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 #include <errno.h>
12 
13 #define NR_ITERS 111
14 
15 static void testcase(void)
16 {
17 	int i;
18 
19 	for (i = 0; i < NR_ITERS; i++) {
20 		char proc_name[10];
21 
22 		snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
23 		prctl(PR_SET_NAME, proc_name);
24 	}
25 }
26 
27 static int count_samples(struct perf_evlist *evlist, int *sample_count,
28 			 int *comm_count)
29 {
30 	int i;
31 
32 	for (i = 0; i < evlist->nr_mmaps; i++) {
33 		union perf_event *event;
34 
35 		perf_mmap__read_catchup(&evlist->backward_mmap[i]);
36 		while ((event = perf_mmap__read_backward(&evlist->backward_mmap[i])) != NULL) {
37 			const u32 type = event->header.type;
38 
39 			switch (type) {
40 			case PERF_RECORD_SAMPLE:
41 				(*sample_count)++;
42 				break;
43 			case PERF_RECORD_COMM:
44 				(*comm_count)++;
45 				break;
46 			default:
47 				pr_err("Unexpected record of type %d\n", type);
48 				return TEST_FAIL;
49 			}
50 		}
51 	}
52 	return TEST_OK;
53 }
54 
55 static int do_test(struct perf_evlist *evlist, int mmap_pages,
56 		   int *sample_count, int *comm_count)
57 {
58 	int err;
59 	char sbuf[STRERR_BUFSIZE];
60 
61 	err = perf_evlist__mmap(evlist, mmap_pages, true);
62 	if (err < 0) {
63 		pr_debug("perf_evlist__mmap: %s\n",
64 			 str_error_r(errno, sbuf, sizeof(sbuf)));
65 		return TEST_FAIL;
66 	}
67 
68 	perf_evlist__enable(evlist);
69 	testcase();
70 	perf_evlist__disable(evlist);
71 
72 	err = count_samples(evlist, sample_count, comm_count);
73 	perf_evlist__munmap(evlist);
74 	return err;
75 }
76 
77 
78 int test__backward_ring_buffer(struct test *test __maybe_unused, int subtest __maybe_unused)
79 {
80 	int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0;
81 	char pid[16], sbuf[STRERR_BUFSIZE];
82 	struct perf_evlist *evlist;
83 	struct perf_evsel *evsel __maybe_unused;
84 	struct parse_events_error parse_error;
85 	struct record_opts opts = {
86 		.target = {
87 			.uid = UINT_MAX,
88 			.uses_mmap = true,
89 		},
90 		.freq	      = 0,
91 		.mmap_pages   = 256,
92 		.default_interval = 1,
93 	};
94 
95 	snprintf(pid, sizeof(pid), "%d", getpid());
96 	pid[sizeof(pid) - 1] = '\0';
97 	opts.target.tid = opts.target.pid = pid;
98 
99 	evlist = perf_evlist__new();
100 	if (!evlist) {
101 		pr_debug("Not enough memory to create evlist\n");
102 		return TEST_FAIL;
103 	}
104 
105 	err = perf_evlist__create_maps(evlist, &opts.target);
106 	if (err < 0) {
107 		pr_debug("Not enough memory to create thread/cpu maps\n");
108 		goto out_delete_evlist;
109 	}
110 
111 	bzero(&parse_error, sizeof(parse_error));
112 	/*
113 	 * Set backward bit, ring buffer should be writing from end. Record
114 	 * it in aux evlist
115 	 */
116 	err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);
117 	if (err) {
118 		pr_debug("Failed to parse tracepoint event, try use root\n");
119 		ret = TEST_SKIP;
120 		goto out_delete_evlist;
121 	}
122 
123 	perf_evlist__config(evlist, &opts, NULL);
124 
125 	err = perf_evlist__open(evlist);
126 	if (err < 0) {
127 		pr_debug("perf_evlist__open: %s\n",
128 			 str_error_r(errno, sbuf, sizeof(sbuf)));
129 		goto out_delete_evlist;
130 	}
131 
132 	ret = TEST_FAIL;
133 	err = do_test(evlist, opts.mmap_pages, &sample_count,
134 		      &comm_count);
135 	if (err != TEST_OK)
136 		goto out_delete_evlist;
137 
138 	if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
139 		pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
140 		       sample_count, comm_count);
141 		goto out_delete_evlist;
142 	}
143 
144 	err = do_test(evlist, 1, &sample_count, &comm_count);
145 	if (err != TEST_OK)
146 		goto out_delete_evlist;
147 
148 	ret = TEST_OK;
149 out_delete_evlist:
150 	perf_evlist__delete(evlist);
151 	return ret;
152 }
153