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 
14 static 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 
26 static 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_evlist__mmap_read_catchup(evlist, i);
35 		while ((event = perf_evlist__mmap_read_backward(evlist, 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 
54 static 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 			 strerror_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 
77 int 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("No ehough 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 	err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error);
112 	if (err) {
113 		pr_debug("Failed to parse tracepoint event, try use root\n");
114 		ret = TEST_SKIP;
115 		goto out_delete_evlist;
116 	}
117 
118 	perf_evlist__config(evlist, &opts, NULL);
119 
120 	/* Set backward bit, ring buffer should be writing from end */
121 	evlist__for_each(evlist, evsel)
122 		evsel->attr.write_backward = 1;
123 
124 	err = perf_evlist__open(evlist);
125 	if (err < 0) {
126 		pr_debug("perf_evlist__open: %s\n",
127 			 strerror_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;
148 out_delete_evlist:
149 	perf_evlist__delete(evlist);
150 	return ret;
151 }
152