gdb/gcore.c

   1 /* Generate a core file for the inferior process.
   2
   3    Copyright 2001, 2002, 2003 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., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, 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_before_reloc (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 /* ARGSUSED */
 289 static void
 290 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
 291 {
 292   int p_flags = 0;
 293   int p_type;
 294
 295   /* FIXME: these constants may only be applicable for ELF.  */
 296   if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0)
 297     p_type = PT_LOAD;
 298   else
 299     p_type = PT_NOTE;
 300
 301   p_flags |= PF_R;      /* Segment is readable.  */
 302   if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
 303     p_flags |= PF_W;    /* Segment is writable.  */
 304   if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
 305     p_flags |= PF_X;    /* Segment is executable.  */
 306
 307   bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
 308 }
 309
 310 static asection *
 311 make_mem_sec (bfd *obfd, bfd_vma addr, bfd_size_type size,
 312               unsigned int flags, unsigned int alignment)
 313 {
 314   asection *osec;
 315
 316   osec = bfd_make_section_anyway (obfd, "load");
 317   if (osec == NULL)
 318     {
 319       warning ("Couldn't make gcore segment: %s",
 320                bfd_errmsg (bfd_get_error ()));
 321       return NULL;
 322     }
 323
 324   if (info_verbose)
 325     {
 326       fprintf_filtered (gdb_stdout, "Save segment, %lld bytes at 0x%s\n",
 327                         (long long) size, paddr_nz (addr));
 328     }
 329
 330   bfd_set_section_size (obfd, osec, size);
 331   bfd_set_section_vma (obfd, osec, addr);
 332   bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma?  */
 333   bfd_set_section_alignment (obfd, osec, alignment);
 334   bfd_set_section_flags (obfd, osec,
 335                          flags | SEC_LOAD | SEC_ALLOC | SEC_HAS_CONTENTS);
 336   return osec;
 337 }
 338
 339 static int
 340 gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
 341                        int read, int write, int exec, void *data)
 342 {
 343   flagword flags = 0;
 344
 345   if (write == 0)
 346     {
 347       flags |= SEC_READONLY;
 348       /* Mark readonly sections as zero-sized, such that we can avoid
 349          copying their contents.  */
 350       size = 0;
 351     }
 352
 353   if (exec)
 354     flags |= SEC_CODE;
 355   else
 356     flags |= SEC_DATA;
 357
 358   return ((make_mem_sec (data, vaddr, size, flags, 0)) == NULL);
 359 }
 360
 361 static int
 362 objfile_find_memory_regions (int (*func) (CORE_ADDR, unsigned long,
 363                                           int, int, int, void *),
 364                              void *obfd)
 365 {
 366   /* Use objfile data to create memory sections.  */
 367   struct objfile *objfile;
 368   struct obj_section *objsec;
 369   bfd_vma temp_bottom, temp_top;
 370
 371   /* Call callback function for each objfile section.  */
 372   ALL_OBJSECTIONS (objfile, objsec)
 373     {
 374       bfd *ibfd = objfile->obfd;
 375       asection *isec = objsec->the_bfd_section;
 376       flagword flags = bfd_get_section_flags (ibfd, isec);
 377       int ret;
 378
 379       if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
 380         {
 381           int size = bfd_section_size (ibfd, isec);
 382           int ret;
 383
 384           ret = (*func) (objsec->addr, bfd_section_size (ibfd, isec),
 385                          1, /* All sections will be readable.  */
 386                          (flags & SEC_READONLY) == 0, /* Writable.  */
 387                          (flags & SEC_CODE) != 0, /* Executable.  */
 388                          obfd);
 389           if (ret != 0)
 390             return ret;
 391         }
 392     }
 393
 394   /* Make a stack segment.  */
 395   if (derive_stack_segment (&temp_bottom, &temp_top))
 396     (*func) (temp_bottom, temp_top - temp_bottom,
 397              1, /* Stack section will be readable.  */
 398              1, /* Stack section will be writable.  */
 399              0, /* Stack section will not be executable.  */
 400              obfd);
 401
 402   /* Make a heap segment. */
 403   if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
 404     (*func) (temp_bottom, temp_top - temp_bottom,
 405              1, /* Heap section will be readable.  */
 406              1, /* Heap section will be writable.  */
 407              0, /* Heap section will not be executable.  */
 408              obfd);
 409
 410   return 0;
 411 }
 412
 413 static void
 414 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
 415 {
 416   bfd_size_type size = bfd_section_size (obfd, osec);
 417   struct cleanup *old_chain = NULL;
 418   void *memhunk;
 419
 420   /* Read-only sections are marked as zero-size.  We don't have to
 421      copy their contents.  */
 422   if (size == 0)
 423     return;
 424
 425   /* Only interested in "load" sections.  */
 426   if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0)
 427     return;
 428
 429   memhunk = xmalloc (size);
 430   /* ??? This is crap since xmalloc should never return NULL.  */
 431   if (memhunk == NULL)
 432     error ("Not enough memory to create corefile.");
 433   old_chain = make_cleanup (xfree, memhunk);
 434
 435   if (target_read_memory (bfd_section_vma (obfd, osec),
 436                           memhunk, size) != 0)
 437     warning ("Memory read failed for corefile section, %ld bytes at 0x%s\n",
 438              (long) size, paddr (bfd_section_vma (obfd, osec)));
 439   if (!bfd_set_section_contents (obfd, osec, memhunk, 0, size))
 440     warning ("Failed to write corefile contents (%s).",
 441              bfd_errmsg (bfd_get_error ()));
 442
 443   do_cleanups (old_chain);      /* Frees MEMHUNK.  */
 444 }
 445
 446 static int
 447 gcore_memory_sections (bfd *obfd)
 448 {
 449   if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
 450     return 0;                   /* FIXME: error return/msg?  */
 451
 452   /* Record phdrs for section-to-segment mapping.  */
 453   bfd_map_over_sections (obfd, make_output_phdrs, NULL);
 454
 455   /* Copy memory region contents.  */
 456   bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
 457
 458   return 1;
 459 }
 460
 461 void
 462 _initialize_gcore (void)
 463 {
 464   add_com ("generate-core-file", class_files, gcore_command,
 465            "\
 466 Save a core file with the current state of the debugged process.\n\
 467 Argument is optional filename.  Default filename is 'core.<process_id>'.");
 468
 469   add_com_alias ("gcore", "generate-core-file", class_files, 1);
 470   exec_set_find_memory_regions (objfile_find_memory_regions);
 471 }