1/*
  2 * Test backward bit in event attribute, read ring buffer from end to
  3 * beginning
  4 */
  5
  6#include <perf.h>
  7#include <evlist.h>
  8#include <sys/prctl.h>
  9#include "tests.h"
 10#include "debug.h"
 11
 12#define NR_ITERS 111
 13
 14static void testcase(void)
 15{
 16	int i;
 17
 18	for (i = 0; i < NR_ITERS; i++) {
 19		char proc_name[10];
 20
 21		snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
 22		prctl(PR_SET_NAME, proc_name);
 23	}
 24}
 25
 26static int count_samples(struct perf_evlist *evlist, int *sample_count,
 27			 int *comm_count)
 28{
 29	int i;
 30
 31	for (i = 0; i < evlist->nr_mmaps; i++) {
 32		union perf_event *event;
 33
 34		perf_mmap__read_catchup(&evlist->backward_mmap[i]);
 35		while ((event = perf_mmap__read_backward(&evlist->backward_mmap[i])) != NULL) {
 36			const u32 type = event->header.type;
 37
 38			switch (type) {
 39			case PERF_RECORD_SAMPLE:
 40				(*sample_count)++;
 41				break;
 42			case PERF_RECORD_COMM:
 43				(*comm_count)++;
 44				break;
 45			default:
 46				pr_err("Unexpected record of type %d\n", type);
 47				return TEST_FAIL;
 48			}
 49		}
 50	}
 51	return TEST_OK;
 52}
 53
 54static int do_test(struct perf_evlist *evlist, int mmap_pages,
 55		   int *sample_count, int *comm_count)
 56{
 57	int err;
 58	char sbuf[STRERR_BUFSIZE];
 59
 60	err = perf_evlist__mmap(evlist, mmap_pages, true);
 61	if (err < 0) {
 62		pr_debug("perf_evlist__mmap: %s\n",
 63			 str_error_r(errno, sbuf, sizeof(sbuf)));
 64		return TEST_FAIL;
 65	}
 66
 67	perf_evlist__enable(evlist);
 68	testcase();
 69	perf_evlist__disable(evlist);
 70
 71	err = count_samples(evlist, sample_count, comm_count);
 72	perf_evlist__munmap(evlist);
 73	return err;
 74}
 75
 76
 77int test__backward_ring_buffer(int subtest __maybe_unused)
 78{
 79	int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0;
 80	char pid[16], sbuf[STRERR_BUFSIZE];
 81	struct perf_evlist *evlist;
 82	struct perf_evsel *evsel __maybe_unused;
 83	struct parse_events_error parse_error;
 84	struct record_opts opts = {
 85		.target = {
 86			.uid = UINT_MAX,
 87			.uses_mmap = true,
 88		},
 89		.freq	      = 0,
 90		.mmap_pages   = 256,
 91		.default_interval = 1,
 92	};
 93
 94	snprintf(pid, sizeof(pid), "%d", getpid());
 95	pid[sizeof(pid) - 1] = '\0';
 96	opts.target.tid = opts.target.pid = pid;
 97
 98	evlist = perf_evlist__new();
 99	if (!evlist) {
100		pr_debug("Not enough memory to create evlist\n");
101		return TEST_FAIL;
102	}
103
104	err = perf_evlist__create_maps(evlist, &opts.target);
105	if (err < 0) {
106		pr_debug("Not enough memory to create thread/cpu maps\n");
107		goto out_delete_evlist;
108	}
109
110	bzero(&parse_error, sizeof(parse_error));
111	/*
112	 * Set backward bit, ring buffer should be writing from end. Record
113	 * it in aux evlist
114	 */
115	err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);
116	if (err) {
117		pr_debug("Failed to parse tracepoint event, try use root\n");
118		ret = TEST_SKIP;
119		goto out_delete_evlist;
120	}
121
122	perf_evlist__config(evlist, &opts, NULL);
123
124	err = perf_evlist__open(evlist);
125	if (err < 0) {
126		pr_debug("perf_evlist__open: %s\n",
127			 str_error_r(errno, sbuf, sizeof(sbuf)));
128		goto out_delete_evlist;
129	}
130
131	ret = TEST_FAIL;
132	err = do_test(evlist, opts.mmap_pages, &sample_count,
133		      &comm_count);
134	if (err != TEST_OK)
135		goto out_delete_evlist;
136
137	if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
138		pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
139		       sample_count, comm_count);
140		goto out_delete_evlist;
141	}
142
143	err = do_test(evlist, 1, &sample_count, &comm_count);
144	if (err != TEST_OK)
145		goto out_delete_evlist;
146
147	ret = TEST_OK;
148out_delete_evlist:
149	perf_evlist__delete(evlist);
150	return ret;
151}