Commit 020a32d9 authored by Yonghong Song's avatar Yonghong Song Committed by David S. Miller
Browse files

bpf: add a test case for helper bpf_perf_event_read_value 



The bpf sample program tracex6 is enhanced to use the new
helper to read enabled/running time as well.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarAlexei Starovoitov <ast@fb.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 908432ca

samples/bpf/tracex6_kern.c

+26 −0
Original line number Diff line number Diff line
@@ -15,6 +15,12 @@ struct bpf_map_def SEC("maps") values = { 
	.value_size = sizeof(u64),

	.max_entries = 64,

};

struct bpf_map_def SEC("maps") values2 = {

	.type = BPF_MAP_TYPE_HASH,

	.key_size = sizeof(int),

	.value_size = sizeof(struct bpf_perf_event_value),

	.max_entries = 64,

};



SEC("kprobe/htab_map_get_next_key")

int bpf_prog1(struct pt_regs *ctx)
@@ -37,5 +43,25 @@ int bpf_prog1(struct pt_regs *ctx) 
	return 0;

}



SEC("kprobe/htab_map_lookup_elem")

int bpf_prog2(struct pt_regs *ctx)

{

	u32 key = bpf_get_smp_processor_id();

	struct bpf_perf_event_value *val, buf;

	int error;



	error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf));

	if (error)

		return 0;



	val = bpf_map_lookup_elem(&values2, &key);

	if (val)

		*val = buf;

	else

		bpf_map_update_elem(&values2, &key, &buf, BPF_NOEXIST);



	return 0;

}



char _license[] SEC("license") = "GPL";

u32 _version SEC("version") = LINUX_VERSION_CODE;

samples/bpf/tracex6_user.c

+12 −1
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 


static void check_on_cpu(int cpu, struct perf_event_attr *attr)

{

	struct bpf_perf_event_value value2;

	int pmu_fd, error = 0;

	cpu_set_t set;

	__u64 value;
@@ -46,8 +47,18 @@ static void check_on_cpu(int cpu, struct perf_event_attr *attr) 
		fprintf(stderr, "Value missing for CPU %d\n", cpu);

		error = 1;

		goto on_exit;

	}

	} else {

		fprintf(stderr, "CPU %d: %llu\n", cpu, value);

	}

	/* The above bpf_map_lookup_elem should trigger the second kprobe */

	if (bpf_map_lookup_elem(map_fd[2], &cpu, &value2)) {

		fprintf(stderr, "Value2 missing for CPU %d\n", cpu);

		error = 1;

		goto on_exit;

	} else {

		fprintf(stderr, "CPU %d: counter: %llu, enabled: %llu, running: %llu\n", cpu,

			value2.counter, value2.enabled, value2.running);

	}



on_exit:

	assert(bpf_map_delete_elem(map_fd[0], &cpu) == 0 || error);

tools/include/uapi/linux/bpf.h

+2 −1
Original line number Diff line number Diff line
@@ -697,7 +697,8 @@ union bpf_attr { 
	FN(redirect_map),		\

	FN(sk_redirect_map),		\

	FN(sock_map_update),		\

	FN(xdp_adjust_meta),

	FN(xdp_adjust_meta),		\

	FN(perf_event_read_value),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

tools/testing/selftests/bpf/bpf_helpers.h

+3 −0
Original line number Diff line number Diff line
@@ -72,6 +72,9 @@ static int (*bpf_sk_redirect_map)(void *map, int key, int flags) = 
static int (*bpf_sock_map_update)(void *map, void *key, void *value,

				  unsigned long long flags) =

	(void *) BPF_FUNC_sock_map_update;

static int (*bpf_perf_event_read_value)(void *map, unsigned long long flags,

					void *buf, unsigned int buf_size) =

	(void *) BPF_FUNC_perf_event_read_value;





/* llvm builtin functions that eBPF C program may use to