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