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// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
void test_stacktrace_build_id(void)
{
int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
const char *file = "./test_stacktrace_build_id.o";
int bytes, efd, err, pmu_fd, prog_fd, stack_trace_len;
struct perf_event_attr attr = {};
__u32 key, previous_key, val, duration = 0;
struct bpf_object *obj;
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;
retry:
err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
goto out;
/* Get the ID for the sched/sched_switch tracepoint */
snprintf(buf, sizeof(buf),
"/sys/kernel/debug/tracing/events/random/urandom_read/id");
efd = open(buf, O_RDONLY, 0);
if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
goto close_prog;
bytes = read(efd, buf, sizeof(buf));
close(efd);
if (CHECK(bytes <= 0 || bytes >= sizeof(buf),
"read", "bytes %d errno %d\n", bytes, errno))
goto close_prog;
/* Open the perf event and attach bpf progrram */
attr.config = strtol(buf, NULL, 0);
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
attr.sample_period = 1;
attr.wakeup_events = 1;
pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
0 /* cpu 0 */, -1 /* group id */,
0 /* flags */);
if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
pmu_fd, errno))
goto close_prog;
err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
err, errno))
goto close_pmu;
err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
err, errno))
goto disable_pmu;
/* find map fds */
control_map_fd = bpf_find_map(__func__, obj, "control_map");
if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
err, errno))
goto disable_pmu;
stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap");
if (CHECK(stack_amap_fd < 0, "bpf_find_map stack_amap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")
== 0);
assert(system("./urandom_read") == 0);
/* 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 disable_pmu;
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 disable_pmu;
err = extract_build_id(buf, 256);
if (CHECK(err, "get build_id with readelf",
"err %d errno %d\n", err, errno))
goto disable_pmu;
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 disable_pmu;
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 disable_pmu;
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--) {
ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
close(pmu_fd);
bpf_object__close(obj);
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 disable_pmu;
stack_trace_len = PERF_MAX_STACK_DEPTH
* sizeof(struct bpf_stack_build_id);
err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
"err %d errno %d\n", err, errno);
disable_pmu:
ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
close_pmu:
close(pmu_fd);
close_prog:
bpf_object__close(obj);
out:
return;
}
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