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// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include "test_stacktrace_build_id.skel.h"
static __u64 read_perf_max_sample_freq(void)
{
__u64 sample_freq = 5000; /* fallback to 5000 on error */
FILE *f;
f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r");
if (f == NULL)
return sample_freq;
fscanf(f, "%llu", &sample_freq);
fclose(f);
return sample_freq;
}
void test_stacktrace_build_id_nmi(void)
{
int control_map_fd, stackid_hmap_fd, stackmap_fd;
struct test_stacktrace_build_id *skel;
int err, pmu_fd;
struct perf_event_attr attr = {
.freq = 1,
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
};
__u32 key, previous_key, val, duration = 0;
char buf[256];
int i, j;
struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
int build_id_matches = 0;
int retry = 1;
attr.sample_freq = read_perf_max_sample_freq();
retry:
skel = test_stacktrace_build_id__open();
if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
return;
/* override program type */
bpf_program__set_perf_event(skel->progs.oncpu);
err = test_stacktrace_build_id__load(skel);
if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
goto cleanup;
pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
0 /* cpu 0 */, -1 /* group id */,
0 /* flags */);
if (pmu_fd < 0 && errno == ENOENT) {
printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
test__skip();
goto cleanup;
}
if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
pmu_fd, errno))
goto cleanup;
skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
pmu_fd);
if (CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event",
"err %ld\n", PTR_ERR(skel->links.oncpu))) {
close(pmu_fd);
goto cleanup;
}
/* find map fds */
control_map_fd = bpf_map__fd(skel->maps.control_map);
stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
stackmap_fd = bpf_map__fd(skel->maps.stackmap);
if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
goto cleanup;
if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000")))
goto cleanup;
/* disable stack trace collection */
key = 0;
val = 1;
bpf_map_update_elem(control_map_fd, &key, &val, 0);
/* for every element in stackid_hmap, we can find a corresponding one
* in stackmap, and vise versa.
*/
err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
"err %d errno %d\n", err, errno))
goto cleanup;
err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
"err %d errno %d\n", err, errno))
goto cleanup;
err = extract_build_id(buf, 256);
if (CHECK(err, "get build_id with readelf",
"err %d errno %d\n", err, errno))
goto cleanup;
err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
if (CHECK(err, "get_next_key from stackmap",
"err %d, errno %d\n", err, errno))
goto cleanup;
do {
char build_id[64];
err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
if (CHECK(err, "lookup_elem from stackmap",
"err %d, errno %d\n", err, errno))
goto cleanup;
for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
id_offs[i].offset != 0) {
for (j = 0; j < 20; ++j)
sprintf(build_id + 2 * j, "%02x",
id_offs[i].build_id[j] & 0xff);
if (strstr(buf, build_id) != NULL)
build_id_matches = 1;
}
previous_key = key;
} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
/* stack_map_get_build_id_offset() is racy and sometimes can return
* BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
* try it one more time.
*/
if (build_id_matches < 1 && retry--) {
test_stacktrace_build_id__destroy(skel);
printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
__func__);
goto retry;
}
if (CHECK(build_id_matches < 1, "build id match",
"Didn't find expected build ID from the map\n"))
goto cleanup;
/*
* We intentionally skip compare_stack_ips(). This is because we
* only support one in_nmi() ips-to-build_id translation per cpu
* at any time, thus stack_amap here will always fallback to
* BPF_STACK_BUILD_ID_IP;
*/
cleanup:
test_stacktrace_build_id__destroy(skel);
}
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