1// SPDX-License-Identifier: GPL-2.0
  2#include <test_progs.h>
  3
  4void test_stacktrace_build_id(void)
  5{
  6	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
  7	const char *prog_name = "tracepoint/random/urandom_read";
  8	const char *file = "./test_stacktrace_build_id.o";
  9	int err, prog_fd, stack_trace_len;
 10	__u32 key, previous_key, val, duration = 0;
 11	struct bpf_program *prog;
 12	struct bpf_object *obj;
 13	struct bpf_link *link = NULL;
 14	char buf[256];
 15	int i, j;
 16	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
 17	int build_id_matches = 0;
 18	int retry = 1;
 19
 20retry:
 21	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
 22	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
 23		return;
 24
 25	prog = bpf_object__find_program_by_title(obj, prog_name);
 26	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
 27		goto close_prog;
 28
 29	link = bpf_program__attach_tracepoint(prog, "random", "urandom_read");
 30	if (CHECK(IS_ERR(link), "attach_tp", "err %ld\n", PTR_ERR(link)))
 31		goto close_prog;
 32
 33	/* find map fds */
 34	control_map_fd = bpf_find_map(__func__, obj, "control_map");
 35	if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
 36		  "err %d errno %d\n", err, errno))
 37		goto disable_pmu;
 38
 39	stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
 40	if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
 41		  "err %d errno %d\n", err, errno))
 42		goto disable_pmu;
 43
 44	stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
 45	if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
 46		  err, errno))
 47		goto disable_pmu;
 48
 49	stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap");
 50	if (CHECK(stack_amap_fd < 0, "bpf_find_map stack_amap",
 51		  "err %d errno %d\n", err, errno))
 52		goto disable_pmu;
 53
 54	if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
 55		goto disable_pmu;
 56	if (CHECK_FAIL(system("./urandom_read")))
 57		goto disable_pmu;
 58	/* disable stack trace collection */
 59	key = 0;
 60	val = 1;
 61	bpf_map_update_elem(control_map_fd, &key, &val, 0);
 62
 63	/* for every element in stackid_hmap, we can find a corresponding one
 64	 * in stackmap, and vise versa.
 65	 */
 66	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
 67	if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
 68		  "err %d errno %d\n", err, errno))
 69		goto disable_pmu;
 70
 71	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
 72	if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
 73		  "err %d errno %d\n", err, errno))
 74		goto disable_pmu;
 75
 76	err = extract_build_id(buf, 256);
 77
 78	if (CHECK(err, "get build_id with readelf",
 79		  "err %d errno %d\n", err, errno))
 80		goto disable_pmu;
 81
 82	err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
 83	if (CHECK(err, "get_next_key from stackmap",
 84		  "err %d, errno %d\n", err, errno))
 85		goto disable_pmu;
 86
 87	do {
 88		char build_id[64];
 89
 90		err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
 91		if (CHECK(err, "lookup_elem from stackmap",
 92			  "err %d, errno %d\n", err, errno))
 93			goto disable_pmu;
 94		for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
 95			if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
 96			    id_offs[i].offset != 0) {
 97				for (j = 0; j < 20; ++j)
 98					sprintf(build_id + 2 * j, "%02x",
 99						id_offs[i].build_id[j] & 0xff);
100				if (strstr(buf, build_id) != NULL)
101					build_id_matches = 1;
102			}
103		previous_key = key;
104	} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
105
106	/* stack_map_get_build_id_offset() is racy and sometimes can return
107	 * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
108	 * try it one more time.
109	 */
110	if (build_id_matches < 1 && retry--) {
111		bpf_link__destroy(link);
112		bpf_object__close(obj);
113		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
114		       __func__);
115		goto retry;
116	}
117
118	if (CHECK(build_id_matches < 1, "build id match",
119		  "Didn't find expected build ID from the map\n"))
120		goto disable_pmu;
121
122	stack_trace_len = PERF_MAX_STACK_DEPTH
123		* sizeof(struct bpf_stack_build_id);
124	err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
125	CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
126	      "err %d errno %d\n", err, errno);
127
128disable_pmu:
129	bpf_link__destroy(link);
130
131close_prog:
132	bpf_object__close(obj);
133}