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