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_rb_node *rb_node;
 148
 149         maps__for_each_entry(thread__maps(thread), rb_node) {
 150                 struct dso *dso = map__dso(rb_node->map);
 151
 152                 if (!dso || dso->long_name[0] != '/')
 153                         continue;
 154                 dso_type = dso__type(dso, machine);
 155                 if (dso_type != DSO__TYPE_UNKNOWN)
 156                         break;
 157         }
 158
 159         return dso_type;
 160 }
 161
 162 #if BITS_PER_LONG == 64
 163
 164 static int vdso__do_copy_compat(FILE *f, int fd)
 165 {
 166         char buf[4096];
 167         size_t count;
 168
 169         while (1) {
 170                 count = fread(buf, 1, sizeof(buf), f);
 171                 if (ferror(f))
 172                         return -errno;
 173                 if (feof(f))
 174                         break;
 175                 if (count && writen(fd, buf, count) != (ssize_t)count)
 176                         return -errno;
 177         }
 178
 179         return 0;
 180 }
 181
 182 static int vdso__copy_compat(const char *prog, int fd)
 183 {
 184         FILE *f;
 185         int err;
 186
 187         f = popen(prog, "r");
 188         if (!f)
 189                 return -errno;
 190
 191         err = vdso__do_copy_compat(f, fd);
 192
 193         if (pclose(f) == -1)
 194                 return -errno;
 195
 196         return err;
 197 }
 198
 199 static int vdso__create_compat_file(const char *prog, char *temp_name)
 200 {
 201         int fd, err;
 202
 203         fd = mkstemp(temp_name);
 204         if (fd < 0)
 205                 return -errno;
 206
 207         err = vdso__copy_compat(prog, fd);
 208
 209         if (close(fd) == -1)
 210                 return -errno;
 211
 212         return err;
 213 }
 214
 215 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 216 {
 217         int err;
 218
 219         if (vdso_file->found)
 220                 return vdso_file->temp_file_name;
 221
 222         if (vdso_file->error)
 223                 return NULL;
 224
 225         err = vdso__create_compat_file(vdso_file->read_prog,
 226                                        vdso_file->temp_file_name);
 227         if (err) {
 228                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 229                 vdso_file->error = true;
 230                 return NULL;
 231         }
 232
 233         vdso_file->found = true;
 234
 235         return vdso_file->temp_file_name;
 236 }
 237
 238 static struct dso *__machine__findnew_compat(struct machine *machine,
 239                                              struct vdso_file *vdso_file)
 240 {
 241         const char *file_name;
 242         struct dso *dso;
 243
 244         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 245         if (dso)
 246                 goto out;
 247
 248         file_name = vdso__get_compat_file(vdso_file);
 249         if (!file_name)
 250                 goto out;
 251
 252         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 253 out:
 254         return dso;
 255 }
 256
 257 static int __machine__findnew_vdso_compat(struct machine *machine,
 258                                           struct thread *thread,
 259                                           struct vdso_info *vdso_info,
 260                                           struct dso **dso)
 261 {
 262         enum dso_type dso_type;
 263
 264         dso_type = machine__thread_dso_type(machine, thread);
 265
 266 #ifndef HAVE_PERF_READ_VDSO32
 267         if (dso_type == DSO__TYPE_32BIT)
 268                 return 0;
 269 #endif
 270 #ifndef HAVE_PERF_READ_VDSOX32
 271         if (dso_type == DSO__TYPE_X32BIT)
 272                 return 0;
 273 #endif
 274
 275         switch (dso_type) {
 276         case DSO__TYPE_32BIT:
 277                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 278                 return 1;
 279         case DSO__TYPE_X32BIT:
 280                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 281                 return 1;
 282         case DSO__TYPE_UNKNOWN:
 283         case DSO__TYPE_64BIT:
 284         default:
 285                 return 0;
 286         }
 287 }
 288
 289 #endif
 290
 291 static struct dso *machine__find_vdso(struct machine *machine,
 292                                       struct thread *thread)
 293 {
 294         struct dso *dso = NULL;
 295         enum dso_type dso_type;
 296
 297         dso_type = machine__thread_dso_type(machine, thread);
 298         switch (dso_type) {
 299         case DSO__TYPE_32BIT:
 300                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 301                 if (!dso) {
 302                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 303                                            true);
 304                         if (dso && dso_type != dso__type(dso, machine))
 305                                 dso = NULL;
 306                 }
 307                 break;
 308         case DSO__TYPE_X32BIT:
 309                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 310                 break;
 311         case DSO__TYPE_64BIT:
 312         case DSO__TYPE_UNKNOWN:
 313         default:
 314                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 315                 break;
 316         }
 317
 318         return dso;
 319 }
 320
 321 struct dso *machine__findnew_vdso(struct machine *machine,
 322                                   struct thread *thread)
 323 {
 324         struct vdso_info *vdso_info;
 325         struct dso *dso = NULL;
 326
 327         down_write(&machine->dsos.lock);
 328         if (!machine->vdso_info)
 329                 machine->vdso_info = vdso_info__new();
 330
 331         vdso_info = machine->vdso_info;
 332         if (!vdso_info)
 333                 goto out_unlock;
 334
 335         dso = machine__find_vdso(machine, thread);
 336         if (dso)
 337                 goto out_unlock;
 338
 339 #if BITS_PER_LONG == 64
 340         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 341                 goto out_unlock;
 342 #endif
 343
 344         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 345         if (!dso) {
 346                 char *file;
 347
 348                 file = get_file(&vdso_info->vdso);
 349                 if (file)
 350                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 351         }
 352
 353 out_unlock:
 354         dso__get(dso);
 355         up_write(&machine->dsos.lock);
 356         return dso;
 357 }
 358
 359 bool dso__is_vdso(struct dso *dso)
 360 {
 361         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 362                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 363                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 364 }