tools/perf/util/vdso.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <errno.h>
   3 #include <unistd.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9 #include <stdlib.h>
  10 #include <linux/kernel.h>
  11
  12 #include "vdso.h"
  13 #include "util.h"
  14 #include "symbol.h"
  15 #include "machine.h"
  16 #include "thread.h"
  17 #include "linux/string.h"
  18 #include "debug.h"
  19
  20 /*
  21  * Include definition of find_vdso_map() also used in perf-read-vdso.c for
  22  * building perf-read-vdso32 and perf-read-vdsox32.
  23  */
  24 #include "find-vdso-map.c"
  25
  26 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
  27
  28 struct vdso_file {
  29         bool found;
  30         bool error;
  31         char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
  32         const char *dso_name;
  33         const char *read_prog;
  34 };
  35
  36 struct vdso_info {
  37         struct vdso_file vdso;
  38 #if BITS_PER_LONG == 64
  39         struct vdso_file vdso32;
  40         struct vdso_file vdsox32;
  41 #endif
  42 };
  43
  44 static struct vdso_info *vdso_info__new(void)
  45 {
  46         static const struct vdso_info vdso_info_init = {
  47                 .vdso    = {
  48                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  49                         .dso_name = DSO__NAME_VDSO,
  50                 },
  51 #if BITS_PER_LONG == 64
  52                 .vdso32  = {
  53                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  54                         .dso_name = DSO__NAME_VDSO32,
  55                         .read_prog = "perf-read-vdso32",
  56                 },
  57                 .vdsox32  = {
  58                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  59                         .dso_name = DSO__NAME_VDSOX32,
  60                         .read_prog = "perf-read-vdsox32",
  61                 },
  62 #endif
  63         };
  64
  65         return memdup(&vdso_info_init, sizeof(vdso_info_init));
  66 }
  67
  68 static char *get_file(struct vdso_file *vdso_file)
  69 {
  70         char *vdso = NULL;
  71         char *buf = NULL;
  72         void *start, *end;
  73         size_t size;
  74         int fd;
  75
  76         if (vdso_file->found)
  77                 return vdso_file->temp_file_name;
  78
  79         if (vdso_file->error || find_vdso_map(&start, &end))
  80                 return NULL;
  81
  82         size = end - start;
  83
  84         buf = memdup(start, size);
  85         if (!buf)
  86                 return NULL;
  87
  88         fd = mkstemp(vdso_file->temp_file_name);
  89         if (fd < 0)
  90                 goto out;
  91
  92         if (size == (size_t) write(fd, buf, size))
  93                 vdso = vdso_file->temp_file_name;
  94
  95         close(fd);
  96
  97  out:
  98         free(buf);
  99
 100         vdso_file->found = (vdso != NULL);
 101         vdso_file->error = !vdso_file->found;
 102         return vdso;
 103 }
 104
 105 void machine__exit_vdso(struct machine *machine)
 106 {
 107         struct vdso_info *vdso_info = machine->vdso_info;
 108
 109         if (!vdso_info)
 110                 return;
 111
 112         if (vdso_info->vdso.found)
 113                 unlink(vdso_info->vdso.temp_file_name);
 114 #if BITS_PER_LONG == 64
 115         if (vdso_info->vdso32.found)
 116                 unlink(vdso_info->vdso32.temp_file_name);
 117         if (vdso_info->vdsox32.found)
 118                 unlink(vdso_info->vdsox32.temp_file_name);
 119 #endif
 120
 121         zfree(&machine->vdso_info);
 122 }
 123
 124 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
 125                                           const char *long_name)
 126 {
 127         struct dso *dso;
 128
 129         dso = dso__new(short_name);
 130         if (dso != NULL) {
 131                 __dsos__add(&machine->dsos, dso);
 132                 dso__set_long_name(dso, long_name, false);
 133         }
 134
 135         return dso;
 136 }
 137
 138 static enum dso_type machine__thread_dso_type(struct machine *machine,
 139                                               struct thread *thread)
 140 {
 141         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
 142         struct map *map = map_groups__first(thread->mg);
 143
 144         for (; map ; map = map_groups__next(map)) {
 145                 struct dso *dso = map->dso;
 146                 if (!dso || dso->long_name[0] != '/')
 147                         continue;
 148                 dso_type = dso__type(dso, machine);
 149                 if (dso_type != DSO__TYPE_UNKNOWN)
 150                         break;
 151         }
 152
 153         return dso_type;
 154 }
 155
 156 #if BITS_PER_LONG == 64
 157
 158 static int vdso__do_copy_compat(FILE *f, int fd)
 159 {
 160         char buf[4096];
 161         size_t count;
 162
 163         while (1) {
 164                 count = fread(buf, 1, sizeof(buf), f);
 165                 if (ferror(f))
 166                         return -errno;
 167                 if (feof(f))
 168                         break;
 169                 if (count && writen(fd, buf, count) != (ssize_t)count)
 170                         return -errno;
 171         }
 172
 173         return 0;
 174 }
 175
 176 static int vdso__copy_compat(const char *prog, int fd)
 177 {
 178         FILE *f;
 179         int err;
 180
 181         f = popen(prog, "r");
 182         if (!f)
 183                 return -errno;
 184
 185         err = vdso__do_copy_compat(f, fd);
 186
 187         if (pclose(f) == -1)
 188                 return -errno;
 189
 190         return err;
 191 }
 192
 193 static int vdso__create_compat_file(const char *prog, char *temp_name)
 194 {
 195         int fd, err;
 196
 197         fd = mkstemp(temp_name);
 198         if (fd < 0)
 199                 return -errno;
 200
 201         err = vdso__copy_compat(prog, fd);
 202
 203         if (close(fd) == -1)
 204                 return -errno;
 205
 206         return err;
 207 }
 208
 209 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 210 {
 211         int err;
 212
 213         if (vdso_file->found)
 214                 return vdso_file->temp_file_name;
 215
 216         if (vdso_file->error)
 217                 return NULL;
 218
 219         err = vdso__create_compat_file(vdso_file->read_prog,
 220                                        vdso_file->temp_file_name);
 221         if (err) {
 222                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 223                 vdso_file->error = true;
 224                 return NULL;
 225         }
 226
 227         vdso_file->found = true;
 228
 229         return vdso_file->temp_file_name;
 230 }
 231
 232 static struct dso *__machine__findnew_compat(struct machine *machine,
 233                                              struct vdso_file *vdso_file)
 234 {
 235         const char *file_name;
 236         struct dso *dso;
 237
 238         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 239         if (dso)
 240                 goto out;
 241
 242         file_name = vdso__get_compat_file(vdso_file);
 243         if (!file_name)
 244                 goto out;
 245
 246         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 247 out:
 248         return dso;
 249 }
 250
 251 static int __machine__findnew_vdso_compat(struct machine *machine,
 252                                           struct thread *thread,
 253                                           struct vdso_info *vdso_info,
 254                                           struct dso **dso)
 255 {
 256         enum dso_type dso_type;
 257
 258         dso_type = machine__thread_dso_type(machine, thread);
 259
 260 #ifndef HAVE_PERF_READ_VDSO32
 261         if (dso_type == DSO__TYPE_32BIT)
 262                 return 0;
 263 #endif
 264 #ifndef HAVE_PERF_READ_VDSOX32
 265         if (dso_type == DSO__TYPE_X32BIT)
 266                 return 0;
 267 #endif
 268
 269         switch (dso_type) {
 270         case DSO__TYPE_32BIT:
 271                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 272                 return 1;
 273         case DSO__TYPE_X32BIT:
 274                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 275                 return 1;
 276         case DSO__TYPE_UNKNOWN:
 277         case DSO__TYPE_64BIT:
 278         default:
 279                 return 0;
 280         }
 281 }
 282
 283 #endif
 284
 285 static struct dso *machine__find_vdso(struct machine *machine,
 286                                       struct thread *thread)
 287 {
 288         struct dso *dso = NULL;
 289         enum dso_type dso_type;
 290
 291         dso_type = machine__thread_dso_type(machine, thread);
 292         switch (dso_type) {
 293         case DSO__TYPE_32BIT:
 294                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 295                 if (!dso) {
 296                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 297                                            true);
 298                         if (dso && dso_type != dso__type(dso, machine))
 299                                 dso = NULL;
 300                 }
 301                 break;
 302         case DSO__TYPE_X32BIT:
 303                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 304                 break;
 305         case DSO__TYPE_64BIT:
 306         case DSO__TYPE_UNKNOWN:
 307         default:
 308                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 309                 break;
 310         }
 311
 312         return dso;
 313 }
 314
 315 struct dso *machine__findnew_vdso(struct machine *machine,
 316                                   struct thread *thread)
 317 {
 318         struct vdso_info *vdso_info;
 319         struct dso *dso = NULL;
 320
 321         down_write(&machine->dsos.lock);
 322         if (!machine->vdso_info)
 323                 machine->vdso_info = vdso_info__new();
 324
 325         vdso_info = machine->vdso_info;
 326         if (!vdso_info)
 327                 goto out_unlock;
 328
 329         dso = machine__find_vdso(machine, thread);
 330         if (dso)
 331                 goto out_unlock;
 332
 333 #if BITS_PER_LONG == 64
 334         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 335                 goto out_unlock;
 336 #endif
 337
 338         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 339         if (!dso) {
 340                 char *file;
 341
 342                 file = get_file(&vdso_info->vdso);
 343                 if (file)
 344                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 345         }
 346
 347 out_unlock:
 348         dso__get(dso);
 349         up_write(&machine->dsos.lock);
 350         return dso;
 351 }
 352
 353 bool dso__is_vdso(struct dso *dso)
 354 {
 355         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 356                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 357                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 358 }