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 <sys/procfs.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 /*
 162  * Default method for stack segment (preemptable by target).
 163  */
 164
 165 static int (*override_derive_stack_segment) (bfd_vma *, bfd_vma *);
 166
 167 extern void
 168 preempt_derive_stack_segment (int (*override_func) (bfd_vma *, bfd_vma *))
 169 {
 170   override_derive_stack_segment = override_func;
 171 }
 172
 173 /* Function: default_derive_stack_segment
 174    Derive a reasonable stack segment by unwinding the target stack.
 175
 176    Returns 0 for failure, 1 for success.  */
 177
 178 static int
 179 default_derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
 180 {
 181   bfd_vma tmp_vma;
 182   struct frame_info *fi, *tmp_fi;
 183
 184   if (bottom == NULL || top == NULL)
 185     return 0;   /* Paranoia. */
 186
 187   if (!target_has_stack || !target_has_registers)
 188     return 0;   /* Can't succeed without stack and registers. */
 189
 190   if ((fi = get_current_frame ()) == NULL)
 191     return 0;   /* Can't succeed without current frame. */
 192
 193   /* Save frame pointer of TOS frame. */
 194   *top = fi->frame;
 195   /* If current stack pointer is more "inner", use that instead. */
 196   if (INNER_THAN (read_sp (), *top))
 197     *top = read_sp ();
 198
 199   /* Find prev-most frame. */
 200   while ((tmp_fi = get_prev_frame (fi)) != NULL)
 201     fi = tmp_fi;
 202
 203   /* Save frame pointer of prev-most frame. */
 204   *bottom = fi->frame;
 205
 206   /* Now canonicalize their order, so that 'bottom' is a lower address
 207    (as opposed to a lower stack frame). */
 208   if (*bottom > *top)
 209     {
 210       tmp_vma = *top;
 211       *top = *bottom;
 212       *bottom = tmp_vma;
 213     }
 214
 215   return 1;     /* success */
 216 }
 217
 218 static int
 219 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
 220 {
 221   if (override_derive_stack_segment)
 222     return override_derive_stack_segment (bottom, top);
 223   else
 224     return default_derive_stack_segment (bottom, top);
 225 }
 226
 227 /*
 228  * Default method for heap segment (preemptable by target).
 229  */
 230
 231 static int (*override_derive_heap_segment) (bfd *, bfd_vma *, bfd_vma *);
 232
 233 extern void
 234 preempt_derive_heap_segment (int (*override_func) (bfd *,
 235                                                    bfd_vma *, bfd_vma *))
 236 {
 237   override_derive_heap_segment = override_func;
 238 }
 239
 240 /* Function: default_derive_heap_segment
 241    Derive a reasonable heap segment by looking at sbrk and
 242    the static data sections.
 243
 244    Returns 0 for failure, 1 for success.  */
 245
 246 static int
 247 default_derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
 248 {
 249   bfd_vma top_of_data_memory = 0;
 250   bfd_vma top_of_heap = 0;
 251   bfd_size_type sec_size;
 252   struct value *zero, *sbrk;
 253   bfd_vma sec_vaddr;
 254   asection *sec;
 255
 256   if (bottom == NULL || top == NULL)
 257     return 0;           /* Paranoia. */
 258
 259   if (!target_has_execution)
 260     return 0;           /* This function depends on being able
 261                            to call a function in the inferior.  */
 262
 263   /* Assumption: link map is arranged as follows (low to high addresses):
 264      text sections
 265      data sections (including bss)
 266      heap
 267   */
 268
 269   for (sec = abfd->sections; sec; sec = sec->next)
 270     {
 271       if (bfd_get_section_flags (abfd, sec) & SEC_DATA ||
 272           strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
 273         {
 274           sec_vaddr = bfd_get_section_vma (abfd, sec);
 275           sec_size = bfd_get_section_size_before_reloc (sec);
 276           if (sec_vaddr + sec_size > top_of_data_memory)
 277             top_of_data_memory = sec_vaddr + sec_size;
 278         }
 279     }
 280   /* Now get the top-of-heap by calling sbrk in the inferior.  */
 281   if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL)
 282     {
 283       if ((sbrk = find_function_in_inferior ("sbrk")) == NULL)
 284         return 0;
 285     }
 286   else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL)
 287     {
 288       if ((sbrk = find_function_in_inferior ("_sbrk")) == NULL)
 289         return 0;
 290     }
 291   else
 292     return 0;
 293
 294   if ((zero = value_from_longest (builtin_type_int, (LONGEST) 0)) == NULL)
 295     return 0;
 296   if ((sbrk = call_function_by_hand (sbrk, 1, &zero)) == NULL)
 297     return 0;
 298   top_of_heap = value_as_long (sbrk);
 299
 300   /* Return results. */
 301   if (top_of_heap > top_of_data_memory)
 302     {
 303       *bottom = top_of_data_memory;
 304       *top = top_of_heap;
 305       return 1; /* success */
 306     }
 307   else
 308     return 0;   /* No additional heap space needs to be saved. */
 309 }
 310
 311 static int
 312 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
 313 {
 314   if (override_derive_heap_segment)
 315     return override_derive_heap_segment (abfd, bottom, top);
 316   else
 317     return default_derive_heap_segment (abfd, bottom, top);
 318 }
 319
 320 /* ARGSUSED */
 321 static void
 322 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
 323 {
 324   int p_flags = 0;
 325   int p_type;
 326
 327   /* FIXME: these constants may only be applicable for ELF.  */
 328   if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0)
 329     p_type = PT_LOAD;
 330   else
 331     p_type = PT_NOTE;
 332
 333   p_flags |= PF_R;      /* Segment is readable.  */
 334   if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
 335     p_flags |= PF_W;    /* Segment is writable.  */
 336   if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
 337     p_flags |= PF_X;    /* Segment is executable.  */
 338
 339   bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0,
 340                    0, 0, 1, &osec);
 341 }
 342
 343 static asection *
 344 make_mem_sec (bfd *obfd,
 345               bfd_vma addr,
 346               bfd_size_type size,
 347               unsigned int flags,
 348               unsigned int alignment)
 349 {
 350   asection *osec;
 351
 352   if ((osec = bfd_make_section_anyway (obfd, "load")) == NULL)
 353     {
 354       warning ("Couldn't make gcore segment: %s",
 355                bfd_errmsg (bfd_get_error ()));
 356       return NULL;
 357     }
 358
 359   if (info_verbose)
 360     {
 361       fprintf_filtered (gdb_stdout,
 362                         "Save segment, %lld bytes at 0x%s\n",
 363                         (long long) size, paddr_nz (addr));
 364     }
 365
 366   bfd_set_section_size (obfd, osec, size);
 367   bfd_set_section_vma (obfd, osec, addr);
 368   osec->lma = 0;        /* FIXME: there should be a macro for this! */
 369   bfd_set_section_alignment (obfd, osec, alignment);
 370   bfd_set_section_flags (obfd, osec,
 371                          flags | SEC_LOAD | SEC_ALLOC | SEC_HAS_CONTENTS);
 372   return osec;
 373 }
 374
 375 static int
 376 gcore_create_callback (CORE_ADDR vaddr,
 377                        unsigned long size,
 378                        int read, int write, int exec,
 379                        void *data)
 380 {
 381   flagword flags = 0;
 382
 383   if (write == 0)
 384     {
 385       flags |= SEC_READONLY;
 386       /* Set size == zero for readonly sections. */
 387       size = 0;
 388     }
 389   if (exec)
 390     {
 391       flags |= SEC_CODE;
 392     }
 393   else
 394     {
 395       flags |= SEC_DATA;
 396     }
 397
 398   return ((make_mem_sec ((bfd *) data, vaddr, size, flags, 0)) == NULL);
 399 }
 400
 401 static int
 402 objfile_find_memory_regions (int (*func) (CORE_ADDR,
 403                                           unsigned long,
 404                                           int, int, int,
 405                                            void *),
 406                              void *obfd)
 407 {
 408   /* Use objfile data to create memory sections. */
 409   struct objfile *objfile;
 410   struct obj_section *objsec;
 411   bfd_vma temp_bottom, temp_top;
 412
 413   /* Call callback function for each objfile section. */
 414   ALL_OBJSECTIONS (objfile, objsec)
 415     {
 416       bfd *ibfd = objfile->obfd;
 417       asection *isec = objsec->the_bfd_section;
 418       flagword flags = bfd_get_section_flags (ibfd, isec);
 419       int ret;
 420
 421       if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
 422         {
 423           int size = bfd_section_size (ibfd, isec);
 424           int ret;
 425
 426           if ((ret = (*func) (objsec->addr,
 427                               bfd_section_size (ibfd, isec),
 428                               1, /* All sections will be readable.  */
 429                               (flags & SEC_READONLY) == 0, /* writable */
 430                               (flags & SEC_CODE) != 0, /* executable */
 431                               obfd)) != 0)
 432             return ret;
 433         }
 434     }
 435
 436   /* Make a stack segment. */
 437   if (derive_stack_segment (&temp_bottom, &temp_top))
 438     (*func) (temp_bottom,
 439              temp_top - temp_bottom,
 440              1, /* Stack section will be readable */
 441              1, /* Stack section will be writable */
 442              0, /* Stack section will not be executable */
 443              obfd);
 444
 445   /* Make a heap segment. */
 446   if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
 447     (*func) (temp_bottom,
 448              temp_top - temp_bottom,
 449              1, /* Heap section will be readable */
 450              1, /* Heap section will be writable */
 451              0, /* Heap section will not be executable */
 452              obfd);
 453   return 0;
 454 }
 455
 456 static void
 457 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
 458 {
 459   bfd_size_type size = bfd_section_size (obfd, osec);
 460   struct cleanup *old_chain = NULL;
 461   void *memhunk;
 462
 463   if (size == 0)
 464     return;     /* Read-only sections are marked as zero-size.
 465                    We don't have to copy their contents. */
 466   if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0)
 467     return;     /* Only interested in "load" sections. */
 468
 469   if ((memhunk = xmalloc (size)) == NULL)
 470     error ("Not enough memory to create corefile.");
 471   old_chain = make_cleanup (xfree, memhunk);
 472
 473   if (target_read_memory (bfd_section_vma (obfd, osec),
 474                           memhunk, size) != 0)
 475     warning ("Memory read failed for corefile section, %ld bytes at 0x%s\n",
 476              (long) size, paddr (bfd_section_vma (obfd, osec)));
 477   if (!bfd_set_section_contents (obfd, osec, memhunk, 0, size))
 478     warning ("Failed to write corefile contents (%s).",
 479              bfd_errmsg (bfd_get_error ()));
 480
 481   do_cleanups (old_chain);      /* frees the xmalloc buffer */
 482 }
 483
 484 static int
 485 gcore_memory_sections (bfd *obfd)
 486 {
 487   if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
 488     return 0;   /* FIXME error return/msg? */
 489
 490   /* Record phdrs for section-to-segment mapping. */
 491   bfd_map_over_sections (obfd, make_output_phdrs, NULL);
 492
 493   /* Copy memory region contents. */
 494   bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
 495
 496   return 1;     /* success */
 497 }
 498
 499 void
 500 _initialize_gcore (void)
 501 {
 502   add_com ("generate-core-file", class_files, gcore_command,
 503            "Save a core file with the current state of the debugged process.\n\
 504 Argument is optional filename.  Default filename is 'core.<process_id>'.");
 505
 506   add_com_alias ("gcore", "generate-core-file", class_files, 1);
 507   exec_set_find_memory_regions (objfile_find_memory_regions);
 508 }