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