tools/perf/tests/backward-ring-buffer.c

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