contrib/elftoolchain/elfcopy/segments.c

   1 /*-
   2  * Copyright (c) 2007-2010,2012 Kai Wang
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/queue.h>
  28 #include <err.h>
  29 #include <gelf.h>
  30 #include <stdint.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include "elfcopy.h"
  36
  37 ELFTC_VCSID("$Id: segments.c 3177 2015-03-30 18:19:41Z emaste $");
  38
  39 static void     insert_to_inseg_list(struct segment *seg, struct section *sec);
  40
  41 /*
  42  * elfcopy's segment handling is relatively simpler and less powerful than
  43  * libbfd. Program headers are modified or copied from input to output objects,
  44  * but never re-generated. As a result, if the input object has incorrect
  45  * program headers, the output object's program headers will remain incorrect
  46  * or become even worse.
  47  */
  48
  49 /*
  50  * Check whether a section is "loadable". If so, add it to the
  51  * corresponding segment list(s) and return 1.
  52  */
  53 int
  54 add_to_inseg_list(struct elfcopy *ecp, struct section *s)
  55 {
  56         struct segment  *seg;
  57         int              loadable;
  58
  59         if (ecp->ophnum == 0)
  60                 return (0);
  61
  62         /*
  63          * Segment is a different view of an ELF object. One segment can
  64          * contain one or more sections, and one section can be included
  65          * in one or more segments, or not included in any segment at all.
  66          * We call those sections which can be found in one or more segments
  67          * "loadable" sections, and call the rest "unloadable" sections.
  68          * We keep track of "loadable" sections in their containing
  69          * segment(s)' v_sec queue. These information are later used to
  70          * recalculate the extents of segments, when sections are removed,
  71          * for example.
  72          */
  73         loadable = 0;
  74         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
  75                 if (s->off < seg->off || (s->vma < seg->addr && !s->pseudo))
  76                         continue;
  77                 if (s->off + s->sz > seg->off + seg->fsz &&
  78                     s->type != SHT_NOBITS)
  79                         continue;
  80                 if (s->off + s->sz > seg->off + seg->msz)
  81                         continue;
  82                 if (s->vma + s->sz > seg->addr + seg->msz)
  83                         continue;
  84
  85                 insert_to_inseg_list(seg, s);
  86                 if (seg->type == PT_LOAD)
  87                         s->seg = seg;
  88                 else if (seg->type == PT_TLS)
  89                         s->seg_tls = seg;
  90                 s->lma = seg->addr + (s->off - seg->off);
  91                 loadable = 1;
  92         }
  93
  94         return (loadable);
  95 }
  96
  97 void
  98 adjust_addr(struct elfcopy *ecp)
  99 {
 100         struct section *s, *s0;
 101         struct segment *seg;
 102         struct sec_action *sac;
 103         uint64_t dl, lma, start, end;
 104         int found, i;
 105
 106         /*
 107          * Apply VMA and global LMA changes in the first iteration.
 108          */
 109         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 110
 111                 /* Only adjust loadable section's address. */
 112                 if (!s->loadable || s->seg == NULL)
 113                         continue;
 114
 115                 /* Apply global LMA adjustment. */
 116                 if (ecp->change_addr != 0)
 117                         s->lma += ecp->change_addr;
 118
 119                 if (!s->pseudo) {
 120                         /* Apply global VMA adjustment. */
 121                         if (ecp->change_addr != 0)
 122                                 s->vma += ecp->change_addr;
 123
 124                         /* Apply section VMA adjustment. */
 125                         sac = lookup_sec_act(ecp, s->name, 0);
 126                         if (sac == NULL)
 127                                 continue;
 128                         if (sac->setvma)
 129                                 s->vma = sac->vma;
 130                         if (sac->vma_adjust != 0)
 131                                 s->vma += sac->vma_adjust;
 132                 }
 133         }
 134
 135         /*
 136          * Apply sections LMA change in the second iteration.
 137          */
 138         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 139
 140                 /* Only adjust loadable section's LMA. */
 141                 if (!s->loadable || s->seg == NULL)
 142                         continue;
 143
 144                 /*
 145                  * Check if there is a LMA change request for this
 146                  * section.
 147                  */
 148                 sac = lookup_sec_act(ecp, s->name, 0);
 149                 if (sac == NULL)
 150                         continue;
 151                 if (!sac->setlma && sac->lma_adjust == 0)
 152                         continue;
 153                 lma = s->lma;
 154                 if (sac->setlma)
 155                         lma = sac->lma;
 156                 if (sac->lma_adjust != 0)
 157                         lma += sac->lma_adjust;
 158                 if (lma == s->lma)
 159                         continue;
 160
 161                 /*
 162                  * Check if the LMA change is viable.
 163                  *
 164                  * 1. Check if the new LMA is properly aligned accroding to
 165                  *    section alignment.
 166                  *
 167                  * 2. Compute the new extent of segment that contains this
 168                  *    section, make sure it doesn't overlap with other
 169                  *    segments.
 170                  */
 171 #ifdef  DEBUG
 172                 printf("LMA for section %s: %#jx\n", s->name, lma);
 173 #endif
 174
 175                 if (lma % s->align != 0)
 176                         errx(EXIT_FAILURE, "The load address %#jx for "
 177                             "section %s is not aligned to %ju",
 178                             (uintmax_t) lma, s->name, s->align);
 179
 180                 if (lma < s->lma) {
 181                         /* Move section to lower address. */
 182                         if (lma < s->lma - s->seg->addr)
 183                                 errx(EXIT_FAILURE, "Not enough space to move "
 184                                     "section %s load address to %#jx", s->name,
 185                                     (uintmax_t) lma);
 186                         start = lma - (s->lma - s->seg->addr);
 187                         if (s == s->seg->v_sec[s->seg->nsec - 1])
 188                                 end = start + s->seg->msz;
 189                         else
 190                                 end = s->seg->addr + s->seg->msz;
 191
 192                 } else {
 193                         /* Move section to upper address. */
 194                         if (s == s->seg->v_sec[0])
 195                                 start = lma;
 196                         else
 197                                 start = s->seg->addr;
 198                         end = lma + (s->seg->addr + s->seg->msz - s->lma);
 199                         if (end < start)
 200                                 errx(EXIT_FAILURE, "Not enough space to move "
 201                                     "section %s load address to %#jx", s->name,
 202                                     (uintmax_t) lma);
 203                 }
 204
 205 #ifdef  DEBUG
 206                 printf("new extent for segment containing %s: (%#jx,%#jx)\n",
 207                     s->name, start, end);
 208 #endif
 209
 210                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 211                         if (seg == s->seg || seg->type != PT_LOAD)
 212                                 continue;
 213                         if (start > seg->addr + seg->msz)
 214                                 continue;
 215                         if (end < seg->addr)
 216                                 continue;
 217                         errx(EXIT_FAILURE, "The extent of segment containing "
 218                             "section %s overlaps with segment(%#jx,%#jx)",
 219                             s->name, seg->addr, seg->addr + seg->msz);
 220                 }
 221
 222                 /*
 223                  * Update section LMA and file offset.
 224                  */
 225
 226                 if (lma < s->lma) {
 227                         /*
 228                          * To move a section to lower load address, we decrease
 229                          * the load addresses of the section and all the
 230                          * sections that are before it, and we increase the
 231                          * file offsets of all the sections that are after it.
 232                          */
 233                         dl = s->lma - lma;
 234                         for (i = 0; i < s->seg->nsec; i++) {
 235                                 s0 = s->seg->v_sec[i];
 236                                 s0->lma -= dl;
 237 #ifdef  DEBUG
 238                                 printf("section %s LMA set to %#jx\n",
 239                                     s0->name, (uintmax_t) s0->lma);
 240 #endif
 241                                 if (s0 == s)
 242                                         break;
 243                         }
 244                         for (i = i + 1; i < s->seg->nsec; i++) {
 245                                 s0 = s->seg->v_sec[i];
 246                                 s0->off += dl;
 247 #ifdef  DEBUG
 248                                 printf("section %s offset set to %#jx\n",
 249                                     s0->name, (uintmax_t) s0->off);
 250 #endif
 251                         }
 252                 } else {
 253                         /*
 254                          * To move a section to upper load address, we increase
 255                          * the load addresses of the section and all the
 256                          * sections that are after it, and we increase the
 257                          * their file offsets too unless the section in question
 258                          * is the first in its containing segment.
 259                          */
 260                         dl = lma - s->lma;
 261                         for (i = 0; i < s->seg->nsec; i++)
 262                                 if (s->seg->v_sec[i] == s)
 263                                         break;
 264                         if (i >= s->seg->nsec)
 265                                 errx(EXIT_FAILURE, "Internal: section `%s' not"
 266                                     " found in its containing segement",
 267                                     s->name);
 268                         for (; i < s->seg->nsec; i++) {
 269                                 s0 = s->seg->v_sec[i];
 270                                 s0->lma += dl;
 271 #ifdef  DEBUG
 272                                 printf("section %s LMA set to %#jx\n",
 273                                     s0->name, (uintmax_t) s0->lma);
 274 #endif
 275                                 if (s != s->seg->v_sec[0]) {
 276                                         s0->off += dl;
 277 #ifdef  DEBUG
 278                                         printf("section %s offset set to %#jx\n",
 279                                             s0->name, (uintmax_t) s0->off);
 280 #endif
 281                                 }
 282                         }
 283                 }
 284         }
 285
 286         /*
 287          * Apply load address padding.
 288          */
 289
 290         if (ecp->pad_to != 0) {
 291
 292                 /*
 293                  * Find the section with highest load address.
 294                  */
 295
 296                 s = NULL;
 297                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 298                         if (seg->type != PT_LOAD)
 299                                 continue;
 300                         for (i = seg->nsec - 1; i >= 0; i--)
 301                                 if (seg->v_sec[i]->type != SHT_NOBITS)
 302                                         break;
 303                         if (i < 0)
 304                                 continue;
 305                         if (s == NULL)
 306                                 s = seg->v_sec[i];
 307                         else {
 308                                 s0 = seg->v_sec[i];
 309                                 if (s0->lma > s->lma)
 310                                         s = s0;
 311                         }
 312                 }
 313
 314                 if (s == NULL)
 315                         goto issue_warn;
 316
 317                 /* No need to pad if the pad_to address is lower. */
 318                 if (ecp->pad_to <= s->lma + s->sz)
 319                         goto issue_warn;
 320
 321                 s->pad_sz = ecp->pad_to - (s->lma + s->sz);
 322 #ifdef  DEBUG
 323                 printf("pad section %s load to address %#jx by %#jx\n", s->name,
 324                     (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz);
 325 #endif
 326         }
 327
 328 issue_warn:
 329
 330         /*
 331          * Issue a warning if there are VMA/LMA adjust requests for
 332          * some nonexistent sections.
 333          */
 334         if ((ecp->flags & NO_CHANGE_WARN) == 0) {
 335                 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) {
 336                         if (!sac->setvma && !sac->setlma &&
 337                             !sac->vma_adjust && !sac->lma_adjust)
 338                                 continue;
 339                         found = 0;
 340                         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 341                                 if (s->pseudo || s->name == NULL)
 342                                         continue;
 343                                 if (!strcmp(s->name, sac->name)) {
 344                                         found = 1;
 345                                         break;
 346                                 }
 347                         }
 348                         if (!found)
 349                                 warnx("cannot find section `%s'", sac->name);
 350                 }
 351         }
 352 }
 353
 354 static void
 355 insert_to_inseg_list(struct segment *seg, struct section *sec)
 356 {
 357         struct section *s;
 358         int i;
 359
 360         seg->nsec++;
 361         seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec));
 362         if (seg->v_sec == NULL)
 363                 err(EXIT_FAILURE, "realloc failed");
 364
 365         /*
 366          * Sort the section in order of offset.
 367          */
 368
 369         for (i = seg->nsec - 1; i > 0; i--) {
 370                 s = seg->v_sec[i - 1];
 371                 if (sec->off >= s->off) {
 372                         seg->v_sec[i] = sec;
 373                         break;
 374                 } else
 375                         seg->v_sec[i] = s;
 376         }
 377         if (i == 0)
 378                 seg->v_sec[0] = sec;
 379 }
 380
 381 void
 382 setup_phdr(struct elfcopy *ecp)
 383 {
 384         struct segment  *seg;
 385         GElf_Phdr        iphdr;
 386         size_t           iphnum;
 387         int              i;
 388
 389         if (elf_getphnum(ecp->ein, &iphnum) == 0)
 390                 errx(EXIT_FAILURE, "elf_getphnum failed: %s",
 391                     elf_errmsg(-1));
 392
 393         ecp->ophnum = ecp->iphnum = iphnum;
 394         if (iphnum == 0)
 395                 return;
 396
 397         /* If --only-keep-debug is specified, discard all program headers. */
 398         if (ecp->strip == STRIP_NONDEBUG) {
 399                 ecp->ophnum = 0;
 400                 return;
 401         }
 402
 403         for (i = 0; (size_t)i < iphnum; i++) {
 404                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 405                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 406                             elf_errmsg(-1));
 407                 if ((seg = calloc(1, sizeof(*seg))) == NULL)
 408                         err(EXIT_FAILURE, "calloc failed");
 409                 seg->addr       = iphdr.p_vaddr;
 410                 seg->off        = iphdr.p_offset;
 411                 seg->fsz        = iphdr.p_filesz;
 412                 seg->msz        = iphdr.p_memsz;
 413                 seg->type       = iphdr.p_type;
 414                 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list);
 415         }
 416 }
 417
 418 void
 419 copy_phdr(struct elfcopy *ecp)
 420 {
 421         struct segment  *seg;
 422         struct section  *s;
 423         GElf_Phdr        iphdr, ophdr;
 424         int              i;
 425
 426         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 427                 if (seg->type == PT_PHDR) {
 428                         if (!TAILQ_EMPTY(&ecp->v_sec)) {
 429                                 s = TAILQ_FIRST(&ecp->v_sec);
 430                                 if (s->pseudo)
 431                                         seg->addr = s->lma +
 432                                             gelf_fsize(ecp->eout, ELF_T_EHDR,
 433                                                 1, EV_CURRENT);
 434                         }
 435                         seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR,
 436                             ecp->ophnum, EV_CURRENT);
 437                         continue;
 438                 }
 439
 440                 seg->fsz = seg->msz = 0;
 441                 for (i = 0; i < seg->nsec; i++) {
 442                         s = seg->v_sec[i];
 443                         seg->msz = s->vma + s->sz - seg->addr;
 444                         if (s->type != SHT_NOBITS)
 445                                 seg->fsz = seg->msz;
 446                 }
 447         }
 448
 449         /*
 450          * Allocate space for program headers, note that libelf keep
 451          * track of the number in internal variable, and a call to
 452          * elf_update is needed to update e_phnum of ehdr.
 453          */
 454         if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL)
 455                 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s",
 456                     elf_errmsg(-1));
 457
 458         /*
 459          * This elf_update() call is to update the e_phnum field in
 460          * ehdr. It's necessary because later we will call gelf_getphdr(),
 461          * which does sanity check by comparing ndx argument with e_phnum.
 462          */
 463         if (elf_update(ecp->eout, ELF_C_NULL) < 0)
 464                 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1));
 465
 466         /*
 467          * iphnum == ophnum, since we don't remove program headers even if
 468          * they no longer contain sections.
 469          */
 470         i = 0;
 471         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 472                 if (i >= ecp->iphnum)
 473                         break;
 474                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 475                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 476                             elf_errmsg(-1));
 477                 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr)
 478                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 479                             elf_errmsg(-1));
 480
 481                 ophdr.p_type = iphdr.p_type;
 482                 ophdr.p_vaddr = seg->addr;
 483                 ophdr.p_paddr = seg->addr;
 484                 ophdr.p_flags = iphdr.p_flags;
 485                 ophdr.p_align = iphdr.p_align;
 486                 ophdr.p_offset = seg->off;
 487                 ophdr.p_filesz = seg->fsz;
 488                 ophdr.p_memsz = seg->msz;
 489                 if (!gelf_update_phdr(ecp->eout, i, &ophdr))
 490                         err(EXIT_FAILURE, "gelf_update_phdr failed :%s",
 491                             elf_errmsg(-1));
 492
 493                 i++;
 494         }
 495 }