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/cdefs.h>
  28 #include <sys/queue.h>
  29 #include <err.h>
  30 #include <gelf.h>
  31 #include <stdint.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include "elfcopy.h"
  37
  38 ELFTC_VCSID("$Id: segments.c 3134 2014-12-23 10:43:59Z kaiwang27 $");
  39
  40 static void     insert_to_inseg_list(struct segment *seg, struct section *sec);
  41
  42 /*
  43  * elfcopy's segment handling is relatively simpler and less powerful than
  44  * libbfd. Program headers are modified or copied from input to output objects,
  45  * but never re-generated. As a result, if the input object has incorrect
  46  * program headers, the output object's program headers will remain incorrect
  47  * or become even worse.
  48  */
  49
  50 /*
  51  * Check whether a section is "loadable". If so, add it to the
  52  * corresponding segment list(s) and return 1.
  53  */
  54 int
  55 add_to_inseg_list(struct elfcopy *ecp, struct section *s)
  56 {
  57         struct segment  *seg;
  58         int              loadable;
  59
  60         if (ecp->ophnum == 0)
  61                 return (0);
  62
  63         /*
  64          * Segment is a different view of an ELF object. One segment can
  65          * contain one or more sections, and one section can be included
  66          * in one or more segments, or not included in any segment at all.
  67          * We call those sections which can be found in one or more segments
  68          * "loadable" sections, and call the rest "unloadable" sections.
  69          * We keep track of "loadable" sections in their containing
  70          * segment(s)' v_sec queue. These information are later used to
  71          * recalculate the extents of segments, when sections are removed,
  72          * for example.
  73          */
  74         loadable = 0;
  75         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
  76                 if (s->off < seg->off || (s->vma < seg->addr && !s->pseudo))
  77                         continue;
  78                 if (s->off + s->sz > seg->off + seg->fsz &&
  79                     s->type != SHT_NOBITS)
  80                         continue;
  81                 if (s->off + s->sz > seg->off + seg->msz)
  82                         continue;
  83                 if (s->vma + s->sz > seg->addr + seg->msz)
  84                         continue;
  85
  86                 insert_to_inseg_list(seg, s);
  87                 if (seg->type == PT_LOAD)
  88                         s->seg = seg;
  89                 else if (seg->type == PT_TLS)
  90                         s->seg_tls = seg;
  91                 s->lma = seg->addr + (s->off - seg->off);
  92                 loadable = 1;
  93         }
  94
  95         return (loadable);
  96 }
  97
  98 void
  99 adjust_addr(struct elfcopy *ecp)
 100 {
 101         struct section *s, *s0;
 102         struct segment *seg;
 103         struct sec_action *sac;
 104         uint64_t dl, lma, start, end;
 105         int found, i;
 106
 107         /*
 108          * Apply VMA and global LMA changes in the first iteration.
 109          */
 110         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 111
 112                 /* Only adjust loadable section's address. */
 113                 if (!s->loadable || s->seg == NULL)
 114                         continue;
 115
 116                 /* Apply global LMA adjustment. */
 117                 if (ecp->change_addr != 0)
 118                         s->lma += ecp->change_addr;
 119
 120                 if (!s->pseudo) {
 121                         /* Apply global VMA adjustment. */
 122                         if (ecp->change_addr != 0)
 123                                 s->vma += ecp->change_addr;
 124
 125                         /* Apply section VMA adjustment. */
 126                         sac = lookup_sec_act(ecp, s->name, 0);
 127                         if (sac == NULL)
 128                                 continue;
 129                         if (sac->setvma)
 130                                 s->vma = sac->vma;
 131                         if (sac->vma_adjust != 0)
 132                                 s->vma += sac->vma_adjust;
 133                 }
 134         }
 135
 136         /*
 137          * Apply sections LMA change in the second iteration.
 138          */
 139         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 140
 141                 /* Only adjust loadable section's LMA. */
 142                 if (!s->loadable || s->seg == NULL)
 143                         continue;
 144
 145                 /*
 146                  * Check if there is a LMA change request for this
 147                  * section.
 148                  */
 149                 sac = lookup_sec_act(ecp, s->name, 0);
 150                 if (sac == NULL)
 151                         continue;
 152                 if (!sac->setlma && sac->lma_adjust == 0)
 153                         continue;
 154                 lma = s->lma;
 155                 if (sac->setlma)
 156                         lma = sac->lma;
 157                 if (sac->lma_adjust != 0)
 158                         lma += sac->lma_adjust;
 159                 if (lma == s->lma)
 160                         continue;
 161
 162                 /*
 163                  * Check if the LMA change is viable.
 164                  *
 165                  * 1. Check if the new LMA is properly aligned accroding to
 166                  *    section alignment.
 167                  *
 168                  * 2. Compute the new extent of segment that contains this
 169                  *    section, make sure it doesn't overlap with other
 170                  *    segments.
 171                  */
 172 #ifdef  DEBUG
 173                 printf("LMA for section %s: %#jx\n", s->name, lma);
 174 #endif
 175
 176                 if (lma % s->align != 0)
 177                         errx(EXIT_FAILURE, "The load address %#jx for "
 178                             "section %s is not aligned to %ju",
 179                             (uintmax_t) lma, s->name, s->align);
 180
 181                 if (lma < s->lma) {
 182                         /* Move section to lower address. */
 183                         if (lma < s->lma - s->seg->addr)
 184                                 errx(EXIT_FAILURE, "Not enough space to move "
 185                                     "section %s load address to %#jx", s->name,
 186                                     (uintmax_t) lma);
 187                         start = lma - (s->lma - s->seg->addr);
 188                         if (s == s->seg->v_sec[s->seg->nsec - 1])
 189                                 end = start + s->seg->msz;
 190                         else
 191                                 end = s->seg->addr + s->seg->msz;
 192
 193                 } else {
 194                         /* Move section to upper address. */
 195                         if (s == s->seg->v_sec[0])
 196                                 start = lma;
 197                         else
 198                                 start = s->seg->addr;
 199                         end = lma + (s->seg->addr + s->seg->msz - s->lma);
 200                         if (end < start)
 201                                 errx(EXIT_FAILURE, "Not enough space to move "
 202                                     "section %s load address to %#jx", s->name,
 203                                     (uintmax_t) lma);
 204                 }
 205
 206 #ifdef  DEBUG
 207                 printf("new extent for segment containing %s: (%#jx,%#jx)\n",
 208                     s->name, start, end);
 209 #endif
 210
 211                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 212                         if (seg == s->seg || seg->type != PT_LOAD)
 213                                 continue;
 214                         if (start > seg->addr + seg->msz)
 215                                 continue;
 216                         if (end < seg->addr)
 217                                 continue;
 218                         errx(EXIT_FAILURE, "The extent of segment containing "
 219                             "section %s overlaps with segment(%#jx,%#jx)",
 220                             s->name, seg->addr, seg->addr + seg->msz);
 221                 }
 222
 223                 /*
 224                  * Update section LMA and file offset.
 225                  */
 226
 227                 if (lma < s->lma) {
 228                         /*
 229                          * To move a section to lower load address, we decrease
 230                          * the load addresses of the section and all the
 231                          * sections that are before it, and we increase the
 232                          * file offsets of all the sections that are after it.
 233                          */
 234                         dl = s->lma - lma;
 235                         for (i = 0; i < s->seg->nsec; i++) {
 236                                 s0 = s->seg->v_sec[i];
 237                                 s0->lma -= dl;
 238 #ifdef  DEBUG
 239                                 printf("section %s LMA set to %#jx\n",
 240                                     s0->name, (uintmax_t) s0->lma);
 241 #endif
 242                                 if (s0 == s)
 243                                         break;
 244                         }
 245                         for (i = i + 1; i < s->seg->nsec; i++) {
 246                                 s0 = s->seg->v_sec[i];
 247                                 s0->off += dl;
 248 #ifdef  DEBUG
 249                                 printf("section %s offset set to %#jx\n",
 250                                     s0->name, (uintmax_t) s0->off);
 251 #endif
 252                         }
 253                 } else {
 254                         /*
 255                          * To move a section to upper load address, we increase
 256                          * the load addresses of the section and all the
 257                          * sections that are after it, and we increase the
 258                          * their file offsets too unless the section in question
 259                          * is the first in its containing segment.
 260                          */
 261                         dl = lma - s->lma;
 262                         for (i = 0; i < s->seg->nsec; i++)
 263                                 if (s->seg->v_sec[i] == s)
 264                                         break;
 265                         if (i >= s->seg->nsec)
 266                                 errx(EXIT_FAILURE, "Internal: section `%s' not"
 267                                     " found in its containing segement",
 268                                     s->name);
 269                         for (; i < s->seg->nsec; i++) {
 270                                 s0 = s->seg->v_sec[i];
 271                                 s0->lma += dl;
 272 #ifdef  DEBUG
 273                                 printf("section %s LMA set to %#jx\n",
 274                                     s0->name, (uintmax_t) s0->lma);
 275 #endif
 276                                 if (s != s->seg->v_sec[0]) {
 277                                         s0->off += dl;
 278 #ifdef  DEBUG
 279                                         printf("section %s offset set to %#jx\n",
 280                                             s0->name, (uintmax_t) s0->off);
 281 #endif
 282                                 }
 283                         }
 284                 }
 285         }
 286
 287         /*
 288          * Apply load address padding.
 289          */
 290
 291         if (ecp->pad_to != 0) {
 292
 293                 /*
 294                  * Find the section with highest load address.
 295                  */
 296
 297                 s = NULL;
 298                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 299                         if (seg->type != PT_LOAD)
 300                                 continue;
 301                         for (i = seg->nsec - 1; i >= 0; i--)
 302                                 if (seg->v_sec[i]->type != SHT_NOBITS)
 303                                         break;
 304                         if (i < 0)
 305                                 continue;
 306                         if (s == NULL)
 307                                 s = seg->v_sec[i];
 308                         else {
 309                                 s0 = seg->v_sec[i];
 310                                 if (s0->lma > s->lma)
 311                                         s = s0;
 312                         }
 313                 }
 314
 315                 if (s == NULL)
 316                         goto issue_warn;
 317
 318                 /* No need to pad if the pad_to address is lower. */
 319                 if (ecp->pad_to <= s->lma + s->sz)
 320                         goto issue_warn;
 321
 322                 s->pad_sz = ecp->pad_to - (s->lma + s->sz);
 323 #ifdef  DEBUG
 324                 printf("pad section %s load to address %#jx by %#jx\n", s->name,
 325                     (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz);
 326 #endif
 327         }
 328
 329 issue_warn:
 330
 331         /*
 332          * Issue a warning if there are VMA/LMA adjust requests for
 333          * some nonexistent sections.
 334          */
 335         if ((ecp->flags & NO_CHANGE_WARN) == 0) {
 336                 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) {
 337                         if (!sac->setvma && !sac->setlma &&
 338                             !sac->vma_adjust && !sac->lma_adjust)
 339                                 continue;
 340                         found = 0;
 341                         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 342                                 if (s->pseudo || s->name == NULL)
 343                                         continue;
 344                                 if (!strcmp(s->name, sac->name)) {
 345                                         found = 1;
 346                                         break;
 347                                 }
 348                         }
 349                         if (!found)
 350                                 warnx("cannot find section `%s'", sac->name);
 351                 }
 352         }
 353 }
 354
 355 static void
 356 insert_to_inseg_list(struct segment *seg, struct section *sec)
 357 {
 358         struct section *s;
 359         int i;
 360
 361         seg->nsec++;
 362         seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec));
 363         if (seg->v_sec == NULL)
 364                 err(EXIT_FAILURE, "realloc failed");
 365
 366         /*
 367          * Sort the section in order of offset.
 368          */
 369
 370         for (i = seg->nsec - 1; i > 0; i--) {
 371                 s = seg->v_sec[i - 1];
 372                 if (sec->off >= s->off) {
 373                         seg->v_sec[i] = sec;
 374                         break;
 375                 } else
 376                         seg->v_sec[i] = s;
 377         }
 378         if (i == 0)
 379                 seg->v_sec[0] = sec;
 380 }
 381
 382 void
 383 setup_phdr(struct elfcopy *ecp)
 384 {
 385         struct segment  *seg;
 386         GElf_Phdr        iphdr;
 387         size_t           iphnum;
 388         int              i;
 389
 390         if (elf_getphnum(ecp->ein, &iphnum) == 0)
 391                 errx(EXIT_FAILURE, "elf_getphnum failed: %s",
 392                     elf_errmsg(-1));
 393
 394         ecp->ophnum = ecp->iphnum = iphnum;
 395         if (iphnum == 0)
 396                 return;
 397
 398         /* If --only-keep-debug is specified, discard all program headers. */
 399         if (ecp->strip == STRIP_NONDEBUG) {
 400                 ecp->ophnum = 0;
 401                 return;
 402         }
 403
 404         for (i = 0; (size_t)i < iphnum; i++) {
 405                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 406                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 407                             elf_errmsg(-1));
 408                 if ((seg = calloc(1, sizeof(*seg))) == NULL)
 409                         err(EXIT_FAILURE, "calloc failed");
 410                 seg->addr       = iphdr.p_vaddr;
 411                 seg->off        = iphdr.p_offset;
 412                 seg->fsz        = iphdr.p_filesz;
 413                 seg->msz        = iphdr.p_memsz;
 414                 seg->type       = iphdr.p_type;
 415                 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list);
 416         }
 417 }
 418
 419 void
 420 copy_phdr(struct elfcopy *ecp)
 421 {
 422         struct segment  *seg;
 423         struct section  *s;
 424         GElf_Phdr        iphdr, ophdr;
 425         int              i;
 426
 427         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 428                 if (seg->type == PT_PHDR) {
 429                         if (!TAILQ_EMPTY(&ecp->v_sec)) {
 430                                 s = TAILQ_FIRST(&ecp->v_sec);
 431                                 if (s->pseudo)
 432                                         seg->addr = s->lma +
 433                                             gelf_fsize(ecp->eout, ELF_T_EHDR,
 434                                                 1, EV_CURRENT);
 435                         }
 436                         seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR,
 437                             ecp->ophnum, EV_CURRENT);
 438                         continue;
 439                 }
 440
 441                 seg->fsz = seg->msz = 0;
 442                 for (i = 0; i < seg->nsec; i++) {
 443                         s = seg->v_sec[i];
 444                         seg->msz = s->vma + s->sz - seg->addr;
 445                         if (s->type != SHT_NOBITS)
 446                                 seg->fsz = seg->msz;
 447                 }
 448         }
 449
 450         /*
 451          * Allocate space for program headers, note that libelf keep
 452          * track of the number in internal variable, and a call to
 453          * elf_update is needed to update e_phnum of ehdr.
 454          */
 455         if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL)
 456                 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s",
 457                     elf_errmsg(-1));
 458
 459         /*
 460          * This elf_update() call is to update the e_phnum field in
 461          * ehdr. It's necessary because later we will call gelf_getphdr(),
 462          * which does sanity check by comparing ndx argument with e_phnum.
 463          */
 464         if (elf_update(ecp->eout, ELF_C_NULL) < 0)
 465                 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1));
 466
 467         /*
 468          * iphnum == ophnum, since we don't remove program headers even if
 469          * they no longer contain sections.
 470          */
 471         i = 0;
 472         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 473                 if (i >= ecp->iphnum)
 474                         break;
 475                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 476                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 477                             elf_errmsg(-1));
 478                 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr)
 479                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 480                             elf_errmsg(-1));
 481
 482                 ophdr.p_type = iphdr.p_type;
 483                 ophdr.p_vaddr = seg->addr;
 484                 ophdr.p_paddr = seg->addr;
 485                 ophdr.p_flags = iphdr.p_flags;
 486                 ophdr.p_align = iphdr.p_align;
 487                 ophdr.p_offset = seg->off;
 488                 ophdr.p_filesz = seg->fsz;
 489                 ophdr.p_memsz = seg->msz;
 490                 if (!gelf_update_phdr(ecp->eout, i, &ophdr))
 491                         err(EXIT_FAILURE, "gelf_update_phdr failed :%s",
 492                             elf_errmsg(-1));
 493
 494                 i++;
 495         }
 496 }