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_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 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 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 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 evlist->backward = true; 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 err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error); 113 if (err) { 114 pr_debug("Failed to parse tracepoint event, try use root\n"); 115 ret = TEST_SKIP; 116 goto out_delete_evlist; 117 } 118 119 perf_evlist__config(evlist, &opts, NULL); 120 121 /* Set backward bit, ring buffer should be writing from end */ 122 evlist__for_each_entry(evlist, evsel) 123 evsel->attr.write_backward = 1; 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