1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Test backward bit in event attribute, read ring buffer from end to
4  * beginning
5  */
6 
7 #include <evlist.h>
8 #include <sys/prctl.h>
9 #include "record.h"
10 #include "tests.h"
11 #include "debug.h"
12 #include "parse-events.h"
13 #include "util/mmap.h"
14 #include <errno.h>
15 #include <linux/string.h>
16 #include <perf/mmap.h>
17 
18 #define NR_ITERS 111
19 
20 static void testcase(void)
21 {
22 	int i;
23 
24 	for (i = 0; i < NR_ITERS; i++) {
25 		char proc_name[15];
26 
27 		snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
28 		prctl(PR_SET_NAME, proc_name);
29 	}
30 }
31 
32 static int count_samples(struct evlist *evlist, int *sample_count,
33 			 int *comm_count)
34 {
35 	int i;
36 
37 	for (i = 0; i < evlist->core.nr_mmaps; i++) {
38 		struct mmap *map = &evlist->overwrite_mmap[i];
39 		union perf_event *event;
40 
41 		perf_mmap__read_init(&map->core);
42 		while ((event = perf_mmap__read_event(&map->core)) != NULL) {
43 			const u32 type = event->header.type;
44 
45 			switch (type) {
46 			case PERF_RECORD_SAMPLE:
47 				(*sample_count)++;
48 				break;
49 			case PERF_RECORD_COMM:
50 				(*comm_count)++;
51 				break;
52 			default:
53 				pr_err("Unexpected record of type %d\n", type);
54 				return TEST_FAIL;
55 			}
56 		}
57 		perf_mmap__read_done(&map->core);
58 	}
59 	return TEST_OK;
60 }
61 
62 static int do_test(struct evlist *evlist, int mmap_pages,
63 		   int *sample_count, int *comm_count)
64 {
65 	int err;
66 	char sbuf[STRERR_BUFSIZE];
67 
68 	err = evlist__mmap(evlist, mmap_pages);
69 	if (err < 0) {
70 		pr_debug("evlist__mmap: %s\n",
71 			 str_error_r(errno, sbuf, sizeof(sbuf)));
72 		return TEST_FAIL;
73 	}
74 
75 	evlist__enable(evlist);
76 	testcase();
77 	evlist__disable(evlist);
78 
79 	err = count_samples(evlist, sample_count, comm_count);
80 	evlist__munmap(evlist);
81 	return err;
82 }
83 
84 
85 static int test__backward_ring_buffer(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
86 {
87 	int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0;
88 	char pid[16], sbuf[STRERR_BUFSIZE];
89 	struct evlist *evlist;
90 	struct evsel *evsel __maybe_unused;
91 	struct parse_events_error parse_error;
92 	struct record_opts opts = {
93 		.target = {
94 			.uid = UINT_MAX,
95 			.uses_mmap = true,
96 		},
97 		.freq	      = 0,
98 		.mmap_pages   = 256,
99 		.default_interval = 1,
100 	};
101 
102 	snprintf(pid, sizeof(pid), "%d", getpid());
103 	pid[sizeof(pid) - 1] = '\0';
104 	opts.target.tid = opts.target.pid = pid;
105 
106 	evlist = evlist__new();
107 	if (!evlist) {
108 		pr_debug("Not enough memory to create evlist\n");
109 		return TEST_FAIL;
110 	}
111 
112 	err = evlist__create_maps(evlist, &opts.target);
113 	if (err < 0) {
114 		pr_debug("Not enough memory to create thread/cpu maps\n");
115 		goto out_delete_evlist;
116 	}
117 
118 	parse_events_error__init(&parse_error);
119 	/*
120 	 * Set backward bit, ring buffer should be writing from end. Record
121 	 * it in aux evlist
122 	 */
123 	err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);
124 	parse_events_error__exit(&parse_error);
125 	if (err) {
126 		pr_debug("Failed to parse tracepoint event, try use root\n");
127 		ret = TEST_SKIP;
128 		goto out_delete_evlist;
129 	}
130 
131 	evlist__config(evlist, &opts, NULL);
132 
133 	err = evlist__open(evlist);
134 	if (err < 0) {
135 		pr_debug("perf_evlist__open: %s\n",
136 			 str_error_r(errno, sbuf, sizeof(sbuf)));
137 		goto out_delete_evlist;
138 	}
139 
140 	ret = TEST_FAIL;
141 	err = do_test(evlist, opts.mmap_pages, &sample_count,
142 		      &comm_count);
143 	if (err != TEST_OK)
144 		goto out_delete_evlist;
145 
146 	if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
147 		pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
148 		       sample_count, comm_count);
149 		goto out_delete_evlist;
150 	}
151 
152 	evlist__close(evlist);
153 
154 	err = evlist__open(evlist);
155 	if (err < 0) {
156 		pr_debug("perf_evlist__open: %s\n",
157 			 str_error_r(errno, sbuf, sizeof(sbuf)));
158 		goto out_delete_evlist;
159 	}
160 
161 	err = do_test(evlist, 1, &sample_count, &comm_count);
162 	if (err != TEST_OK)
163 		goto out_delete_evlist;
164 
165 	ret = TEST_OK;
166 out_delete_evlist:
167 	evlist__delete(evlist);
168 	return ret;
169 }
170 
171 DEFINE_SUITE("Read backward ring buffer", backward_ring_buffer);
172