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;
 143         struct dso *dso;
 144
 145         map = map_groups__first(thread->mg, MAP__FUNCTION);
 146         for (; map ; map = map_groups__next(map)) {
 147                 dso = map->dso;
 148                 if (!dso || dso->long_name[0] != '/')
 149                         continue;
 150                 dso_type = dso__type(dso, machine);
 151                 if (dso_type != DSO__TYPE_UNKNOWN)
 152                         break;
 153         }
 154
 155         return dso_type;
 156 }
 157
 158 #if BITS_PER_LONG == 64
 159
 160 static int vdso__do_copy_compat(FILE *f, int fd)
 161 {
 162         char buf[4096];
 163         size_t count;
 164
 165         while (1) {
 166                 count = fread(buf, 1, sizeof(buf), f);
 167                 if (ferror(f))
 168                         return -errno;
 169                 if (feof(f))
 170                         break;
 171                 if (count && writen(fd, buf, count) != (ssize_t)count)
 172                         return -errno;
 173         }
 174
 175         return 0;
 176 }
 177
 178 static int vdso__copy_compat(const char *prog, int fd)
 179 {
 180         FILE *f;
 181         int err;
 182
 183         f = popen(prog, "r");
 184         if (!f)
 185                 return -errno;
 186
 187         err = vdso__do_copy_compat(f, fd);
 188
 189         if (pclose(f) == -1)
 190                 return -errno;
 191
 192         return err;
 193 }
 194
 195 static int vdso__create_compat_file(const char *prog, char *temp_name)
 196 {
 197         int fd, err;
 198
 199         fd = mkstemp(temp_name);
 200         if (fd < 0)
 201                 return -errno;
 202
 203         err = vdso__copy_compat(prog, fd);
 204
 205         if (close(fd) == -1)
 206                 return -errno;
 207
 208         return err;
 209 }
 210
 211 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 212 {
 213         int err;
 214
 215         if (vdso_file->found)
 216                 return vdso_file->temp_file_name;
 217
 218         if (vdso_file->error)
 219                 return NULL;
 220
 221         err = vdso__create_compat_file(vdso_file->read_prog,
 222                                        vdso_file->temp_file_name);
 223         if (err) {
 224                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 225                 vdso_file->error = true;
 226                 return NULL;
 227         }
 228
 229         vdso_file->found = true;
 230
 231         return vdso_file->temp_file_name;
 232 }
 233
 234 static struct dso *__machine__findnew_compat(struct machine *machine,
 235                                              struct vdso_file *vdso_file)
 236 {
 237         const char *file_name;
 238         struct dso *dso;
 239
 240         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 241         if (dso)
 242                 goto out;
 243
 244         file_name = vdso__get_compat_file(vdso_file);
 245         if (!file_name)
 246                 goto out;
 247
 248         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 249 out:
 250         return dso;
 251 }
 252
 253 static int __machine__findnew_vdso_compat(struct machine *machine,
 254                                           struct thread *thread,
 255                                           struct vdso_info *vdso_info,
 256                                           struct dso **dso)
 257 {
 258         enum dso_type dso_type;
 259
 260         dso_type = machine__thread_dso_type(machine, thread);
 261
 262 #ifndef HAVE_PERF_READ_VDSO32
 263         if (dso_type == DSO__TYPE_32BIT)
 264                 return 0;
 265 #endif
 266 #ifndef HAVE_PERF_READ_VDSOX32
 267         if (dso_type == DSO__TYPE_X32BIT)
 268                 return 0;
 269 #endif
 270
 271         switch (dso_type) {
 272         case DSO__TYPE_32BIT:
 273                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 274                 return 1;
 275         case DSO__TYPE_X32BIT:
 276                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 277                 return 1;
 278         case DSO__TYPE_UNKNOWN:
 279         case DSO__TYPE_64BIT:
 280         default:
 281                 return 0;
 282         }
 283 }
 284
 285 #endif
 286
 287 static struct dso *machine__find_vdso(struct machine *machine,
 288                                       struct thread *thread)
 289 {
 290         struct dso *dso = NULL;
 291         enum dso_type dso_type;
 292
 293         dso_type = machine__thread_dso_type(machine, thread);
 294         switch (dso_type) {
 295         case DSO__TYPE_32BIT:
 296                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 297                 if (!dso) {
 298                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 299                                            true);
 300                         if (dso && dso_type != dso__type(dso, machine))
 301                                 dso = NULL;
 302                 }
 303                 break;
 304         case DSO__TYPE_X32BIT:
 305                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 306                 break;
 307         case DSO__TYPE_64BIT:
 308         case DSO__TYPE_UNKNOWN:
 309         default:
 310                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 311                 break;
 312         }
 313
 314         return dso;
 315 }
 316
 317 struct dso *machine__findnew_vdso(struct machine *machine,
 318                                   struct thread *thread)
 319 {
 320         struct vdso_info *vdso_info;
 321         struct dso *dso = NULL;
 322
 323         down_write(&machine->dsos.lock);
 324         if (!machine->vdso_info)
 325                 machine->vdso_info = vdso_info__new();
 326
 327         vdso_info = machine->vdso_info;
 328         if (!vdso_info)
 329                 goto out_unlock;
 330
 331         dso = machine__find_vdso(machine, thread);
 332         if (dso)
 333                 goto out_unlock;
 334
 335 #if BITS_PER_LONG == 64
 336         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 337                 goto out_unlock;
 338 #endif
 339
 340         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 341         if (!dso) {
 342                 char *file;
 343
 344                 file = get_file(&vdso_info->vdso);
 345                 if (file)
 346                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 347         }
 348
 349 out_unlock:
 350         dso__get(dso);
 351         up_write(&machine->dsos.lock);
 352         return dso;
 353 }
 354
 355 bool dso__is_vdso(struct dso *dso)
 356 {
 357         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 358                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 359                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 360 }