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 | 2 ++
include/uapi/linux/bpf.h | 1 +
kernel/bpf/verifier.c | 49 ++++++++++++++++++++++++++++++++--------------
kernel/events/core.c | 19 ++++++++++++++++++
kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++++
6 files changed, 88 insertions(+), 15 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 81fc99e..6f1e448 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -643,6 +643,7 @@ extern void perf_event_free_task(struct task_struct *task);
extern void perf_event_delayed_put(struct task_struct *task);
extern struct perf_event *perf_event_get(unsigned int fd);
extern struct perf_event_attr *perf_event_attrs(struct perf_event *event);
+extern u64 perf_event_read_internal(struct perf_event *event);
extern void perf_event_print_debug(void);
extern void perf_pmu_disable(struct pmu *pmu);
extern void perf_pmu_enable(struct pmu *pmu);
@@ -986,6 +987,7 @@ static inline struct perf_event_attr
*perf_event_attrs(struct perf_event *event)
{
return ERR_PTR(-EINVAL);
}
+static inline u64 perf_event_read_internal(struct perf_event *event) {
return -EINVAL; }
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; }
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..45fae14 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -238,6 +238,14 @@ static const char * const reg_type_str[] = {
[CONST_IMM] = "imm",
};
+static const struct {
+ int map_type;
+ int func_id;
+} func_limit[] = {
+ {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call},
+ {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read},
+};
+
static void print_verifier_state(struct verifier_env *env)
{
enum bpf_reg_type t;
@@ -833,6 +841,29 @@ 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;
+ bool bool_map, bool_func;
+ int i;
+
+ if (!map)
+ return 0;
+
+ for (i = 0; i <= ARRAY_SIZE(func_limit); i++) {
+ bool_map = (map->map_type == func_limit[i].map_type);
+ bool_func = (func_id == func_limit[i].func_id);
+ /* only when map & func pair match it can continue.
+ * don't allow any other map type to be passed into
+ * the special func;
+ */
+ if (bool_map != bool_func)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int check_call(struct verifier_env *env, int func_id)
{
struct verifier_state *state = &env->cur_state;
@@ -908,21 +939,9 @@ 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 6251b53..726ca1b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8599,6 +8599,25 @@ struct perf_event_attr *perf_event_attrs(struct
perf_event *event)
return &event->attr;
}
+u64 perf_event_read_internal(struct perf_event *event)
+{
+ if (!event)
+ return -EINVAL;
+
+ 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);
+}
+
/*
* inherit a event from parent task to child task:
*/
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 88a041a..7d7b724 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -158,6 +158,35 @@ 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;
+
+ /*
+ * we don't know if the function is run successfully by the
+ * return value. It can be judged in other places, such as
+ * eBPF programs.
+ */
+ return perf_event_read_internal(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 +212,8 @@ 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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