bpf/prog_tests/stacktrace_build_id.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <test_progs.h>
0003 #include "test_stacktrace_build_id.skel.h"
0004
0005 void test_stacktrace_build_id(void)
0006 {
0007
0008     int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
0009     struct test_stacktrace_build_id *skel;
0010     int err, stack_trace_len;
0011     __u32 key, prev_key, val, duration = 0;
0012     char buf[256];
0013     int i, j;
0014     struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
0015     int build_id_matches = 0;
0016     int retry = 1;
0017
0018 retry:
0019     skel = test_stacktrace_build_id__open_and_load();
0020     if (CHECK(!skel, "skel_open_and_load", "skeleton open/load failed\n"))
0021         return;
0022
0023     err = test_stacktrace_build_id__attach(skel);
0024     if (CHECK(err, "attach_tp", "err %d\n", err))
0025         goto cleanup;
0026
0027     /* find map fds */
0028     control_map_fd = bpf_map__fd(skel->maps.control_map);
0029     stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
0030     stackmap_fd = bpf_map__fd(skel->maps.stackmap);
0031     stack_amap_fd = bpf_map__fd(skel->maps.stack_amap);
0032
0033     if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
0034         goto cleanup;
0035     if (CHECK_FAIL(system("./urandom_read")))
0036         goto cleanup;
0037     /* disable stack trace collection */
0038     key = 0;
0039     val = 1;
0040     bpf_map_update_elem(control_map_fd, &key, &val, 0);
0041
0042     /* for every element in stackid_hmap, we can find a corresponding one
0043      * in stackmap, and vise versa.
0044      */
0045     err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
0046     if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
0047           "err %d errno %d\n", err, errno))
0048         goto cleanup;
0049
0050     err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
0051     if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
0052           "err %d errno %d\n", err, errno))
0053         goto cleanup;
0054
0055     err = extract_build_id(buf, 256);
0056
0057     if (CHECK(err, "get build_id with readelf",
0058           "err %d errno %d\n", err, errno))
0059         goto cleanup;
0060
0061     err = bpf_map__get_next_key(skel->maps.stackmap, NULL, &key, sizeof(key));
0062     if (CHECK(err, "get_next_key from stackmap",
0063           "err %d, errno %d\n", err, errno))
0064         goto cleanup;
0065
0066     do {
0067         char build_id[64];
0068
0069         err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
0070         if (CHECK(err, "lookup_elem from stackmap",
0071               "err %d, errno %d\n", err, errno))
0072             goto cleanup;
0073         for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
0074             if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
0075                 id_offs[i].offset != 0) {
0076                 for (j = 0; j < 20; ++j)
0077                     sprintf(build_id + 2 * j, "%02x",
0078                         id_offs[i].build_id[j] & 0xff);
0079                 if (strstr(buf, build_id) != NULL)
0080                     build_id_matches = 1;
0081             }
0082         prev_key = key;
0083     } while (bpf_map__get_next_key(skel->maps.stackmap, &prev_key, &key, sizeof(key)) == 0);
0084
0085     /* stack_map_get_build_id_offset() is racy and sometimes can return
0086      * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
0087      * try it one more time.
0088      */
0089     if (build_id_matches < 1 && retry--) {
0090         test_stacktrace_build_id__destroy(skel);
0091         printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
0092                __func__);
0093         goto retry;
0094     }
0095
0096     if (CHECK(build_id_matches < 1, "build id match",
0097           "Didn't find expected build ID from the map\n"))
0098         goto cleanup;
0099
0100     stack_trace_len = PERF_MAX_STACK_DEPTH *
0101               sizeof(struct bpf_stack_build_id);
0102     err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
0103     CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
0104           "err %d errno %d\n", err, errno);
0105
0106 cleanup:
0107     test_stacktrace_build_id__destroy(skel);
0108 }