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bpf: add a test case for helper bpf_perf_event_read_value

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

Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yonghong Song 2017-10-05 09:19:21 -07:00 committed by David S. Miller
parent 908432ca84
commit 020a32d958
4 changed files with 43 additions and 2 deletions
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26
samples/bpf/tracex6_kern.c
View file

@ -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;

13
samples/bpf/tracex6_user.c
View file

@ -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);
}
fprintf(stderr, "CPU %d: %llu\n", cpu, value);
on_exit:
assert(bpf_map_delete_elem(map_fd[0], &cpu) == 0 || error);

3
tools/include/uapi/linux/bpf.h
View file

@ -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

3
tools/testing/selftests/bpf/bpf_helpers.h
View file

@ -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