
+ if (event->attr.inherit)
+ return -EINVAL;
+
+ __perf_event_read(event);
+
+ return perf_event_count(event);
I believe this helper should rather go somewhere such as bpf_trace.c
(or under kernel/events/ ?), wouldn't we otherwise get a build error
when perf events are compiled out?
Anyway, I let perf folks comment on that (and the helper in general).
+}
+
+const struct bpf_func_proto bpf_perf_event_read_proto = {
+ .func = bpf_perf_event_read,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_ANYTHING,
+};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 58f0d47..c926c6d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3177,7 +3177,7 @@ void perf_event_exec(void)
/*
* Cross CPU call to read the hardware event
*/
-static void __perf_event_read(void *info)
+void __perf_event_read(void *info)
Does this need to be declared in a header file, no?
{
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;
@@ -3204,7 +3204,7 @@ static void __perf_event_read(void *info)
raw_spin_unlock(&ctx->lock);
}
-static inline u64 perf_event_count(struct perf_event *event)
+u64 perf_event_count(struct perf_event *event)
Likewise? Should the inlining be preserved?
{
if (event->pmu->count)
return event->pmu->count(event);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041a..9cf094f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -183,6 +183,8 @@ static const struct bpf_func_proto
*kprobe_prog_func_proto(enum bpf_func_id func
Btw, I'm wondering if the perf event map portions should actually better go
here into bpf_trace.c ...
return bpf_get_trace_printk_proto();
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
+ case BPF_FUNC_perf_event_read:
+ return &bpf_perf_event_read_proto;
default:
return NULL;
}
--
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