1// SPDX-License-Identifier: GPL-2.0
  2#include <test_progs.h>
  3#include "test_stacktrace_build_id.skel.h"
  4
  5static __u64 read_perf_max_sample_freq(void)
  6{
  7	__u64 sample_freq = 5000; /* fallback to 5000 on error */
  8	FILE *f;
  9	__u32 duration = 0;
 10
 11	f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r");
 12	if (f == NULL)
 13		return sample_freq;
 14	CHECK(fscanf(f, "%llu", &sample_freq) != 1, "Get max sample rate",
 15		  "return default value: 5000,err %d\n", -errno);
 16	fclose(f);
 17	return sample_freq;
 18}
 19
 20void test_stacktrace_build_id_nmi(void)
 21{
 22	int control_map_fd, stackid_hmap_fd, stackmap_fd;
 23	struct test_stacktrace_build_id *skel;
 24	int err, pmu_fd;
 25	struct perf_event_attr attr = {
 26		.freq = 1,
 27		.type = PERF_TYPE_HARDWARE,
 28		.config = PERF_COUNT_HW_CPU_CYCLES,
 29	};
 30	__u32 key, previous_key, val, duration = 0;
 31	char buf[256];
 32	int i, j;
 33	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
 34	int build_id_matches = 0;
 35	int retry = 1;
 36
 37	attr.sample_freq = read_perf_max_sample_freq();
 38
 39retry:
 40	skel = test_stacktrace_build_id__open();
 41	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
 42		return;
 43
 44	/* override program type */
 45	bpf_program__set_perf_event(skel->progs.oncpu);
 46
 47	err = test_stacktrace_build_id__load(skel);
 48	if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
 49		goto cleanup;
 50
 51	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
 52			 0 /* cpu 0 */, -1 /* group id */,
 53			 0 /* flags */);
 54	if (pmu_fd < 0 && errno == ENOENT) {
 55		printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
 56		test__skip();
 57		goto cleanup;
 58	}
 59	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
 60		  pmu_fd, errno))
 61		goto cleanup;
 62
 63	skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
 64							   pmu_fd);
 65	if (!ASSERT_OK_PTR(skel->links.oncpu, "attach_perf_event")) {
 66		close(pmu_fd);
 67		goto cleanup;
 68	}
 69
 70	/* find map fds */
 71	control_map_fd = bpf_map__fd(skel->maps.control_map);
 72	stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
 73	stackmap_fd = bpf_map__fd(skel->maps.stackmap);
 74
 75	if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
 76		goto cleanup;
 77	if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000")))
 78		goto cleanup;
 79	/* disable stack trace collection */
 80	key = 0;
 81	val = 1;
 82	bpf_map_update_elem(control_map_fd, &key, &val, 0);
 83
 84	/* for every element in stackid_hmap, we can find a corresponding one
 85	 * in stackmap, and vise versa.
 86	 */
 87	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
 88	if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
 89		  "err %d errno %d\n", err, errno))
 90		goto cleanup;
 91
 92	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
 93	if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
 94		  "err %d errno %d\n", err, errno))
 95		goto cleanup;
 96
 97	err = extract_build_id(buf, 256);
 98
 99	if (CHECK(err, "get build_id with readelf",
100		  "err %d errno %d\n", err, errno))
101		goto cleanup;
102
103	err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
104	if (CHECK(err, "get_next_key from stackmap",
105		  "err %d, errno %d\n", err, errno))
106		goto cleanup;
107
108	do {
109		char build_id[64];
110
111		err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
112		if (CHECK(err, "lookup_elem from stackmap",
113			  "err %d, errno %d\n", err, errno))
114			goto cleanup;
115		for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
116			if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
117			    id_offs[i].offset != 0) {
118				for (j = 0; j < 20; ++j)
119					sprintf(build_id + 2 * j, "%02x",
120						id_offs[i].build_id[j] & 0xff);
121				if (strstr(buf, build_id) != NULL)
122					build_id_matches = 1;
123			}
124		previous_key = key;
125	} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
126
127	/* stack_map_get_build_id_offset() is racy and sometimes can return
128	 * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
129	 * try it one more time.
130	 */
131	if (build_id_matches < 1 && retry--) {
132		test_stacktrace_build_id__destroy(skel);
133		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
134		       __func__);
135		goto retry;
136	}
137
138	if (CHECK(build_id_matches < 1, "build id match",
139		  "Didn't find expected build ID from the map\n"))
140		goto cleanup;
141
142	/*
143	 * We intentionally skip compare_stack_ips(). This is because we
144	 * only support one in_nmi() ips-to-build_id translation per cpu
145	 * at any time, thus stack_amap here will always fallback to
146	 * BPF_STACK_BUILD_ID_IP;
147	 */
148
149cleanup:
150	test_stacktrace_build_id__destroy(skel);
151}