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 "dso.h"
  14 #include <internal/lib.h>
  15 #include "map.h"
  16 #include "symbol.h"
  17 #include "machine.h"
  18 #include "thread.h"
  19 #include "linux/string.h"
  20 #include <linux/zalloc.h>
  21 #include "debug.h"
  22
  23 /*
  24  * Include definition of find_map() also used in perf-read-vdso.c for
  25  * building perf-read-vdso32 and perf-read-vdsox32.
  26  */
  27 #include "find-map.c"
  28
  29 #define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX"
  30
  31 struct vdso_file {
  32         bool found;
  33         bool error;
  34         char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)];
  35         const char *dso_name;
  36         const char *read_prog;
  37 };
  38
  39 struct vdso_info {
  40         struct vdso_file vdso;
  41 #if BITS_PER_LONG == 64
  42         struct vdso_file vdso32;
  43         struct vdso_file vdsox32;
  44 #endif
  45 };
  46
  47 static struct vdso_info *vdso_info__new(void)
  48 {
  49         static const struct vdso_info vdso_info_init = {
  50                 .vdso    = {
  51                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  52                         .dso_name = DSO__NAME_VDSO,
  53                 },
  54 #if BITS_PER_LONG == 64
  55                 .vdso32  = {
  56                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  57                         .dso_name = DSO__NAME_VDSO32,
  58                         .read_prog = "perf-read-vdso32",
  59                 },
  60                 .vdsox32  = {
  61                         .temp_file_name = VDSO__TEMP_FILE_NAME,
  62                         .dso_name = DSO__NAME_VDSOX32,
  63                         .read_prog = "perf-read-vdsox32",
  64                 },
  65 #endif
  66         };
  67
  68         return memdup(&vdso_info_init, sizeof(vdso_info_init));
  69 }
  70
  71 static char *get_file(struct vdso_file *vdso_file)
  72 {
  73         char *vdso = NULL;
  74         char *buf = NULL;
  75         void *start, *end;
  76         size_t size;
  77         int fd;
  78
  79         if (vdso_file->found)
  80                 return vdso_file->temp_file_name;
  81
  82         if (vdso_file->error || find_map(&start, &end, VDSO__MAP_NAME))
  83                 return NULL;
  84
  85         size = end - start;
  86
  87         buf = memdup(start, size);
  88         if (!buf)
  89                 return NULL;
  90
  91         fd = mkstemp(vdso_file->temp_file_name);
  92         if (fd < 0)
  93                 goto out;
  94
  95         if (size == (size_t) write(fd, buf, size))
  96                 vdso = vdso_file->temp_file_name;
  97
  98         close(fd);
  99
 100  out:
 101         free(buf);
 102
 103         vdso_file->found = (vdso != NULL);
 104         vdso_file->error = !vdso_file->found;
 105         return vdso;
 106 }
 107
 108 void machine__exit_vdso(struct machine *machine)
 109 {
 110         struct vdso_info *vdso_info = machine->vdso_info;
 111
 112         if (!vdso_info)
 113                 return;
 114
 115         if (vdso_info->vdso.found)
 116                 unlink(vdso_info->vdso.temp_file_name);
 117 #if BITS_PER_LONG == 64
 118         if (vdso_info->vdso32.found)
 119                 unlink(vdso_info->vdso32.temp_file_name);
 120         if (vdso_info->vdsox32.found)
 121                 unlink(vdso_info->vdsox32.temp_file_name);
 122 #endif
 123
 124         zfree(&machine->vdso_info);
 125 }
 126
 127 static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name,
 128                                           const char *long_name)
 129 {
 130         struct dso *dso;
 131
 132         dso = dso__new(short_name);
 133         if (dso != NULL) {
 134                 __dsos__add(&machine->dsos, dso);
 135                 dso__set_long_name(dso, long_name, false);
 136                 /* Put dso here because __dsos_add already got it */
 137                 dso__put(dso);
 138         }
 139
 140         return dso;
 141 }
 142
 143 static enum dso_type machine__thread_dso_type(struct machine *machine,
 144                                               struct thread *thread)
 145 {
 146         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
 147         struct map *map;
 148
 149         maps__for_each_entry(thread->maps, map) {
 150                 struct dso *dso = map->dso;
 151                 if (!dso || dso->long_name[0] != '/')
 152                         continue;
 153                 dso_type = dso__type(dso, machine);
 154                 if (dso_type != DSO__TYPE_UNKNOWN)
 155                         break;
 156         }
 157
 158         return dso_type;
 159 }
 160
 161 #if BITS_PER_LONG == 64
 162
 163 static int vdso__do_copy_compat(FILE *f, int fd)
 164 {
 165         char buf[4096];
 166         size_t count;
 167
 168         while (1) {
 169                 count = fread(buf, 1, sizeof(buf), f);
 170                 if (ferror(f))
 171                         return -errno;
 172                 if (feof(f))
 173                         break;
 174                 if (count && writen(fd, buf, count) != (ssize_t)count)
 175                         return -errno;
 176         }
 177
 178         return 0;
 179 }
 180
 181 static int vdso__copy_compat(const char *prog, int fd)
 182 {
 183         FILE *f;
 184         int err;
 185
 186         f = popen(prog, "r");
 187         if (!f)
 188                 return -errno;
 189
 190         err = vdso__do_copy_compat(f, fd);
 191
 192         if (pclose(f) == -1)
 193                 return -errno;
 194
 195         return err;
 196 }
 197
 198 static int vdso__create_compat_file(const char *prog, char *temp_name)
 199 {
 200         int fd, err;
 201
 202         fd = mkstemp(temp_name);
 203         if (fd < 0)
 204                 return -errno;
 205
 206         err = vdso__copy_compat(prog, fd);
 207
 208         if (close(fd) == -1)
 209                 return -errno;
 210
 211         return err;
 212 }
 213
 214 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 215 {
 216         int err;
 217
 218         if (vdso_file->found)
 219                 return vdso_file->temp_file_name;
 220
 221         if (vdso_file->error)
 222                 return NULL;
 223
 224         err = vdso__create_compat_file(vdso_file->read_prog,
 225                                        vdso_file->temp_file_name);
 226         if (err) {
 227                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 228                 vdso_file->error = true;
 229                 return NULL;
 230         }
 231
 232         vdso_file->found = true;
 233
 234         return vdso_file->temp_file_name;
 235 }
 236
 237 static struct dso *__machine__findnew_compat(struct machine *machine,
 238                                              struct vdso_file *vdso_file)
 239 {
 240         const char *file_name;
 241         struct dso *dso;
 242
 243         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 244         if (dso)
 245                 goto out;
 246
 247         file_name = vdso__get_compat_file(vdso_file);
 248         if (!file_name)
 249                 goto out;
 250
 251         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 252 out:
 253         return dso;
 254 }
 255
 256 static int __machine__findnew_vdso_compat(struct machine *machine,
 257                                           struct thread *thread,
 258                                           struct vdso_info *vdso_info,
 259                                           struct dso **dso)
 260 {
 261         enum dso_type dso_type;
 262
 263         dso_type = machine__thread_dso_type(machine, thread);
 264
 265 #ifndef HAVE_PERF_READ_VDSO32
 266         if (dso_type == DSO__TYPE_32BIT)
 267                 return 0;
 268 #endif
 269 #ifndef HAVE_PERF_READ_VDSOX32
 270         if (dso_type == DSO__TYPE_X32BIT)
 271                 return 0;
 272 #endif
 273
 274         switch (dso_type) {
 275         case DSO__TYPE_32BIT:
 276                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 277                 return 1;
 278         case DSO__TYPE_X32BIT:
 279                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 280                 return 1;
 281         case DSO__TYPE_UNKNOWN:
 282         case DSO__TYPE_64BIT:
 283         default:
 284                 return 0;
 285         }
 286 }
 287
 288 #endif
 289
 290 static struct dso *machine__find_vdso(struct machine *machine,
 291                                       struct thread *thread)
 292 {
 293         struct dso *dso = NULL;
 294         enum dso_type dso_type;
 295
 296         dso_type = machine__thread_dso_type(machine, thread);
 297         switch (dso_type) {
 298         case DSO__TYPE_32BIT:
 299                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 300                 if (!dso) {
 301                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 302                                            true);
 303                         if (dso && dso_type != dso__type(dso, machine))
 304                                 dso = NULL;
 305                 }
 306                 break;
 307         case DSO__TYPE_X32BIT:
 308                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 309                 break;
 310         case DSO__TYPE_64BIT:
 311         case DSO__TYPE_UNKNOWN:
 312         default:
 313                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 314                 break;
 315         }
 316
 317         return dso;
 318 }
 319
 320 struct dso *machine__findnew_vdso(struct machine *machine,
 321                                   struct thread *thread)
 322 {
 323         struct vdso_info *vdso_info;
 324         struct dso *dso = NULL;
 325
 326         down_write(&machine->dsos.lock);
 327         if (!machine->vdso_info)
 328                 machine->vdso_info = vdso_info__new();
 329
 330         vdso_info = machine->vdso_info;
 331         if (!vdso_info)
 332                 goto out_unlock;
 333
 334         dso = machine__find_vdso(machine, thread);
 335         if (dso)
 336                 goto out_unlock;
 337
 338 #if BITS_PER_LONG == 64
 339         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 340                 goto out_unlock;
 341 #endif
 342
 343         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 344         if (!dso) {
 345                 char *file;
 346
 347                 file = get_file(&vdso_info->vdso);
 348                 if (file)
 349                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 350         }
 351
 352 out_unlock:
 353         dso__get(dso);
 354         up_write(&machine->dsos.lock);
 355         return dso;
 356 }
 357
 358 bool dso__is_vdso(struct dso *dso)
 359 {
 360         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 361                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 362                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 363 }