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 2542 2012-08-12 16:14:15Z 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)
  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
  84                 insert_to_inseg_list(seg, s);
  85                 if (seg->type == PT_LOAD)
  86                         s->seg = seg;
  87                 s->lma = seg->addr + (s->off - seg->off);
  88                 loadable = 1;
  89         }
  90
  91         return (loadable);
  92 }
  93
  94 void
  95 adjust_addr(struct elfcopy *ecp)
  96 {
  97         struct section *s, *s0;
  98         struct segment *seg;
  99         struct sec_action *sac;
 100         uint64_t dl, lma, old_vma, start, end;
 101         int found, i;
 102
 103         /*
 104          * Apply VMA and global LMA changes in the first iteration.
 105          */
 106         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 107
 108                 /* Only adjust loadable section's address. */
 109                 if (!s->loadable || s->seg == NULL)
 110                         continue;
 111
 112                 /* Apply global LMA adjustment. */
 113                 if (ecp->change_addr != 0)
 114                         s->lma += ecp->change_addr;
 115
 116                 if (!s->pseudo) {
 117                         old_vma = s->vma;
 118
 119                         /* Apply global VMA adjustment. */
 120                         if (ecp->change_addr != 0)
 121                                 s->vma += ecp->change_addr;
 122
 123                         /* Apply section VMA adjustment. */
 124                         sac = lookup_sec_act(ecp, s->name, 0);
 125                         if (sac == NULL)
 126                                 continue;
 127                         if (sac->setvma)
 128                                 s->vma = sac->vma;
 129                         if (sac->vma_adjust != 0)
 130                                 s->vma += sac->vma_adjust;
 131                 }
 132         }
 133
 134         /*
 135          * Apply sections LMA change in the second iteration.
 136          */
 137         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 138
 139                 /* Only adjust loadable section's LMA. */
 140                 if (!s->loadable || s->seg == NULL)
 141                         continue;
 142
 143                 /*
 144                  * Check if there is a LMA change request for this
 145                  * section.
 146                  */
 147                 sac = lookup_sec_act(ecp, s->name, 0);
 148                 if (sac == NULL)
 149                         continue;
 150                 if (!sac->setlma && sac->lma_adjust == 0)
 151                         continue;
 152                 lma = s->lma;
 153                 if (sac->setlma)
 154                         lma = sac->lma;
 155                 if (sac->lma_adjust != 0)
 156                         lma += sac->lma_adjust;
 157                 if (lma == s->lma)
 158                         continue;
 159
 160                 /*
 161                  * Check if the LMA change is viable.
 162                  *
 163                  * 1. Check if the new LMA is properly aligned accroding to
 164                  *    section alignment.
 165                  *
 166                  * 2. Compute the new extent of segment that contains this
 167                  *    section, make sure it doesn't overlap with other
 168                  *    segments.
 169                  */
 170 #ifdef  DEBUG
 171                 printf("LMA for section %s: %#jx\n", s->name, lma);
 172 #endif
 173
 174                 if (lma % s->align != 0)
 175                         errx(EXIT_FAILURE, "The load address %#jx for "
 176                             "section %s is not aligned to %ju",
 177                             (uintmax_t) lma, s->name, s->align);
 178
 179                 if (lma < s->lma) {
 180                         /* Move section to lower address. */
 181                         if (lma < s->lma - s->seg->addr)
 182                                 errx(EXIT_FAILURE, "Not enough space to move "
 183                                     "section %s load address to %#jx", s->name,
 184                                     (uintmax_t) lma);
 185                         start = lma - (s->lma - s->seg->addr);
 186                         if (s == s->seg->v_sec[s->seg->nsec - 1])
 187                                 end = start + s->seg->msz;
 188                         else
 189                                 end = s->seg->addr + s->seg->msz;
 190
 191                 } else {
 192                         /* Move section to upper address. */
 193                         if (s == s->seg->v_sec[0])
 194                                 start = lma;
 195                         else
 196                                 start = s->seg->addr;
 197                         end = lma + (s->seg->addr + s->seg->msz - s->lma);
 198                         if (end < start)
 199                                 errx(EXIT_FAILURE, "Not enough space to move "
 200                                     "section %s load address to %#jx", s->name,
 201                                     (uintmax_t) lma);
 202                 }
 203
 204 #ifdef  DEBUG
 205                 printf("new extent for segment containing %s: (%#jx,%#jx)\n",
 206                     s->name, start, end);
 207 #endif
 208
 209                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 210                         if (seg == s->seg || seg->type != PT_LOAD)
 211                                 continue;
 212                         if (start > seg->addr + seg->msz)
 213                                 continue;
 214                         if (end < seg->addr)
 215                                 continue;
 216                         errx(EXIT_FAILURE, "The extent of segment containing "
 217                             "section %s overlaps with segment(%#jx,%#jx)",
 218                             s->name, seg->addr, seg->addr + seg->msz);
 219                 }
 220
 221                 /*
 222                  * Update section LMA and file offset.
 223                  */
 224
 225                 if (lma < s->lma) {
 226                         /*
 227                          * To move a section to lower load address, we decrease
 228                          * the load addresses of the section and all the
 229                          * sections that are before it, and we increase the
 230                          * file offsets of all the sections that are after it.
 231                          */
 232                         dl = s->lma - lma;
 233                         for (i = 0; i < s->seg->nsec; i++) {
 234                                 s0 = s->seg->v_sec[i];
 235                                 s0->lma -= dl;
 236 #ifdef  DEBUG
 237                                 printf("section %s LMA set to %#jx\n",
 238                                     s0->name, (uintmax_t) s0->lma);
 239 #endif
 240                                 if (s0 == s)
 241                                         break;
 242                         }
 243                         for (i = i + 1; i < s->seg->nsec; i++) {
 244                                 s0 = s->seg->v_sec[i];
 245                                 s0->off += dl;
 246 #ifdef  DEBUG
 247                                 printf("section %s offset set to %#jx\n",
 248                                     s0->name, (uintmax_t) s0->off);
 249 #endif
 250                         }
 251                 } else {
 252                         /*
 253                          * To move a section to upper load address, we increase
 254                          * the load addresses of the section and all the
 255                          * sections that are after it, and we increase the
 256                          * their file offsets too unless the section in question
 257                          * is the first in its containing segment.
 258                          */
 259                         dl = lma - s->lma;
 260                         for (i = 0; i < s->seg->nsec; i++)
 261                                 if (s->seg->v_sec[i] == s)
 262                                         break;
 263                         if (i >= s->seg->nsec)
 264                                 errx(EXIT_FAILURE, "Internal: section `%s' not"
 265                                     " found in its containing segement",
 266                                     s->name);
 267                         for (; i < s->seg->nsec; i++) {
 268                                 s0 = s->seg->v_sec[i];
 269                                 s0->lma += dl;
 270 #ifdef  DEBUG
 271                                 printf("section %s LMA set to %#jx\n",
 272                                     s0->name, (uintmax_t) s0->lma);
 273 #endif
 274                                 if (s != s->seg->v_sec[0]) {
 275                                         s0->off += dl;
 276 #ifdef  DEBUG
 277                                         printf("section %s offset set to %#jx\n",
 278                                             s0->name, (uintmax_t) s0->off);
 279 #endif
 280                                 }
 281                         }
 282                 }
 283         }
 284
 285         /*
 286          * Apply load address padding.
 287          */
 288
 289         if (ecp->pad_to != 0) {
 290
 291                 /*
 292                  * Find the section with highest load address.
 293                  */
 294
 295                 s = NULL;
 296                 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 297                         if (seg->type != PT_LOAD)
 298                                 continue;
 299                         for (i = seg->nsec - 1; i >= 0; i--)
 300                                 if (seg->v_sec[i]->type != SHT_NOBITS)
 301                                         break;
 302                         if (i < 0)
 303                                 continue;
 304                         if (s == NULL)
 305                                 s = seg->v_sec[i];
 306                         else {
 307                                 s0 = seg->v_sec[i];
 308                                 if (s0->lma > s->lma)
 309                                         s = s0;
 310                         }
 311                 }
 312
 313                 if (s == NULL)
 314                         goto issue_warn;
 315
 316                 /* No need to pad if the pad_to address is lower. */
 317                 if (ecp->pad_to <= s->lma + s->sz)
 318                         goto issue_warn;
 319
 320                 s->pad_sz = ecp->pad_to - (s->lma + s->sz);
 321 #ifdef  DEBUG
 322                 printf("pad section %s load to address %#jx by %#jx\n", s->name,
 323                     (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz);
 324 #endif
 325         }
 326
 327 issue_warn:
 328
 329         /*
 330          * Issue a warning if there are VMA/LMA adjust requests for
 331          * some nonexistent sections.
 332          */
 333         if ((ecp->flags & NO_CHANGE_WARN) == 0) {
 334                 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) {
 335                         if (!sac->setvma && !sac->setlma &&
 336                             !sac->vma_adjust && !sac->lma_adjust)
 337                                 continue;
 338                         found = 0;
 339                         TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
 340                                 if (s->pseudo || s->name == NULL)
 341                                         continue;
 342                                 if (!strcmp(s->name, sac->name)) {
 343                                         found = 1;
 344                                         break;
 345                                 }
 346                         }
 347                         if (!found)
 348                                 warnx("cannot find section `%s'", sac->name);
 349                 }
 350         }
 351 }
 352
 353 static void
 354 insert_to_inseg_list(struct segment *seg, struct section *sec)
 355 {
 356         struct section *s;
 357         int i;
 358
 359         seg->nsec++;
 360         seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec));
 361         if (seg->v_sec == NULL)
 362                 err(EXIT_FAILURE, "realloc failed");
 363
 364         /*
 365          * Sort the section in order of offset.
 366          */
 367
 368         for (i = seg->nsec - 1; i > 0; i--) {
 369                 s = seg->v_sec[i - 1];
 370                 if (sec->off >= s->off) {
 371                         seg->v_sec[i] = sec;
 372                         break;
 373                 } else
 374                         seg->v_sec[i] = s;
 375         }
 376         if (i == 0)
 377                 seg->v_sec[0] = sec;
 378 }
 379
 380 void
 381 setup_phdr(struct elfcopy *ecp)
 382 {
 383         struct segment  *seg;
 384         GElf_Phdr        iphdr;
 385         size_t           iphnum;
 386         int              i;
 387
 388         if (elf_getphnum(ecp->ein, &iphnum) == 0)
 389                 errx(EXIT_FAILURE, "elf_getphnum failed: %s",
 390                     elf_errmsg(-1));
 391
 392         ecp->ophnum = ecp->iphnum = iphnum;
 393         if (iphnum == 0)
 394                 return;
 395
 396         /* If --only-keep-debug is specified, discard all program headers. */
 397         if (ecp->strip == STRIP_NONDEBUG) {
 398                 ecp->ophnum = 0;
 399                 return;
 400         }
 401
 402         for (i = 0; (size_t)i < iphnum; i++) {
 403                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 404                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 405                             elf_errmsg(-1));
 406                 if ((seg = calloc(1, sizeof(*seg))) == NULL)
 407                         err(EXIT_FAILURE, "calloc failed");
 408                 seg->addr       = iphdr.p_vaddr;
 409                 seg->off        = iphdr.p_offset;
 410                 seg->fsz        = iphdr.p_filesz;
 411                 seg->msz        = iphdr.p_memsz;
 412                 seg->type       = iphdr.p_type;
 413                 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list);
 414         }
 415 }
 416
 417 void
 418 copy_phdr(struct elfcopy *ecp)
 419 {
 420         struct segment  *seg;
 421         struct section  *s;
 422         GElf_Phdr        iphdr, ophdr;
 423         int              i;
 424
 425         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 426                 if (seg->type == PT_PHDR) {
 427                         if (!TAILQ_EMPTY(&ecp->v_sec)) {
 428                                 s = TAILQ_FIRST(&ecp->v_sec);
 429                                 if (s->pseudo)
 430                                         seg->addr = s->lma +
 431                                             gelf_fsize(ecp->eout, ELF_T_EHDR,
 432                                                 1, EV_CURRENT);
 433                         }
 434                         seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR,
 435                             ecp->ophnum, EV_CURRENT);
 436                         continue;
 437                 }
 438
 439                 seg->fsz = seg->msz = 0;
 440                 for (i = 0; i < seg->nsec; i++) {
 441                         s = seg->v_sec[i];
 442                         seg->msz = s->vma + s->sz - seg->addr;
 443                         if (s->type != SHT_NOBITS)
 444                                 seg->fsz = seg->msz;
 445                 }
 446         }
 447
 448         /*
 449          * Allocate space for program headers, note that libelf keep
 450          * track of the number in internal variable, and a call to
 451          * elf_update is needed to update e_phnum of ehdr.
 452          */
 453         if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL)
 454                 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s",
 455                     elf_errmsg(-1));
 456
 457         /*
 458          * This elf_update() call is to update the e_phnum field in
 459          * ehdr. It's necessary because later we will call gelf_getphdr(),
 460          * which does sanity check by comparing ndx argument with e_phnum.
 461          */
 462         if (elf_update(ecp->eout, ELF_C_NULL) < 0)
 463                 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1));
 464
 465         /*
 466          * iphnum == ophnum, since we don't remove program headers even if
 467          * they no longer contain sections.
 468          */
 469         i = 0;
 470         STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) {
 471                 if (i >= ecp->iphnum)
 472                         break;
 473                 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr)
 474                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 475                             elf_errmsg(-1));
 476                 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr)
 477                         errx(EXIT_FAILURE, "gelf_getphdr failed: %s",
 478                             elf_errmsg(-1));
 479
 480                 ophdr.p_type = iphdr.p_type;
 481                 ophdr.p_vaddr = seg->addr;
 482                 ophdr.p_paddr = seg->addr;
 483                 ophdr.p_flags = iphdr.p_flags;
 484                 ophdr.p_align = iphdr.p_align;
 485                 ophdr.p_offset = seg->off;
 486                 ophdr.p_filesz = seg->fsz;
 487                 ophdr.p_memsz = seg->msz;
 488                 if (!gelf_update_phdr(ecp->eout, i, &ophdr))
 489                         err(EXIT_FAILURE, "gelf_update_phdr failed :%s",
 490                             elf_errmsg(-1));
 491
 492                 i++;
 493         }
 494 }