src/unexalpha.c

   1 /* Unexec for DEC alpha.  schoepf@sc.ZIB-Berlin.DE (Rainer Schoepf).
   2
   3    Copyright (C) 1994, 2000 Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 \f
  23 #include <config.h>
  24 #include <sys/types.h>
  25 #include <sys/file.h>
  26 #include <sys/stat.h>
  27 #include <sys/mman.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30 #ifdef HAVE_STRING_H
  31 #include <string.h>
  32 #endif
  33 #if !defined (__NetBSD__) && !defined (__OpenBSD__)
  34 #include <filehdr.h>
  35 #include <aouthdr.h>
  36 #include <scnhdr.h>
  37 #include <syms.h>
  38 #ifndef __linux__
  39 # include <reloc.h>
  40 # include <elf_abi.h>
  41 #endif
  42 #else /* __NetBSD__ or __OpenBSD__ */
  43 /*
  44  * NetBSD/Alpha does not have 'normal' user-land ECOFF support because
  45  * there's no desire to support ECOFF as the executable format in the
  46  * long term.
  47  */
  48 #include <sys/exec_ecoff.h>
  49
  50 /* Structures, constants, etc., that NetBSD defines strangely. */
  51 #define filehdr         ecoff_filehdr
  52 #define aouthdr         ecoff_aouthdr
  53 #define scnhdr          ecoff_scnhdr
  54 #define HDRR            struct ecoff_symhdr
  55 #define pHDRR           HDRR *
  56 #define cbHDRR          sizeof(HDRR)
  57 #ifdef __OpenBSD__
  58 #define ALPHAMAGIC      ECOFF_MAGIC_NATIVE_ALPHA
  59 #else
  60 #define ALPHAMAGIC      ECOFF_MAGIC_NETBSD_ALPHA
  61 #endif
  62 #define ZMAGIC          ECOFF_ZMAGIC
  63
  64 /* Misc. constants that NetBSD doesn't define at all. */
  65 #define ALPHAUMAGIC     0617
  66 #define _MIPS_NSCNS_MAX 35
  67 #define STYP_TEXT       0x00000020
  68 #define STYP_DATA       0x00000040
  69 #define STYP_BSS        0x00000080
  70 #define STYP_RDATA      0x00000100
  71 #define STYP_SDATA      0x00000200
  72 #define STYP_SBSS       0x00000400
  73 #define STYP_INIT       0x80000000
  74 #define _TEXT           ".text"
  75 #define _DATA           ".data"
  76 #define _BSS            ".bss"
  77 #define _INIT           ".init"
  78 #define _RDATA          ".rdata"
  79 #define _SDATA          ".sdata"
  80 #define _SBSS           ".sbss"
  81 #endif /* __NetBSD__ || __OpenBSD__ */
  82
  83 static void fatal_unexec __P ((char *, char *));
  84 static void mark_x __P ((char *));
  85
  86 static void update_dynamic_symbols __P ((char *, char *, int, struct aouthdr));
  87
  88 #define READ(_fd, _buffer, _size, _error_message, _error_arg) \
  89         errno = EEOF; \
  90         if (read (_fd, _buffer, _size) != _size) \
  91           fatal_unexec (_error_message, _error_arg);
  92
  93 #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \
  94         if (write (_fd, _buffer, _size) != _size) \
  95           fatal_unexec (_error_message, _error_arg);
  96
  97 #define SEEK(_fd, _position, _error_message, _error_arg) \
  98         errno = EEOF; \
  99         if (lseek (_fd, _position, L_SET) != _position) \
 100           fatal_unexec (_error_message, _error_arg);
 101
 102 #ifdef HAVE_UNISTD_H
 103 #include <unistd.h>
 104 #else
 105 void *sbrk ();
 106 #endif
 107
 108 #define EEOF -1
 109
 110 static struct scnhdr *text_section;
 111 static struct scnhdr *rel_dyn_section;
 112 static struct scnhdr *dynstr_section;
 113 static struct scnhdr *dynsym_section;
 114 static struct scnhdr *init_section;
 115 static struct scnhdr *finit_section;
 116 static struct scnhdr *rdata_section;
 117 static struct scnhdr *rconst_section;
 118 static struct scnhdr *data_section;
 119 static struct scnhdr *pdata_section;
 120 static struct scnhdr *xdata_section;
 121 static struct scnhdr *got_section;
 122 static struct scnhdr *lit8_section;
 123 static struct scnhdr *lit4_section;
 124 static struct scnhdr *sdata_section;
 125 static struct scnhdr *sbss_section;
 126 static struct scnhdr *bss_section;
 127
 128 static struct scnhdr old_data_scnhdr;
 129
 130 static unsigned long Brk;
 131
 132 struct headers {
 133     struct filehdr fhdr;
 134     struct aouthdr aout;
 135     struct scnhdr section[_MIPS_NSCNS_MAX];
 136 };
 137
 138
 139
 140 /* Define name of label for entry point for the dumped executable.  */
 141
 142 #ifndef DEFAULT_ENTRY_ADDRESS
 143 #define DEFAULT_ENTRY_ADDRESS __start
 144 #endif
 145 \f
 146 void
 147 unexec (new_name, a_name, data_start, bss_start, entry_address)
 148      char *new_name, *a_name;
 149      unsigned long data_start, bss_start, entry_address;
 150 {
 151   int new, old;
 152   char * oldptr;
 153   struct headers ohdr, nhdr;
 154   struct stat stat;
 155   long pagesize, brk;
 156   long newsyms, symrel;
 157   int nread;
 158   int i;
 159   long vaddr, scnptr;
 160 #define BUFSIZE 8192
 161   char buffer[BUFSIZE];
 162
 163   if ((old = open (a_name, O_RDONLY)) < 0)
 164     fatal_unexec ("opening %s", a_name);
 165
 166   new = creat (new_name, 0666);
 167   if (new < 0) fatal_unexec ("creating %s", new_name);
 168
 169   if ((fstat (old, &stat) == -1))
 170     fatal_unexec ("fstat %s", a_name);
 171
 172   oldptr = (char *)mmap (0, stat.st_size, PROT_READ, MAP_FILE|MAP_SHARED, old, 0);
 173
 174   if (oldptr == (char *)-1)
 175     fatal_unexec ("mmap %s", a_name);
 176
 177   close (old);
 178
 179   /* This is a copy of the a.out header of the original executable */
 180
 181   ohdr = (*(struct headers *)oldptr);
 182
 183   /* This is where we build the new header from the in-memory copy */
 184
 185   nhdr = *((struct headers *)TEXT_START);
 186
 187   /* First do some consistency checks */
 188
 189   if (nhdr.fhdr.f_magic != ALPHAMAGIC
 190       && nhdr.fhdr.f_magic != ALPHAUMAGIC)
 191     {
 192       fprintf (stderr, "unexec: input file magic number is %x, not %x or %x.\n",
 193                nhdr.fhdr.f_magic, ALPHAMAGIC, ALPHAUMAGIC);
 194       exit (1);
 195     }
 196
 197   if (nhdr.fhdr.f_opthdr != sizeof (nhdr.aout))
 198     {
 199       fprintf (stderr, "unexec: input a.out header is %d bytes, not %d.\n",
 200                nhdr.fhdr.f_opthdr, (int)sizeof (nhdr.aout));
 201       exit (1);
 202     }
 203   if (nhdr.aout.magic != ZMAGIC)
 204     {
 205       fprintf (stderr, "unexec: input file a.out magic number is %o, not %o.\n",
 206                nhdr.aout.magic, ZMAGIC);
 207       exit (1);
 208     }
 209
 210
 211   /* Now check the existence of certain header section and grab
 212      their addresses. */
 213
 214 #define CHECK_SCNHDR(ptr, name, flags)                                  \
 215   ptr = NULL;                                                           \
 216   for (i = 0; i < nhdr.fhdr.f_nscns && !ptr; i++)                       \
 217     if (strncmp (nhdr.section[i].s_name, name, 8) == 0)                 \
 218       {                                                                 \
 219         if (nhdr.section[i].s_flags != flags)                           \
 220           fprintf (stderr, "unexec: %x flags (%x expected) in %s section.\n", \
 221                    nhdr.section[i].s_flags, flags, name);               \
 222         ptr = nhdr.section + i;                                         \
 223       }                                                                 \
 224
 225   CHECK_SCNHDR (text_section,  _TEXT,  STYP_TEXT);
 226   CHECK_SCNHDR (init_section,  _INIT,  STYP_INIT);
 227 #ifdef _REL_DYN
 228   CHECK_SCNHDR (rel_dyn_section, _REL_DYN,  STYP_REL_DYN);
 229 #endif /* _REL_DYN */
 230 #ifdef _DYNSYM
 231   CHECK_SCNHDR (dynsym_section, _DYNSYM,  STYP_DYNSYM);
 232 #endif /* _REL_DYN */
 233 #ifdef _DYNSTR
 234   CHECK_SCNHDR (dynstr_section, _DYNSTR,  STYP_DYNSTR);
 235 #endif /* _REL_DYN */
 236 #ifdef _FINI
 237   CHECK_SCNHDR (finit_section, _FINI,  STYP_FINI);
 238 #endif /* _FINI */
 239   CHECK_SCNHDR (rdata_section, _RDATA, STYP_RDATA);
 240 #ifdef _RCONST
 241   CHECK_SCNHDR (rconst_section, _RCONST, STYP_RCONST);
 242 #endif
 243 #ifdef _PDATA
 244   CHECK_SCNHDR (pdata_section, _PDATA, STYP_PDATA);
 245 #endif /* _PDATA */
 246 #ifdef _GOT
 247   CHECK_SCNHDR (got_section,   _GOT,   STYP_GOT);
 248 #endif /* _GOT */
 249   CHECK_SCNHDR (data_section,  _DATA,  STYP_DATA);
 250 #ifdef _XDATA
 251   CHECK_SCNHDR (xdata_section, _XDATA, STYP_XDATA);
 252 #endif /* _XDATA */
 253 #ifdef _LIT8
 254   CHECK_SCNHDR (lit8_section,  _LIT8,  STYP_LIT8);
 255   CHECK_SCNHDR (lit4_section,  _LIT4,  STYP_LIT4);
 256 #endif /* _LIT8 */
 257   CHECK_SCNHDR (sdata_section, _SDATA, STYP_SDATA);
 258   CHECK_SCNHDR (sbss_section,  _SBSS,  STYP_SBSS);
 259   CHECK_SCNHDR (bss_section,   _BSS,   STYP_BSS);
 260
 261
 262   pagesize = getpagesize ();
 263   brk = (((long) (sbrk (0))) + pagesize - 1) & (-pagesize);
 264
 265   /* Remember the current break */
 266
 267   Brk = brk;
 268
 269   bcopy (data_section, &old_data_scnhdr, sizeof (old_data_scnhdr));
 270
 271   nhdr.aout.dsize = brk - DATA_START;
 272   nhdr.aout.bsize = 0;
 273   if (entry_address == 0)
 274     {
 275       extern DEFAULT_ENTRY_ADDRESS ();
 276       nhdr.aout.entry = (unsigned long)DEFAULT_ENTRY_ADDRESS;
 277     }
 278   else
 279     nhdr.aout.entry = entry_address;
 280
 281   nhdr.aout.bss_start = nhdr.aout.data_start + nhdr.aout.dsize;
 282
 283   if (rdata_section != NULL)
 284     {
 285       rdata_section->s_size = data_start - DATA_START;
 286
 287       /* Adjust start and virtual addresses of rdata_section, too.  */
 288       rdata_section->s_vaddr = DATA_START;
 289       rdata_section->s_paddr = DATA_START;
 290       rdata_section->s_scnptr = text_section->s_scnptr + nhdr.aout.tsize;
 291     }
 292
 293   data_section->s_vaddr = data_start;
 294   data_section->s_paddr = data_start;
 295   data_section->s_size = brk - data_start;
 296
 297   if (rdata_section != NULL)
 298     {
 299       data_section->s_scnptr = rdata_section->s_scnptr + rdata_section->s_size;
 300     }
 301
 302   vaddr = data_section->s_vaddr + data_section->s_size;
 303   scnptr = data_section->s_scnptr + data_section->s_size;
 304   if (lit8_section != NULL)
 305     {
 306       lit8_section->s_vaddr = vaddr;
 307       lit8_section->s_paddr = vaddr;
 308       lit8_section->s_size = 0;
 309       lit8_section->s_scnptr = scnptr;
 310     }
 311   if (lit4_section != NULL)
 312     {
 313       lit4_section->s_vaddr = vaddr;
 314       lit4_section->s_paddr = vaddr;
 315       lit4_section->s_size = 0;
 316       lit4_section->s_scnptr = scnptr;
 317     }
 318   if (sdata_section != NULL)
 319     {
 320       sdata_section->s_vaddr = vaddr;
 321       sdata_section->s_paddr = vaddr;
 322       sdata_section->s_size = 0;
 323       sdata_section->s_scnptr = scnptr;
 324     }
 325 #ifdef _XDATA
 326   if (xdata_section != NULL)
 327     {
 328       xdata_section->s_vaddr = vaddr;
 329       xdata_section->s_paddr = vaddr;
 330       xdata_section->s_size = 0;
 331       xdata_section->s_scnptr = scnptr;
 332     }
 333 #endif
 334 #ifdef _GOT
 335   if (got_section != NULL)
 336     {
 337       bcopy (got_section, buffer, sizeof (struct scnhdr));
 338
 339       got_section->s_vaddr = vaddr;
 340       got_section->s_paddr = vaddr;
 341       got_section->s_size = 0;
 342       got_section->s_scnptr = scnptr;
 343     }
 344 #endif /*_GOT */
 345   if (sbss_section != NULL)
 346     {
 347       sbss_section->s_vaddr = vaddr;
 348       sbss_section->s_paddr = vaddr;
 349       sbss_section->s_size = 0;
 350       sbss_section->s_scnptr = scnptr;
 351     }
 352   if (bss_section != NULL)
 353     {
 354       bss_section->s_vaddr = vaddr;
 355       bss_section->s_paddr = vaddr;
 356       bss_section->s_size = 0;
 357       bss_section->s_scnptr = scnptr;
 358     }
 359
 360   WRITE (new, (char *)TEXT_START, nhdr.aout.tsize,
 361          "writing text section to %s", new_name);
 362   WRITE (new, (char *)DATA_START, nhdr.aout.dsize,
 363          "writing data section to %s", new_name);
 364
 365 #ifdef _GOT
 366 #define old_got_section ((struct scnhdr *)buffer)
 367
 368   if (got_section != NULL)
 369     {
 370       SEEK (new, old_got_section->s_scnptr,
 371             "seeking to start of got_section in %s", new_name);
 372       WRITE (new, oldptr + old_got_section->s_scnptr, old_got_section->s_size,
 373              "writing new got_section of %s", new_name);
 374       SEEK (new, nhdr.aout.tsize + nhdr.aout.dsize,
 375             "seeking to end of data section of %s", new_name);
 376     }
 377
 378 #undef old_got_section
 379 #endif
 380
 381   /*
 382    * Construct new symbol table header
 383    */
 384
 385   bcopy (oldptr + nhdr.fhdr.f_symptr, buffer, cbHDRR);
 386
 387 #define symhdr ((pHDRR)buffer)
 388   newsyms = nhdr.aout.tsize + nhdr.aout.dsize;
 389   symrel = newsyms - nhdr.fhdr.f_symptr;
 390   nhdr.fhdr.f_symptr = newsyms;
 391   symhdr->cbLineOffset += symrel;
 392   symhdr->cbDnOffset += symrel;
 393   symhdr->cbPdOffset += symrel;
 394   symhdr->cbSymOffset += symrel;
 395   symhdr->cbOptOffset += symrel;
 396   symhdr->cbAuxOffset += symrel;
 397   symhdr->cbSsOffset += symrel;
 398   symhdr->cbSsExtOffset += symrel;
 399   symhdr->cbFdOffset += symrel;
 400   symhdr->cbRfdOffset += symrel;
 401   symhdr->cbExtOffset += symrel;
 402
 403   WRITE (new, buffer, cbHDRR, "writing symbol table header of %s", new_name);
 404
 405   /*
 406    * Copy the symbol table and line numbers
 407    */
 408   WRITE (new, oldptr + ohdr.fhdr.f_symptr + cbHDRR,
 409          stat.st_size - ohdr.fhdr.f_symptr - cbHDRR,
 410          "writing symbol table of %s", new_name);
 411
 412 #ifdef _REL_DYN
 413   if (rel_dyn_section)
 414     update_dynamic_symbols (oldptr, new_name, new, nhdr.aout);
 415 #endif
 416
 417 #undef symhdr
 418
 419   SEEK (new, 0, "seeking to start of header in %s", new_name);
 420   WRITE (new, &nhdr, sizeof (nhdr),
 421          "writing header of %s", new_name);
 422
 423   close (old);
 424   close (new);
 425   mark_x (new_name);
 426 }
 427
 428
 429 static void
 430 update_dynamic_symbols (old, new_name, new, aout)
 431      char *old;                 /* Pointer to old executable */
 432      char *new_name;            /* Name of new executable */
 433      int new;                   /* File descriptor for new executable */
 434      struct aouthdr aout;       /* a.out info from the file header */
 435 {
 436 #if !defined (__linux__) && !defined (__NetBSD__) && !defined (__OpenBSD__)
 437
 438   typedef struct dynrel_info {
 439     char * addr;
 440     unsigned type:8;
 441     unsigned index:24;
 442     unsigned info:8;
 443     unsigned pad:8;
 444   } dr_info;
 445
 446   int nsyms = rel_dyn_section->s_size / sizeof (struct dynrel_info);
 447   int i;
 448   dr_info * rd_base = (dr_info *) (old + rel_dyn_section->s_scnptr);
 449   Elf32_Sym * ds_base = (Elf32_Sym *) (old + dynsym_section->s_scnptr);
 450
 451   for (i = 0; i < nsyms; i++) {
 452     register Elf32_Sym x;
 453
 454     if (rd_base[i].index == 0)
 455       continue;
 456
 457     x = ds_base[rd_base[i].index];
 458
 459 #if 0
 460       fprintf (stderr, "Object inspected: %s, addr = %lx, shndx = %x",
 461                old + dynstr_section->s_scnptr + x.st_name, rd_base[i].addr, x.st_shndx);
 462 #endif
 463
 464
 465     if ((ELF32_ST_BIND (x.st_info) == STB_GLOBAL)
 466         && (x.st_shndx == 0)
 467         /* && (x.st_value == NULL) */
 468         ) {
 469       /* OK, this is probably a reference to an object in a shared
 470          library, so copy the old value. This is done in several steps:
 471          1. reladdr is the address of the location in question relative to
 472             the start of the data section,
 473          2. oldref is the addr is the mapped in temacs executable,
 474          3. newref is the address of the location in question in the
 475             undumped executable,
 476          4. len is the size of the object reference in bytes --
 477             currently only 4 (long) and 8 (quad) are supported.
 478             */
 479       register unsigned long reladdr = (long)rd_base[i].addr - old_data_scnhdr.s_vaddr;
 480       char * oldref = old + old_data_scnhdr.s_scnptr + reladdr;
 481       unsigned long newref = aout.tsize + reladdr;
 482       int len;
 483
 484 #if 0
 485       fprintf (stderr, "...relocated\n");
 486 #endif
 487
 488       if (rd_base[i].type == R_REFLONG)
 489         len = 4;
 490       else if (rd_base[i].type == R_REFQUAD)
 491         len = 8;
 492       else
 493         fatal_unexec ("unrecognized relocation type in .dyn.rel section (symbol #%d)", (char *) i);
 494
 495       SEEK (new, newref, "seeking to dynamic symbol in %s", new_name);
 496       WRITE (new, oldref, len, "writing old dynrel info in %s", new_name);
 497     }
 498
 499 #if 0
 500     else
 501       fprintf (stderr, "...not relocated\n");
 502 #endif
 503
 504   }
 505
 506 #endif /* not __linux__ and not __NetBSD__ and not __OpenBSD__ */
 507 }
 508
 509 \f
 510 /*
 511  * mark_x
 512  *
 513  * After successfully building the new a.out, mark it executable
 514  */
 515
 516 static void
 517 mark_x (name)
 518      char *name;
 519 {
 520   struct stat sbuf;
 521   int um = umask (777);
 522   umask (um);
 523   if (stat (name, &sbuf) < 0)
 524     fatal_unexec ("getting protection on %s", name);
 525   sbuf.st_mode |= 0111 & ~um;
 526   if (chmod (name, sbuf.st_mode) < 0)
 527     fatal_unexec ("setting protection on %s", name);
 528 }
 529
 530 static void
 531 fatal_unexec (s, arg)
 532      char *s;
 533      char *arg;
 534 {
 535   if (errno == EEOF)
 536     fputs ("unexec: unexpected end of file, ", stderr);
 537   else
 538     fprintf (stderr, "unexec: %s, ", strerror (errno));
 539   fprintf (stderr, s, arg);
 540   fputs (".\n", stderr);
 541   exit (1);
 542 }
 543
 544 /* arch-tag: 46316c49-ee08-4aa3-942b-00798902f5bd
 545    (do not change this comment) */