tools/testing/selftests/ring-buffer/map_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Ring-buffer memory mapping tests
   4  *
   5  * Copyright (c) 2024 Vincent Donnefort <vdonnefort@google.com>
   6  */
   7 #include <fcntl.h>
   8 #include <sched.h>
   9 #include <stdbool.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13
  14 #include <linux/trace_mmap.h>
  15
  16 #include <sys/mman.h>
  17 #include <sys/ioctl.h>
  18
  19 #include "../user_events/user_events_selftests.h" /* share tracefs setup */
  20 #include "../kselftest_harness.h"
  21
  22 #define TRACEFS_ROOT "/sys/kernel/tracing"
  23
  24 static int __tracefs_write(const char *path, const char *value)
  25 {
  26         int fd, ret;
  27
  28         fd = open(path, O_WRONLY | O_TRUNC);
  29         if (fd < 0)
  30                 return fd;
  31
  32         ret = write(fd, value, strlen(value));
  33
  34         close(fd);
  35
  36         return ret == -1 ? -errno : 0;
  37 }
  38
  39 static int __tracefs_write_int(const char *path, int value)
  40 {
  41         char *str;
  42         int ret;
  43
  44         if (asprintf(&str, "%d", value) < 0)
  45                 return -1;
  46
  47         ret = __tracefs_write(path, str);
  48
  49         free(str);
  50
  51         return ret;
  52 }
  53
  54 #define tracefs_write_int(path, value) \
  55         ASSERT_EQ(__tracefs_write_int((path), (value)), 0)
  56
  57 #define tracefs_write(path, value) \
  58         ASSERT_EQ(__tracefs_write((path), (value)), 0)
  59
  60 static int tracefs_reset(void)
  61 {
  62         if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0))
  63                 return -1;
  64         if (__tracefs_write(TRACEFS_ROOT"/trace", ""))
  65                 return -1;
  66         if (__tracefs_write(TRACEFS_ROOT"/set_event", ""))
  67                 return -1;
  68         if (__tracefs_write(TRACEFS_ROOT"/current_tracer", "nop"))
  69                 return -1;
  70
  71         return 0;
  72 }
  73
  74 struct tracefs_cpu_map_desc {
  75         struct trace_buffer_meta        *meta;
  76         int                             cpu_fd;
  77 };
  78
  79 int tracefs_cpu_map(struct tracefs_cpu_map_desc *desc, int cpu)
  80 {
  81         int page_size = getpagesize();
  82         char *cpu_path;
  83         void *map;
  84
  85         if (asprintf(&cpu_path,
  86                      TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw",
  87                      cpu) < 0)
  88                 return -ENOMEM;
  89
  90         desc->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK);
  91         free(cpu_path);
  92         if (desc->cpu_fd < 0)
  93                 return -ENODEV;
  94
  95 again:
  96         map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, desc->cpu_fd, 0);
  97         if (map == MAP_FAILED)
  98                 return -errno;
  99
 100         desc->meta = (struct trace_buffer_meta *)map;
 101
 102         /* the meta-page is bigger than the original mapping */
 103         if (page_size < desc->meta->meta_struct_len) {
 104                 int meta_page_size = desc->meta->meta_page_size;
 105
 106                 munmap(desc->meta, page_size);
 107                 page_size = meta_page_size;
 108                 goto again;
 109         }
 110
 111         return 0;
 112 }
 113
 114 void tracefs_cpu_unmap(struct tracefs_cpu_map_desc *desc)
 115 {
 116         munmap(desc->meta, desc->meta->meta_page_size);
 117         close(desc->cpu_fd);
 118 }
 119
 120 FIXTURE(map) {
 121         struct tracefs_cpu_map_desc     map_desc;
 122         bool                            umount;
 123 };
 124
 125 FIXTURE_VARIANT(map) {
 126         int     subbuf_size;
 127 };
 128
 129 FIXTURE_VARIANT_ADD(map, subbuf_size_4k) {
 130         .subbuf_size = 4,
 131 };
 132
 133 FIXTURE_VARIANT_ADD(map, subbuf_size_8k) {
 134         .subbuf_size = 8,
 135 };
 136
 137 FIXTURE_SETUP(map)
 138 {
 139         int cpu = sched_getcpu();
 140         cpu_set_t cpu_mask;
 141         bool fail, umount;
 142         char *message;
 143
 144         if (getuid() != 0)
 145                 SKIP(return, "Skipping: %s", "Please run the test as root");
 146
 147         if (!tracefs_enabled(&message, &fail, &umount)) {
 148                 if (fail) {
 149                         TH_LOG("Tracefs setup failed: %s", message);
 150                         ASSERT_FALSE(fail);
 151                 }
 152                 SKIP(return, "Skipping: %s", message);
 153         }
 154
 155         self->umount = umount;
 156
 157         ASSERT_GE(cpu, 0);
 158
 159         ASSERT_EQ(tracefs_reset(), 0);
 160
 161         tracefs_write_int(TRACEFS_ROOT"/buffer_subbuf_size_kb", variant->subbuf_size);
 162
 163         ASSERT_EQ(tracefs_cpu_map(&self->map_desc, cpu), 0);
 164
 165         /*
 166          * Ensure generated events will be found on this very same ring-buffer.
 167          */
 168         CPU_ZERO(&cpu_mask);
 169         CPU_SET(cpu, &cpu_mask);
 170         ASSERT_EQ(sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask), 0);
 171 }
 172
 173 FIXTURE_TEARDOWN(map)
 174 {
 175         tracefs_reset();
 176
 177         if (self->umount)
 178                 tracefs_unmount();
 179
 180         tracefs_cpu_unmap(&self->map_desc);
 181 }
 182
 183 TEST_F(map, meta_page_check)
 184 {
 185         struct tracefs_cpu_map_desc *desc = &self->map_desc;
 186         int cnt = 0;
 187
 188         ASSERT_EQ(desc->meta->entries, 0);
 189         ASSERT_EQ(desc->meta->overrun, 0);
 190         ASSERT_EQ(desc->meta->read, 0);
 191
 192         ASSERT_EQ(desc->meta->reader.id, 0);
 193         ASSERT_EQ(desc->meta->reader.read, 0);
 194
 195         ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
 196         ASSERT_EQ(desc->meta->reader.id, 0);
 197
 198         tracefs_write_int(TRACEFS_ROOT"/tracing_on", 1);
 199         for (int i = 0; i < 16; i++)
 200                 tracefs_write_int(TRACEFS_ROOT"/trace_marker", i);
 201 again:
 202         ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
 203
 204         ASSERT_EQ(desc->meta->entries, 16);
 205         ASSERT_EQ(desc->meta->overrun, 0);
 206         ASSERT_EQ(desc->meta->read, 16);
 207
 208         ASSERT_EQ(desc->meta->reader.id, 1);
 209
 210         if (!(cnt++))
 211                 goto again;
 212 }
 213
 214 TEST_F(map, data_mmap)
 215 {
 216         struct tracefs_cpu_map_desc *desc = &self->map_desc;
 217         unsigned long meta_len, data_len;
 218         void *data;
 219
 220         meta_len = desc->meta->meta_page_size;
 221         data_len = desc->meta->subbuf_size * desc->meta->nr_subbufs;
 222
 223         /* Map all the available subbufs */
 224         data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
 225                     desc->cpu_fd, meta_len);
 226         ASSERT_NE(data, MAP_FAILED);
 227         munmap(data, data_len);
 228
 229         /* Map all the available subbufs - 1 */
 230         data_len -= desc->meta->subbuf_size;
 231         data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
 232                     desc->cpu_fd, meta_len);
 233         ASSERT_NE(data, MAP_FAILED);
 234         munmap(data, data_len);
 235
 236         /* Overflow the available subbufs by 1 */
 237         meta_len += desc->meta->subbuf_size * 2;
 238         data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
 239                     desc->cpu_fd, meta_len);
 240         ASSERT_EQ(data, MAP_FAILED);
 241
 242         /* Verify meta-page padding */
 243         if (desc->meta->meta_page_size > getpagesize()) {
 244                 data_len = desc->meta->meta_page_size;
 245                 data = mmap(NULL, data_len,
 246                             PROT_READ, MAP_SHARED, desc->cpu_fd, 0);
 247                 ASSERT_NE(data, MAP_FAILED);
 248
 249                 for (int i = desc->meta->meta_struct_len;
 250                      i < desc->meta->meta_page_size; i += sizeof(int))
 251                         ASSERT_EQ(*(int *)(data + i), 0);
 252
 253                 munmap(data, data_len);
 254         }
 255 }
 256
 257 FIXTURE(snapshot) {
 258         bool    umount;
 259 };
 260
 261 FIXTURE_SETUP(snapshot)
 262 {
 263         bool fail, umount;
 264         struct stat sb;
 265         char *message;
 266
 267         if (getuid() != 0)
 268                 SKIP(return, "Skipping: %s", "Please run the test as root");
 269
 270         if (stat(TRACEFS_ROOT"/snapshot", &sb))
 271                 SKIP(return, "Skipping: %s", "snapshot not available");
 272
 273         if (!tracefs_enabled(&message, &fail, &umount)) {
 274                 if (fail) {
 275                         TH_LOG("Tracefs setup failed: %s", message);
 276                         ASSERT_FALSE(fail);
 277                 }
 278                 SKIP(return, "Skipping: %s", message);
 279         }
 280
 281         self->umount = umount;
 282 }
 283
 284 FIXTURE_TEARDOWN(snapshot)
 285 {
 286         __tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
 287                         "!snapshot");
 288         tracefs_reset();
 289
 290         if (self->umount)
 291                 tracefs_unmount();
 292 }
 293
 294 TEST_F(snapshot, excludes_map)
 295 {
 296         struct tracefs_cpu_map_desc map_desc;
 297         int cpu = sched_getcpu();
 298
 299         ASSERT_GE(cpu, 0);
 300         tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
 301                       "snapshot");
 302         ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), -EBUSY);
 303 }
 304
 305 TEST_F(snapshot, excluded_by_map)
 306 {
 307         struct tracefs_cpu_map_desc map_desc;
 308         int cpu = sched_getcpu();
 309
 310         ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), 0);
 311
 312         ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
 313                                   "snapshot"), -EBUSY);
 314         ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/snapshot",
 315                                   "1"), -EBUSY);
 316 }
 317
 318 TEST_HARNESS_MAIN