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 | 12 +++++++++-
include/uapi/linux/bpf.h | 1 +
kernel/bpf/verifier.c | 56 +++++++++++++++++++++++++++++++++-------------
kernel/events/core.c | 10 +--------
kernel/trace/bpf_trace.c | 37 ++++++++++++++++++++++++++++++
6 files changed, 92 insertions(+), 25 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d0b394a..db9f781 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 27e05c1..c1a3f39 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -662,7 +662,7 @@ 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);
struct perf_sample_data {
/*
@@ -863,6 +863,14 @@ static inline u64 __perf_event_count(struct perf_event
*event)
return local64_read(&event->count) + atomic64_read(&event->child_count);
}
+static inline u64 perf_event_count(struct perf_event *event)
+{
+ if (event->pmu->count)
+ return event->pmu->count(event);
+
+ return __perf_event_count(event);
+}
+
extern void perf_event_mmap(struct vm_area_struct *vma);
extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks
*callbacks);
@@ -984,6 +992,8 @@ static struct perf_event *perf_event_get(unsigned int fd)
{ return ERR_PTR(-EIN
static inline void perf_event_print_debug(void)
{ }
static inline int perf_event_task_disable(void)
{ return -EINVAL; }
static inline int perf_event_task_enable(void) {
return -EINVAL; }
+static inline void __perf_event_read(void *info) { }
+static inline u64 perf_event_count(struct perf_event *event) {
return 0; }
static inline int perf_event_refresh(struct perf_event *event, int refresh)
{
return -EINVAL;
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/verifier.c b/kernel/bpf/verifier.c
index 039d866..93b6624 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -833,6 +833,44 @@ static int check_func_arg(struct verifier_env *env, u32
regno,
return err;
}
+static int check_func_limit(struct bpf_map **mapp, int func_id)
+{
+ struct bpf_map *map = *mapp;
+
+ if (map && map->map_type == BPF_MAP_TYPE_PROG_ARRAY &&
+ func_id != BPF_FUNC_tail_call)
+ /* prog_array map type needs extra care:
+ * only allow to pass it into bpf_tail_call() for now.
+ * bpf_map_delete_elem() can be allowed in the future,
+ * while bpf_map_update_elem() must only be done via syscall
+ */
+ return -EINVAL;
+
+ if (func_id == BPF_FUNC_tail_call &&
+ map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
+ /* don't allow any other map type to be passed into
+ * bpf_tail_call()
+ */
+ return -EINVAL;
+
+ if (map && map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+ func_id != BPF_FUNC_perf_event_read)
+ /* perf_event_array map type needs extra care:
+ * only allow to pass it into bpf_perf_event_read() for now.
+ * bpf_map_update/delete_elem() must only be done via syscall
+ */
+ return -EINVAL;
+
+ if (func_id == BPF_FUNC_perf_event_read &&
+ map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
+ /* don't allow any other map type to be passed into
+ * bpf_perf_event_read()
+ */
+ return -EINVAL;
+
+ return 0;
+}
+
static int check_call(struct verifier_env *env, int func_id)
{
struct verifier_state *state = &env->cur_state;
@@ -908,21 +946,9 @@ static int check_call(struct verifier_env *env, int
func_id)
return -EINVAL;
}
- if (map && map->map_type == BPF_MAP_TYPE_PROG_ARRAY &&
- func_id != BPF_FUNC_tail_call)
- /* prog_array map type needs extra care:
- * only allow to pass it into bpf_tail_call() for now.
- * bpf_map_delete_elem() can be allowed in the future,
- * while bpf_map_update_elem() must only be done via syscall
- */
- return -EINVAL;
-
- if (func_id == BPF_FUNC_tail_call &&
- map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
- /* don't allow any other map type to be passed into
- * bpf_tail_call()
- */
- return -EINVAL;
+ err = check_func_limit(&map, func_id);
+ if (err)
+ return err;
return 0;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 58f0d47..1e4d65a 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)
{
struct perf_event *event = info;
struct perf_event_context *ctx = event->ctx;
@@ -3204,14 +3204,6 @@ static void __perf_event_read(void *info)
raw_spin_unlock(&ctx->lock);
}
-static inline u64 perf_event_count(struct perf_event *event)
-{
- if (event->pmu->count)
- return event->pmu->count(event);
-
- return __perf_event_count(event);
-}
-
static u64 perf_event_read(struct perf_event *event)
{
/*
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041a..5b81da1 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -158,6 +158,41 @@ const struct bpf_func_proto
*bpf_get_trace_printk_proto(void)
return &bpf_trace_printk_proto;
}
+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 (unlikely(index >= array->map.max_entries))
+ return -E2BIG;
+
+ event = (struct perf_event *)array->ptrs[index];
+ if (!event)
+ return -ENOENT;
+
+ if (unlikely(event->state != PERF_EVENT_STATE_ACTIVE))
+ return -EINVAL;
+
+ if (event->oncpu != raw_smp_processor_id() &&
+ event->ctx->task != current)
+ return -EINVAL;
+
+ if (unlikely(event->attr.inherit))
+ return -EINVAL;
+
+ __perf_event_read(event);
+ return perf_event_count(event);
+}
+
+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,
+};
+
static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id
func_id)
{
switch (func_id) {
@@ -183,6 +218,8 @@ static const struct bpf_func_proto
*kprobe_prog_func_proto(enum bpf_func_id func
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;
}
--
1.8.3.4
--
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