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Commit 35578d79 authored by Kaixu Xia's avatar Kaixu Xia Committed by David S. Miller
Browse files

bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter 



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: default avatarKaixu Xia <xiakaixu@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ea317b26

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -271,6 +271,7 @@ enum bpf_func_id { 
	 */

	BPF_FUNC_skb_get_tunnel_key,

	BPF_FUNC_skb_set_tunnel_key,

	BPF_FUNC_perf_event_read,	/* u64 bpf_perf_event_read(&map, index) */

	__BPF_FUNC_MAX_ID,

};

kernel/bpf/verifier.c

+33 −15
Original line number Diff line number Diff line
@@ -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;
@@ -837,6 +845,28 @@ static int check_func_arg(struct verifier_env *env, u32 regno, 
	return err;

}



static int check_map_func_compatibility(struct bpf_map *map, int func_id)

{

	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;
@@ -912,21 +942,9 @@ 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_map_func_compatibility(map, func_id);

	if (err)

		return err;



	return 0;

}

kernel/trace/bpf_trace.c

+31 −0
Original line number Diff line number Diff line
@@ -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_local(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;

	}