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

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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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Kaixu Xia 2015-08-06 07:02:35 +00:00 • committed by David S. Miller
commit 35578d7984
4 changed files with 66 additions and 15 deletions
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48
kernel/bpf/verifier.c
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@ -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;
}