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         }
 137
 138         return dso;
 139 }
 140
 141 static enum dso_type machine__thread_dso_type(struct machine *machine,
 142                                               struct thread *thread)
 143 {
 144         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
 145         struct map *map;
 146
 147         maps__for_each_entry(thread->maps, map) {
 148                 struct dso *dso = map->dso;
 149                 if (!dso || dso->long_name[0] != '/')
 150                         continue;
 151                 dso_type = dso__type(dso, machine);
 152                 if (dso_type != DSO__TYPE_UNKNOWN)
 153                         break;
 154         }
 155
 156         return dso_type;
 157 }
 158
 159 #if BITS_PER_LONG == 64
 160
 161 static int vdso__do_copy_compat(FILE *f, int fd)
 162 {
 163         char buf[4096];
 164         size_t count;
 165
 166         while (1) {
 167                 count = fread(buf, 1, sizeof(buf), f);
 168                 if (ferror(f))
 169                         return -errno;
 170                 if (feof(f))
 171                         break;
 172                 if (count && writen(fd, buf, count) != (ssize_t)count)
 173                         return -errno;
 174         }
 175
 176         return 0;
 177 }
 178
 179 static int vdso__copy_compat(const char *prog, int fd)
 180 {
 181         FILE *f;
 182         int err;
 183
 184         f = popen(prog, "r");
 185         if (!f)
 186                 return -errno;
 187
 188         err = vdso__do_copy_compat(f, fd);
 189
 190         if (pclose(f) == -1)
 191                 return -errno;
 192
 193         return err;
 194 }
 195
 196 static int vdso__create_compat_file(const char *prog, char *temp_name)
 197 {
 198         int fd, err;
 199
 200         fd = mkstemp(temp_name);
 201         if (fd < 0)
 202                 return -errno;
 203
 204         err = vdso__copy_compat(prog, fd);
 205
 206         if (close(fd) == -1)
 207                 return -errno;
 208
 209         return err;
 210 }
 211
 212 static const char *vdso__get_compat_file(struct vdso_file *vdso_file)
 213 {
 214         int err;
 215
 216         if (vdso_file->found)
 217                 return vdso_file->temp_file_name;
 218
 219         if (vdso_file->error)
 220                 return NULL;
 221
 222         err = vdso__create_compat_file(vdso_file->read_prog,
 223                                        vdso_file->temp_file_name);
 224         if (err) {
 225                 pr_err("%s failed, error %d\n", vdso_file->read_prog, err);
 226                 vdso_file->error = true;
 227                 return NULL;
 228         }
 229
 230         vdso_file->found = true;
 231
 232         return vdso_file->temp_file_name;
 233 }
 234
 235 static struct dso *__machine__findnew_compat(struct machine *machine,
 236                                              struct vdso_file *vdso_file)
 237 {
 238         const char *file_name;
 239         struct dso *dso;
 240
 241         dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
 242         if (dso)
 243                 goto out;
 244
 245         file_name = vdso__get_compat_file(vdso_file);
 246         if (!file_name)
 247                 goto out;
 248
 249         dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 250 out:
 251         return dso;
 252 }
 253
 254 static int __machine__findnew_vdso_compat(struct machine *machine,
 255                                           struct thread *thread,
 256                                           struct vdso_info *vdso_info,
 257                                           struct dso **dso)
 258 {
 259         enum dso_type dso_type;
 260
 261         dso_type = machine__thread_dso_type(machine, thread);
 262
 263 #ifndef HAVE_PERF_READ_VDSO32
 264         if (dso_type == DSO__TYPE_32BIT)
 265                 return 0;
 266 #endif
 267 #ifndef HAVE_PERF_READ_VDSOX32
 268         if (dso_type == DSO__TYPE_X32BIT)
 269                 return 0;
 270 #endif
 271
 272         switch (dso_type) {
 273         case DSO__TYPE_32BIT:
 274                 *dso = __machine__findnew_compat(machine, &vdso_info->vdso32);
 275                 return 1;
 276         case DSO__TYPE_X32BIT:
 277                 *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32);
 278                 return 1;
 279         case DSO__TYPE_UNKNOWN:
 280         case DSO__TYPE_64BIT:
 281         default:
 282                 return 0;
 283         }
 284 }
 285
 286 #endif
 287
 288 static struct dso *machine__find_vdso(struct machine *machine,
 289                                       struct thread *thread)
 290 {
 291         struct dso *dso = NULL;
 292         enum dso_type dso_type;
 293
 294         dso_type = machine__thread_dso_type(machine, thread);
 295         switch (dso_type) {
 296         case DSO__TYPE_32BIT:
 297                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 298                 if (!dso) {
 299                         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 300                                            true);
 301                         if (dso && dso_type != dso__type(dso, machine))
 302                                 dso = NULL;
 303                 }
 304                 break;
 305         case DSO__TYPE_X32BIT:
 306                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 307                 break;
 308         case DSO__TYPE_64BIT:
 309         case DSO__TYPE_UNKNOWN:
 310         default:
 311                 dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 312                 break;
 313         }
 314
 315         return dso;
 316 }
 317
 318 struct dso *machine__findnew_vdso(struct machine *machine,
 319                                   struct thread *thread)
 320 {
 321         struct vdso_info *vdso_info;
 322         struct dso *dso = NULL;
 323
 324         down_write(&machine->dsos.lock);
 325         if (!machine->vdso_info)
 326                 machine->vdso_info = vdso_info__new();
 327
 328         vdso_info = machine->vdso_info;
 329         if (!vdso_info)
 330                 goto out_unlock;
 331
 332         dso = machine__find_vdso(machine, thread);
 333         if (dso)
 334                 goto out_unlock;
 335
 336 #if BITS_PER_LONG == 64
 337         if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
 338                 goto out_unlock;
 339 #endif
 340
 341         dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 342         if (!dso) {
 343                 char *file;
 344
 345                 file = get_file(&vdso_info->vdso);
 346                 if (file)
 347                         dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 348         }
 349
 350 out_unlock:
 351         dso__get(dso);
 352         up_write(&machine->dsos.lock);
 353         return dso;
 354 }
 355
 356 bool dso__is_vdso(struct dso *dso)
 357 {
 358         return !strcmp(dso->short_name, DSO__NAME_VDSO) ||
 359                !strcmp(dso->short_name, DSO__NAME_VDSO32) ||
 360                !strcmp(dso->short_name, DSO__NAME_VDSOX32);
 361 }