gdb/gcore.c

   1 /* Generate a core file for the inferior process.
   2
   3    Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program 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 of the License, or
  10    (at your option) any later version.
  11
  12    This program 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 this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "defs.h"
  23 #include "elf-bfd.h"
  24 #include "infcall.h"
  25 #include "inferior.h"
  26 #include "gdbcore.h"
  27 #include "objfiles.h"
  28 #include "symfile.h"
  29
  30 #include "cli/cli-decode.h"
  31
  32 #include "gdb_assert.h"
  33
  34 static char *default_gcore_target (void);
  35 static enum bfd_architecture default_gcore_arch (void);
  36 static unsigned long default_gcore_mach (void);
  37 static int gcore_memory_sections (bfd *);
  38
  39 /* Generate a core file from the inferior process.  */
  40
  41 static void
  42 gcore_command (char *args, int from_tty)
  43 {
  44   struct cleanup *old_chain;
  45   char *corefilename, corefilename_buffer[40];
  46   asection *note_sec = NULL;
  47   bfd *obfd;
  48   void *note_data = NULL;
  49   int note_size = 0;
  50
  51   /* No use generating a corefile without a target process.  */
  52   if (!target_has_execution)
  53     noprocess ();
  54
  55   if (args && *args)
  56     corefilename = args;
  57   else
  58     {
  59       /* Default corefile name is "core.PID".  */
  60       sprintf (corefilename_buffer, "core.%d", PIDGET (inferior_ptid));
  61       corefilename = corefilename_buffer;
  62     }
  63
  64   if (info_verbose)
  65     fprintf_filtered (gdb_stdout,
  66                       "Opening corefile '%s' for output.\n", corefilename);
  67
  68   /* Open the output file.  */
  69   obfd = bfd_openw (corefilename, default_gcore_target ());
  70   if (!obfd)
  71     error (_("Failed to open '%s' for output."), corefilename);
  72
  73   /* Need a cleanup that will close the file (FIXME: delete it?).  */
  74   old_chain = make_cleanup_bfd_close (obfd);
  75
  76   bfd_set_format (obfd, bfd_core);
  77   bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ());
  78
  79   /* An external target method must build the notes section.  */
  80   note_data = target_make_corefile_notes (obfd, &note_size);
  81
  82   /* Create the note section.  */
  83   if (note_data != NULL && note_size != 0)
  84     {
  85       note_sec = bfd_make_section_anyway (obfd, "note0");
  86       if (note_sec == NULL)
  87         error (_("Failed to create 'note' section for corefile: %s"),
  88                bfd_errmsg (bfd_get_error ()));
  89
  90       bfd_set_section_vma (obfd, note_sec, 0);
  91       bfd_set_section_flags (obfd, note_sec,
  92                              SEC_HAS_CONTENTS | SEC_READONLY | SEC_ALLOC);
  93       bfd_set_section_alignment (obfd, note_sec, 0);
  94       bfd_set_section_size (obfd, note_sec, note_size);
  95     }
  96
  97   /* Now create the memory/load sections.  */
  98   if (gcore_memory_sections (obfd) == 0)
  99     error (_("gcore: failed to get corefile memory sections from target."));
 100
 101   /* Write out the contents of the note section.  */
 102   if (note_data != NULL && note_size != 0)
 103     {
 104       if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size))
 105         warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
 106     }
 107
 108   /* Succeeded.  */
 109   fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename);
 110
 111   /* Clean-ups will close the output file and free malloc memory.  */
 112   do_cleanups (old_chain);
 113   return;
 114 }
 115
 116 static unsigned long
 117 default_gcore_mach (void)
 118 {
 119 #if 1   /* See if this even matters...  */
 120   return 0;
 121 #else
 122 #ifdef TARGET_ARCHITECTURE
 123   const struct bfd_arch_info *bfdarch = TARGET_ARCHITECTURE;
 124
 125   if (bfdarch != NULL)
 126     return bfdarch->mach;
 127 #endif /* TARGET_ARCHITECTURE */
 128   if (exec_bfd == NULL)
 129     error (_("Can't find default bfd machine type (need execfile)."));
 130
 131   return bfd_get_mach (exec_bfd);
 132 #endif /* 1 */
 133 }
 134
 135 static enum bfd_architecture
 136 default_gcore_arch (void)
 137 {
 138 #ifdef TARGET_ARCHITECTURE
 139   const struct bfd_arch_info * bfdarch = TARGET_ARCHITECTURE;
 140
 141   if (bfdarch != NULL)
 142     return bfdarch->arch;
 143 #endif
 144   if (exec_bfd == NULL)
 145     error (_("Can't find bfd architecture for corefile (need execfile)."));
 146
 147   return bfd_get_arch (exec_bfd);
 148 }
 149
 150 static char *
 151 default_gcore_target (void)
 152 {
 153   /* FIXME: This may only work for ELF targets.  */
 154   if (exec_bfd == NULL)
 155     return NULL;
 156   else
 157     return bfd_get_target (exec_bfd);
 158 }
 159
 160 /* Derive a reasonable stack segment by unwinding the target stack,
 161    and store its limits in *BOTTOM and *TOP.  Return non-zero if
 162    successful.  */
 163
 164 static int
 165 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
 166 {
 167   struct frame_info *fi, *tmp_fi;
 168
 169   gdb_assert (bottom);
 170   gdb_assert (top);
 171
 172   /* Can't succeed without stack and registers.  */
 173   if (!target_has_stack || !target_has_registers)
 174     return 0;
 175
 176   /* Can't succeed without current frame.  */
 177   fi = get_current_frame ();
 178   if (fi == NULL)
 179     return 0;
 180
 181   /* Save frame pointer of TOS frame.  */
 182   *top = get_frame_base (fi);
 183   /* If current stack pointer is more "inner", use that instead.  */
 184   if (INNER_THAN (read_sp (), *top))
 185     *top = read_sp ();
 186
 187   /* Find prev-most frame.  */
 188   while ((tmp_fi = get_prev_frame (fi)) != NULL)
 189     fi = tmp_fi;
 190
 191   /* Save frame pointer of prev-most frame.  */
 192   *bottom = get_frame_base (fi);
 193
 194   /* Now canonicalize their order, so that BOTTOM is a lower address
 195      (as opposed to a lower stack frame).  */
 196   if (*bottom > *top)
 197     {
 198       bfd_vma tmp_vma;
 199
 200       tmp_vma = *top;
 201       *top = *bottom;
 202       *bottom = tmp_vma;
 203     }
 204
 205   return 1;
 206 }
 207
 208 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
 209    the static data sections.  Store its limits in *BOTTOM and *TOP.
 210    Return non-zero if successful.  */
 211
 212 static int
 213 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
 214 {
 215   bfd_vma top_of_data_memory = 0;
 216   bfd_vma top_of_heap = 0;
 217   bfd_size_type sec_size;
 218   struct value *zero, *sbrk;
 219   bfd_vma sec_vaddr;
 220   asection *sec;
 221
 222   gdb_assert (bottom);
 223   gdb_assert (top);
 224
 225   /* This function depends on being able to call a function in the
 226      inferior.  */
 227   if (!target_has_execution)
 228     return 0;
 229
 230   /* The following code assumes that the link map is arranged as
 231      follows (low to high addresses):
 232
 233      ---------------------------------
 234      | text sections                 |
 235      ---------------------------------
 236      | data sections (including bss) |
 237      ---------------------------------
 238      | heap                          |
 239      --------------------------------- */
 240
 241   for (sec = abfd->sections; sec; sec = sec->next)
 242     {
 243       if (bfd_get_section_flags (abfd, sec) & SEC_DATA
 244           || strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
 245         {
 246           sec_vaddr = bfd_get_section_vma (abfd, sec);
 247           sec_size = bfd_get_section_size (sec);
 248           if (sec_vaddr + sec_size > top_of_data_memory)
 249             top_of_data_memory = sec_vaddr + sec_size;
 250         }
 251     }
 252
 253   /* Now get the top-of-heap by calling sbrk in the inferior.  */
 254   if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL)
 255     {
 256       sbrk = find_function_in_inferior ("sbrk");
 257       if (sbrk == NULL)
 258         return 0;
 259     }
 260   else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL)
 261     {
 262       sbrk = find_function_in_inferior ("_sbrk");
 263       if (sbrk == NULL)
 264         return 0;
 265     }
 266   else
 267     return 0;
 268
 269   zero = value_from_longest (builtin_type_int, 0);
 270   gdb_assert (zero);
 271   sbrk = call_function_by_hand (sbrk, 1, &zero);
 272   if (sbrk == NULL)
 273     return 0;
 274   top_of_heap = value_as_long (sbrk);
 275
 276   /* Return results.  */
 277   if (top_of_heap > top_of_data_memory)
 278     {
 279       *bottom = top_of_data_memory;
 280       *top = top_of_heap;
 281       return 1;
 282     }
 283
 284   /* No additional heap space needs to be saved.  */
 285   return 0;
 286 }
 287
 288 static void
 289 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
 290 {
 291   int p_flags = 0;
 292   int p_type;
 293
 294   /* FIXME: these constants may only be applicable for ELF.  */
 295   if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0)
 296     p_type = PT_LOAD;
 297   else
 298     p_type = PT_NOTE;
 299
 300   p_flags |= PF_R;      /* Segment is readable.  */
 301   if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
 302     p_flags |= PF_W;    /* Segment is writable.  */
 303   if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
 304     p_flags |= PF_X;    /* Segment is executable.  */
 305
 306   bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
 307 }
 308
 309 static int
 310 gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
 311                        int read, int write, int exec, void *data)
 312 {
 313   bfd *obfd = data;
 314   asection *osec;
 315   flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD;
 316
 317   /* If the memory segment has no permissions set, ignore it, otherwise
 318      when we later try to access it for read/write, we'll get an error
 319      or jam the kernel.  */
 320   if (read == 0 && write == 0 && exec == 0)
 321     {
 322       if (info_verbose)
 323         {
 324           fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at 0x%s\n",
 325                            paddr_d (size), paddr_nz (vaddr));
 326         }
 327
 328       return 0;
 329     }
 330
 331   if (write == 0)
 332     {
 333       /* See if this region of memory lies inside a known file on disk.
 334          If so, we can avoid copying its contents by clearing SEC_LOAD.  */
 335       struct objfile *objfile;
 336       struct obj_section *objsec;
 337
 338       ALL_OBJSECTIONS (objfile, objsec)
 339         {
 340           bfd *abfd = objfile->obfd;
 341           asection *asec = objsec->the_bfd_section;
 342           bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd,
 343                                                                     asec);
 344           bfd_vma start = objsec->addr & -align;
 345           bfd_vma end = (objsec->endaddr + align - 1) & -align;
 346           /* Match if either the entire memory region lies inside the
 347              section (i.e. a mapping covering some pages of a large
 348              segment) or the entire section lies inside the memory region
 349              (i.e. a mapping covering multiple small sections).
 350
 351              This BFD was synthesized from reading target memory,
 352              we don't want to omit that.  */
 353           if (((vaddr >= start && vaddr + size <= end)
 354                || (start >= vaddr && end <= vaddr + size))
 355               && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY))
 356             {
 357               flags &= ~SEC_LOAD;
 358               goto keep;        /* break out of two nested for loops */
 359             }
 360         }
 361
 362     keep:
 363       flags |= SEC_READONLY;
 364     }
 365
 366   if (exec)
 367     flags |= SEC_CODE;
 368   else
 369     flags |= SEC_DATA;
 370
 371   osec = bfd_make_section_anyway (obfd, "load");
 372   if (osec == NULL)
 373     {
 374       warning (_("Couldn't make gcore segment: %s"),
 375                bfd_errmsg (bfd_get_error ()));
 376       return 1;
 377     }
 378
 379   if (info_verbose)
 380     {
 381       fprintf_filtered (gdb_stdout, "Save segment, %s bytes at 0x%s\n",
 382                         paddr_d (size), paddr_nz (vaddr));
 383     }
 384
 385   bfd_set_section_size (obfd, osec, size);
 386   bfd_set_section_vma (obfd, osec, vaddr);
 387   bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma?  */
 388   bfd_set_section_flags (obfd, osec, flags);
 389   return 0;
 390 }
 391
 392 static int
 393 objfile_find_memory_regions (int (*func) (CORE_ADDR, unsigned long,
 394                                           int, int, int, void *),
 395                              void *obfd)
 396 {
 397   /* Use objfile data to create memory sections.  */
 398   struct objfile *objfile;
 399   struct obj_section *objsec;
 400   bfd_vma temp_bottom, temp_top;
 401
 402   /* Call callback function for each objfile section.  */
 403   ALL_OBJSECTIONS (objfile, objsec)
 404     {
 405       bfd *ibfd = objfile->obfd;
 406       asection *isec = objsec->the_bfd_section;
 407       flagword flags = bfd_get_section_flags (ibfd, isec);
 408       int ret;
 409
 410       if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
 411         {
 412           int size = bfd_section_size (ibfd, isec);
 413           int ret;
 414
 415           ret = (*func) (objsec->addr, bfd_section_size (ibfd, isec),
 416                          1, /* All sections will be readable.  */
 417                          (flags & SEC_READONLY) == 0, /* Writable.  */
 418                          (flags & SEC_CODE) != 0, /* Executable.  */
 419                          obfd);
 420           if (ret != 0)
 421             return ret;
 422         }
 423     }
 424
 425   /* Make a stack segment.  */
 426   if (derive_stack_segment (&temp_bottom, &temp_top))
 427     (*func) (temp_bottom, temp_top - temp_bottom,
 428              1, /* Stack section will be readable.  */
 429              1, /* Stack section will be writable.  */
 430              0, /* Stack section will not be executable.  */
 431              obfd);
 432
 433   /* Make a heap segment. */
 434   if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
 435     (*func) (temp_bottom, temp_top - temp_bottom,
 436              1, /* Heap section will be readable.  */
 437              1, /* Heap section will be writable.  */
 438              0, /* Heap section will not be executable.  */
 439              obfd);
 440
 441   return 0;
 442 }
 443
 444 static void
 445 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
 446 {
 447   bfd_size_type size = bfd_section_size (obfd, osec);
 448   struct cleanup *old_chain = NULL;
 449   void *memhunk;
 450
 451   /* Read-only sections are marked; we don't have to copy their contents.  */
 452   if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0)
 453     return;
 454
 455   /* Only interested in "load" sections.  */
 456   if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0)
 457     return;
 458
 459   memhunk = xmalloc (size);
 460   /* ??? This is crap since xmalloc should never return NULL.  */
 461   if (memhunk == NULL)
 462     error (_("Not enough memory to create corefile."));
 463   old_chain = make_cleanup (xfree, memhunk);
 464
 465   if (target_read_memory (bfd_section_vma (obfd, osec),
 466                           memhunk, size) != 0)
 467     warning (_("Memory read failed for corefile section, %s bytes at 0x%s."),
 468              paddr_d (size), paddr (bfd_section_vma (obfd, osec)));
 469   if (!bfd_set_section_contents (obfd, osec, memhunk, 0, size))
 470     warning (_("Failed to write corefile contents (%s)."),
 471              bfd_errmsg (bfd_get_error ()));
 472
 473   do_cleanups (old_chain);      /* Frees MEMHUNK.  */
 474 }
 475
 476 static int
 477 gcore_memory_sections (bfd *obfd)
 478 {
 479   if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
 480     return 0;                   /* FIXME: error return/msg?  */
 481
 482   /* Record phdrs for section-to-segment mapping.  */
 483   bfd_map_over_sections (obfd, make_output_phdrs, NULL);
 484
 485   /* Copy memory region contents.  */
 486   bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
 487
 488   return 1;
 489 }
 490
 491 void
 492 _initialize_gcore (void)
 493 {
 494   add_com ("generate-core-file", class_files, gcore_command, _("\
 495 Save a core file with the current state of the debugged process.\n\
 496 Argument is optional filename.  Default filename is 'core.<process_id>'."));
 497
 498   add_com_alias ("gcore", "generate-core-file", class_files, 1);
 499   exec_set_find_memory_regions (objfile_find_memory_regions);
 500 }