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