gdb/gcore.c

   1 /* Generate a core file for the inferior process.
   2    Copyright 2001, 2002 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include "defs.h"
  22 #include "cli/cli-decode.h"
  23 #include "inferior.h"
  24 #include "gdbcore.h"
  25 #include "elf-bfd.h"
  26 #include "symfile.h"
  27 #include "objfiles.h"
  28
  29 static char                  *default_gcore_target (void);
  30 static enum bfd_architecture  default_gcore_arch (void);
  31 static unsigned long          default_gcore_mach (void);
  32 static int                    gcore_memory_sections (bfd *);
  33
  34 /* Function: gcore_command
  35    Generate a core file from the inferior process.  */
  36
  37 static void
  38 gcore_command (char *args, int from_tty)
  39 {
  40   struct cleanup *old_chain;
  41   char *corefilename, corefilename_buffer[40];
  42   asection *note_sec = NULL;
  43   bfd *obfd;
  44   void *note_data = NULL;
  45   int note_size = 0;
  46
  47   /* No use generating a corefile without a target process.  */
  48   if (!(target_has_execution))
  49     noprocess ();
  50
  51   if (args && *args)
  52     corefilename = args;
  53   else
  54     {
  55       /* Default corefile name is "core.PID".  */
  56       sprintf (corefilename_buffer, "core.%d", PIDGET (inferior_ptid));
  57       corefilename = corefilename_buffer;
  58     }
  59
  60   if (info_verbose)
  61     fprintf_filtered (gdb_stdout,
  62                       "Opening corefile '%s' for output.\n", corefilename);
  63
  64   /* Open the output file. */
  65   if (!(obfd = bfd_openw (corefilename, default_gcore_target ())))
  66     {
  67       error ("Failed to open '%s' for output.", corefilename);
  68     }
  69
  70   /* Need a cleanup that will close the file (FIXME: delete it?). */
  71   old_chain = make_cleanup_bfd_close (obfd);
  72
  73   bfd_set_format (obfd, bfd_core);
  74   bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ());
  75
  76   /* An external target method must build the notes section. */
  77   note_data = (char *) target_make_corefile_notes (obfd, &note_size);
  78
  79   /* Create the note section. */
  80   if (note_data != NULL && note_size != 0)
  81     {
  82       if ((note_sec = bfd_make_section_anyway (obfd, "note0")) == NULL)
  83         error ("Failed to create 'note' section for corefile: %s",
  84                bfd_errmsg (bfd_get_error ()));
  85
  86       bfd_set_section_vma (obfd, note_sec, 0);
  87       bfd_set_section_flags (obfd, note_sec,
  88                              SEC_HAS_CONTENTS | SEC_READONLY | SEC_ALLOC);
  89       bfd_set_section_alignment (obfd, note_sec, 0);
  90       bfd_set_section_size (obfd, note_sec, note_size);
  91     }
  92
  93   /* Now create the memory/load sections. */
  94   if (gcore_memory_sections (obfd) == 0)
  95     error ("gcore: failed to get corefile memory sections from target.");
  96
  97   /* Write out the contents of the note section. */
  98   if (note_data != NULL && note_size != 0)
  99     {
 100       if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size))
 101         {
 102           warning ("writing note section (%s)",
 103                    bfd_errmsg (bfd_get_error ()));
 104         }
 105     }
 106
 107   /* Succeeded. */
 108   fprintf_filtered (gdb_stdout,
 109                     "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 /*
 161  * Default method for stack segment (preemptable by target).
 162  */
 163
 164 static int (*override_derive_stack_segment) (bfd_vma *, bfd_vma *);
 165
 166 extern void
 167 preempt_derive_stack_segment (int (*override_func) (bfd_vma *, bfd_vma *))
 168 {
 169   override_derive_stack_segment = override_func;
 170 }
 171
 172 /* Function: default_derive_stack_segment
 173    Derive a reasonable stack segment by unwinding the target stack.
 174
 175    Returns 0 for failure, 1 for success.  */
 176
 177 static int
 178 default_derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
 179 {
 180   bfd_vma tmp_vma;
 181   struct frame_info *fi, *tmp_fi;
 182
 183   if (bottom == NULL || top == NULL)
 184     return 0;   /* Paranoia. */
 185
 186   if (!target_has_stack || !target_has_registers)
 187     return 0;   /* Can't succeed without stack and registers. */
 188
 189   if ((fi = get_current_frame ()) == NULL)
 190     return 0;   /* Can't succeed without current frame. */
 191
 192   /* Save frame pointer of TOS frame. */
 193   *top = fi->frame;
 194   /* If current stack pointer is more "inner", use that instead. */
 195   if (INNER_THAN (read_sp (), *top))
 196     *top = read_sp ();
 197
 198   /* Find prev-most frame. */
 199   while ((tmp_fi = get_prev_frame (fi)) != NULL)
 200     fi = tmp_fi;
 201
 202   /* Save frame pointer of prev-most frame. */
 203   *bottom = fi->frame;
 204
 205   /* Now canonicalize their order, so that 'bottom' is a lower address
 206    (as opposed to a lower stack frame). */
 207   if (*bottom > *top)
 208     {
 209       tmp_vma = *top;
 210       *top = *bottom;
 211       *bottom = tmp_vma;
 212     }
 213
 214   return 1;     /* success */
 215 }
 216
 217 static int
 218 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
 219 {
 220   if (override_derive_stack_segment)
 221     return override_derive_stack_segment (bottom, top);
 222   else
 223     return default_derive_stack_segment (bottom, top);
 224 }
 225
 226 /*
 227  * Default method for heap segment (preemptable by target).
 228  */
 229
 230 static int (*override_derive_heap_segment) (bfd *, bfd_vma *, bfd_vma *);
 231
 232 extern void
 233 preempt_derive_heap_segment (int (*override_func) (bfd *,
 234                                                    bfd_vma *, bfd_vma *))
 235 {
 236   override_derive_heap_segment = override_func;
 237 }
 238
 239 /* Function: default_derive_heap_segment
 240    Derive a reasonable heap segment by looking at sbrk and
 241    the static data sections.
 242
 243    Returns 0 for failure, 1 for success.  */
 244
 245 static int
 246 default_derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
 247 {
 248   bfd_vma top_of_data_memory = 0;
 249   bfd_vma top_of_heap = 0;
 250   bfd_size_type sec_size;
 251   struct value *zero, *sbrk;
 252   bfd_vma sec_vaddr;
 253   asection *sec;
 254
 255   if (bottom == NULL || top == NULL)
 256     return 0;           /* Paranoia. */
 257
 258   if (!target_has_execution)
 259     return 0;           /* This function depends on being able
 260                            to call a function in the inferior.  */
 261
 262   /* Assumption: link map is arranged as follows (low to high addresses):
 263      text sections
 264      data sections (including bss)
 265      heap
 266   */
 267
 268   for (sec = abfd->sections; sec; sec = sec->next)
 269     {
 270       if (bfd_get_section_flags (abfd, sec) & SEC_DATA ||
 271           strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
 272         {
 273           sec_vaddr = bfd_get_section_vma (abfd, sec);
 274           sec_size = bfd_get_section_size_before_reloc (sec);
 275           if (sec_vaddr + sec_size > top_of_data_memory)
 276             top_of_data_memory = sec_vaddr + sec_size;
 277         }
 278     }
 279   /* Now get the top-of-heap by calling sbrk in the inferior.  */
 280   if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL)
 281     {
 282       if ((sbrk = find_function_in_inferior ("sbrk")) == NULL)
 283         return 0;
 284     }
 285   else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL)
 286     {
 287       if ((sbrk = find_function_in_inferior ("_sbrk")) == NULL)
 288         return 0;
 289     }
 290   else
 291     return 0;
 292
 293   if ((zero = value_from_longest (builtin_type_int, (LONGEST) 0)) == NULL)
 294     return 0;
 295   if ((sbrk = call_function_by_hand (sbrk, 1, &zero)) == NULL)
 296     return 0;
 297   top_of_heap = value_as_long (sbrk);
 298
 299   /* Return results. */
 300   if (top_of_heap > top_of_data_memory)
 301     {
 302       *bottom = top_of_data_memory;
 303       *top = top_of_heap;
 304       return 1; /* success */
 305     }
 306   else
 307     return 0;   /* No additional heap space needs to be saved. */
 308 }
 309
 310 static int
 311 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
 312 {
 313   if (override_derive_heap_segment)
 314     return override_derive_heap_segment (abfd, bottom, top);
 315   else
 316     return default_derive_heap_segment (abfd, bottom, top);
 317 }
 318
 319 /* ARGSUSED */
 320 static void
 321 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
 322 {
 323   int p_flags = 0;
 324   int p_type;
 325
 326   /* FIXME: these constants may only be applicable for ELF.  */
 327   if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0)
 328     p_type = PT_LOAD;
 329   else
 330     p_type = PT_NOTE;
 331
 332   p_flags |= PF_R;      /* Segment is readable.  */
 333   if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
 334     p_flags |= PF_W;    /* Segment is writable.  */
 335   if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
 336     p_flags |= PF_X;    /* Segment is executable.  */
 337
 338   bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0,
 339                    0, 0, 1, &osec);
 340 }
 341
 342 static asection *
 343 make_mem_sec (bfd *obfd,
 344               bfd_vma addr,
 345               bfd_size_type size,
 346               unsigned int flags,
 347               unsigned int alignment)
 348 {
 349   asection *osec;
 350
 351   if ((osec = bfd_make_section_anyway (obfd, "load")) == NULL)
 352     {
 353       warning ("Couldn't make gcore segment: %s",
 354                bfd_errmsg (bfd_get_error ()));
 355       return NULL;
 356     }
 357
 358   if (info_verbose)
 359     {
 360       fprintf_filtered (gdb_stdout,
 361                         "Save segment, %lld bytes at 0x%s\n",
 362                         (long long) size, paddr_nz (addr));
 363     }
 364
 365   bfd_set_section_size (obfd, osec, size);
 366   bfd_set_section_vma (obfd, osec, addr);
 367   osec->lma = 0;        /* FIXME: there should be a macro for this! */
 368   bfd_set_section_alignment (obfd, osec, alignment);
 369   bfd_set_section_flags (obfd, osec,
 370                          flags | SEC_LOAD | SEC_ALLOC | SEC_HAS_CONTENTS);
 371   return osec;
 372 }
 373
 374 static int
 375 gcore_create_callback (CORE_ADDR vaddr,
 376                        unsigned long size,
 377                        int read, int write, int exec,
 378                        void *data)
 379 {
 380   flagword flags = 0;
 381
 382   if (write == 0)
 383     {
 384       flags |= SEC_READONLY;
 385       /* Set size == zero for readonly sections. */
 386       size = 0;
 387     }
 388   if (exec)
 389     {
 390       flags |= SEC_CODE;
 391     }
 392   else
 393     {
 394       flags |= SEC_DATA;
 395     }
 396
 397   return ((make_mem_sec ((bfd *) data, vaddr, size, flags, 0)) == NULL);
 398 }
 399
 400 static int
 401 objfile_find_memory_regions (int (*func) (CORE_ADDR,
 402                                           unsigned long,
 403                                           int, int, int,
 404                                            void *),
 405                              void *obfd)
 406 {
 407   /* Use objfile data to create memory sections. */
 408   struct objfile *objfile;
 409   struct obj_section *objsec;
 410   bfd_vma temp_bottom, temp_top;
 411
 412   /* Call callback function for each objfile section. */
 413   ALL_OBJSECTIONS (objfile, objsec)
 414     {
 415       bfd *ibfd = objfile->obfd;
 416       asection *isec = objsec->the_bfd_section;
 417       flagword flags = bfd_get_section_flags (ibfd, isec);
 418       int ret;
 419
 420       if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
 421         {
 422           int size = bfd_section_size (ibfd, isec);
 423           int ret;
 424
 425           if ((ret = (*func) (objsec->addr,
 426                               bfd_section_size (ibfd, isec),
 427                               1, /* All sections will be readable.  */
 428                               (flags & SEC_READONLY) == 0, /* writable */
 429                               (flags & SEC_CODE) != 0, /* executable */
 430                               obfd)) != 0)
 431             return ret;
 432         }
 433     }
 434
 435   /* Make a stack segment. */
 436   if (derive_stack_segment (&temp_bottom, &temp_top))
 437     (*func) (temp_bottom,
 438              temp_top - temp_bottom,
 439              1, /* Stack section will be readable */
 440              1, /* Stack section will be writable */
 441              0, /* Stack section will not be executable */
 442              obfd);
 443
 444   /* Make a heap segment. */
 445   if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
 446     (*func) (temp_bottom,
 447              temp_top - temp_bottom,
 448              1, /* Heap section will be readable */
 449              1, /* Heap section will be writable */
 450              0, /* Heap section will not be executable */
 451              obfd);
 452   return 0;
 453 }
 454
 455 static void
 456 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
 457 {
 458   bfd_size_type size = bfd_section_size (obfd, osec);
 459   struct cleanup *old_chain = NULL;
 460   void *memhunk;
 461
 462   if (size == 0)
 463     return;     /* Read-only sections are marked as zero-size.
 464                    We don't have to copy their contents. */
 465   if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0)
 466     return;     /* Only interested in "load" sections. */
 467
 468   if ((memhunk = xmalloc (size)) == NULL)
 469     error ("Not enough memory to create corefile.");
 470   old_chain = make_cleanup (xfree, memhunk);
 471
 472   if (target_read_memory (bfd_section_vma (obfd, osec),
 473                           memhunk, size) != 0)
 474     warning ("Memory read failed for corefile section, %ld bytes at 0x%s\n",
 475              (long) size, paddr (bfd_section_vma (obfd, osec)));
 476   if (!bfd_set_section_contents (obfd, osec, memhunk, 0, size))
 477     warning ("Failed to write corefile contents (%s).",
 478              bfd_errmsg (bfd_get_error ()));
 479
 480   do_cleanups (old_chain);      /* frees the xmalloc buffer */
 481 }
 482
 483 static int
 484 gcore_memory_sections (bfd *obfd)
 485 {
 486   if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
 487     return 0;   /* FIXME error return/msg? */
 488
 489   /* Record phdrs for section-to-segment mapping. */
 490   bfd_map_over_sections (obfd, make_output_phdrs, NULL);
 491
 492   /* Copy memory region contents. */
 493   bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
 494
 495   return 1;     /* success */
 496 }
 497
 498 void
 499 _initialize_gcore (void)
 500 {
 501   add_com ("generate-core-file", class_files, gcore_command,
 502            "Save a core file with the current state of the debugged process.\n\
 503 Argument is optional filename.  Default filename is 'core.<process_id>'.");
 504
 505   add_com_alias ("gcore", "generate-core-file", class_files, 1);
 506   exec_set_find_memory_regions (objfile_find_memory_regions);
 507 }