gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
   5    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software
   6    Foundation, Inc.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 59 Temple Place - Suite 330,
  23    Boston, MA 02111-1307, USA.  */
  24
  25 #include "defs.h"
  26 #include "symtab.h"
  27 #include "bfd.h"
  28 #include "symfile.h"
  29 #include "objfiles.h"
  30 #include "frame.h"
  31 #include "gdbcore.h"
  32 #include "value.h"              /* for read_register */
  33 #include "target.h"             /* for target_has_stack */
  34 #include "inferior.h"           /* for read_pc */
  35 #include "annotate.h"
  36 #include "regcache.h"
  37 #include "gdb_assert.h"
  38 #include "dummy-frame.h"
  39 #include "command.h"
  40 #include "gdbcmd.h"
  41 #include "block.h"
  42
  43 /* Prototypes for exported functions. */
  44
  45 void _initialize_blockframe (void);
  46
  47 /* Is ADDR inside the startup file?  Note that if your machine has a
  48    way to detect the bottom of the stack, there is no need to call
  49    this function from DEPRECATED_FRAME_CHAIN_VALID; the reason for
  50    doing so is that some machines have no way of detecting bottom of
  51    stack.
  52
  53    A PC of zero is always considered to be the bottom of the stack. */
  54
  55 int
  56 inside_entry_file (CORE_ADDR addr)
  57 {
  58   if (addr == 0)
  59     return 1;
  60   if (symfile_objfile == 0)
  61     return 0;
  62   if (CALL_DUMMY_LOCATION == AT_ENTRY_POINT)
  63     {
  64       /* Do not stop backtracing if the pc is in the call dummy
  65          at the entry point.  */
  66       /* FIXME: Won't always work with zeros for the last two arguments */
  67       if (DEPRECATED_PC_IN_CALL_DUMMY (addr, 0, 0))
  68         return 0;
  69     }
  70   return (addr >= symfile_objfile->ei.entry_file_lowpc &&
  71           addr < symfile_objfile->ei.entry_file_highpc);
  72 }
  73
  74 /* Test a specified PC value to see if it is in the range of addresses
  75    that correspond to the main() function.  See comments above for why
  76    we might want to do this.
  77
  78    Typically called from DEPRECATED_FRAME_CHAIN_VALID.
  79
  80    A PC of zero is always considered to be the bottom of the stack. */
  81
  82 int
  83 inside_main_func (CORE_ADDR pc)
  84 {
  85   if (pc == 0)
  86     return 1;
  87   if (symfile_objfile == 0)
  88     return 0;
  89
  90   /* If the addr range is not set up at symbol reading time, set it up
  91      now.  This is for DEPRECATED_FRAME_CHAIN_VALID_ALTERNATE. I do
  92      this for coff, because it is unable to set it up and symbol
  93      reading time. */
  94
  95   if (symfile_objfile->ei.main_func_lowpc == INVALID_ENTRY_LOWPC &&
  96       symfile_objfile->ei.main_func_highpc == INVALID_ENTRY_HIGHPC)
  97     {
  98       struct symbol *mainsym;
  99
 100       mainsym = lookup_symbol (main_name (), NULL, VAR_DOMAIN, NULL, NULL);
 101       if (mainsym && SYMBOL_CLASS (mainsym) == LOC_BLOCK)
 102         {
 103           symfile_objfile->ei.main_func_lowpc =
 104             BLOCK_START (SYMBOL_BLOCK_VALUE (mainsym));
 105           symfile_objfile->ei.main_func_highpc =
 106             BLOCK_END (SYMBOL_BLOCK_VALUE (mainsym));
 107         }
 108     }
 109   return (symfile_objfile->ei.main_func_lowpc <= pc &&
 110           symfile_objfile->ei.main_func_highpc > pc);
 111 }
 112
 113 /* Test a specified PC value to see if it is in the range of addresses
 114    that correspond to the process entry point function.  See comments
 115    in objfiles.h for why we might want to do this.
 116
 117    Typically called from DEPRECATED_FRAME_CHAIN_VALID.
 118
 119    A PC of zero is always considered to be the bottom of the stack. */
 120
 121 int
 122 inside_entry_func (CORE_ADDR pc)
 123 {
 124   if (pc == 0)
 125     return 1;
 126   if (symfile_objfile == 0)
 127     return 0;
 128   if (CALL_DUMMY_LOCATION == AT_ENTRY_POINT)
 129     {
 130       /* Do not stop backtracing if the pc is in the call dummy
 131          at the entry point.  */
 132       /* FIXME: Won't always work with zeros for the last two arguments */
 133       if (DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0))
 134         return 0;
 135     }
 136   return (symfile_objfile->ei.entry_func_lowpc <= pc &&
 137           symfile_objfile->ei.entry_func_highpc > pc);
 138 }
 139
 140 /* Return nonzero if the function for this frame lacks a prologue.  Many
 141    machines can define FRAMELESS_FUNCTION_INVOCATION to just call this
 142    function.  */
 143
 144 int
 145 frameless_look_for_prologue (struct frame_info *frame)
 146 {
 147   CORE_ADDR func_start;
 148
 149   func_start = get_frame_func (frame);
 150   if (func_start)
 151     {
 152       func_start += FUNCTION_START_OFFSET;
 153       /* This is faster, since only care whether there *is* a
 154          prologue, not how long it is.  */
 155       return PROLOGUE_FRAMELESS_P (func_start);
 156     }
 157   else if (get_frame_pc (frame) == 0)
 158     /* A frame with a zero PC is usually created by dereferencing a
 159        NULL function pointer, normally causing an immediate core dump
 160        of the inferior. Mark function as frameless, as the inferior
 161        has no chance of setting up a stack frame.  */
 162     return 1;
 163   else
 164     /* If we can't find the start of the function, we don't really
 165        know whether the function is frameless, but we should be able
 166        to get a reasonable (i.e. best we can do under the
 167        circumstances) backtrace by saying that it isn't.  */
 168     return 0;
 169 }
 170
 171 /* return the address of the PC for the given FRAME, ie the current PC value
 172    if FRAME is the innermost frame, or the address adjusted to point to the
 173    call instruction if not.  */
 174
 175 CORE_ADDR
 176 frame_address_in_block (struct frame_info *frame)
 177 {
 178   CORE_ADDR pc = get_frame_pc (frame);
 179
 180   /* If we are not in the innermost frame, and we are not interrupted
 181      by a signal, frame->pc points to the instruction following the
 182      call. As a consequence, we need to get the address of the previous
 183      instruction. Unfortunately, this is not straightforward to do, so
 184      we just use the address minus one, which is a good enough
 185      approximation.  */
 186   /* FIXME: cagney/2002-11-10: Should this instead test for
 187      NORMAL_FRAME?  A dummy frame (in fact all the abnormal frames)
 188      save the PC value in the block.  */
 189   if (get_next_frame (frame) != 0
 190       && get_frame_type (get_next_frame (frame)) != SIGTRAMP_FRAME)
 191     --pc;
 192
 193   return pc;
 194 }
 195
 196 /* Return the innermost lexical block in execution
 197    in a specified stack frame.  The frame address is assumed valid.
 198
 199    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
 200    address we used to choose the block.  We use this to find a source
 201    line, to decide which macro definitions are in scope.
 202
 203    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
 204    PC, and may not really be a valid PC at all.  For example, in the
 205    caller of a function declared to never return, the code at the
 206    return address will never be reached, so the call instruction may
 207    be the very last instruction in the block.  So the address we use
 208    to choose the block is actually one byte before the return address
 209    --- hopefully pointing us at the call instruction, or its delay
 210    slot instruction.  */
 211
 212 struct block *
 213 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
 214 {
 215   const CORE_ADDR pc = frame_address_in_block (frame);
 216
 217   if (addr_in_block)
 218     *addr_in_block = pc;
 219
 220   return block_for_pc (pc);
 221 }
 222
 223 CORE_ADDR
 224 get_pc_function_start (CORE_ADDR pc)
 225 {
 226   struct block *bl;
 227   struct minimal_symbol *msymbol;
 228
 229   bl = block_for_pc (pc);
 230   if (bl)
 231     {
 232       struct symbol *symbol = block_function (bl);
 233
 234       if (symbol)
 235         {
 236           bl = SYMBOL_BLOCK_VALUE (symbol);
 237           return BLOCK_START (bl);
 238         }
 239     }
 240
 241   msymbol = lookup_minimal_symbol_by_pc (pc);
 242   if (msymbol)
 243     {
 244       CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol);
 245
 246       if (find_pc_section (fstart))
 247         return fstart;
 248     }
 249
 250   return 0;
 251 }
 252
 253 /* Return the symbol for the function executing in frame FRAME.  */
 254
 255 struct symbol *
 256 get_frame_function (struct frame_info *frame)
 257 {
 258   register struct block *bl = get_frame_block (frame, 0);
 259   if (bl == 0)
 260     return 0;
 261   return block_function (bl);
 262 }
 263 \f
 264
 265 /* Return the function containing pc value PC in section SECTION.
 266    Returns 0 if function is not known.  */
 267
 268 struct symbol *
 269 find_pc_sect_function (CORE_ADDR pc, struct sec *section)
 270 {
 271   register struct block *b = block_for_pc_sect (pc, section);
 272   if (b == 0)
 273     return 0;
 274   return block_function (b);
 275 }
 276
 277 /* Return the function containing pc value PC.
 278    Returns 0 if function is not known.  Backward compatibility, no section */
 279
 280 struct symbol *
 281 find_pc_function (CORE_ADDR pc)
 282 {
 283   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 284 }
 285
 286 /* These variables are used to cache the most recent result
 287  * of find_pc_partial_function. */
 288
 289 static CORE_ADDR cache_pc_function_low = 0;
 290 static CORE_ADDR cache_pc_function_high = 0;
 291 static char *cache_pc_function_name = 0;
 292 static struct sec *cache_pc_function_section = NULL;
 293
 294 /* Clear cache, e.g. when symbol table is discarded. */
 295
 296 void
 297 clear_pc_function_cache (void)
 298 {
 299   cache_pc_function_low = 0;
 300   cache_pc_function_high = 0;
 301   cache_pc_function_name = (char *) 0;
 302   cache_pc_function_section = NULL;
 303 }
 304
 305 /* Finds the "function" (text symbol) that is smaller than PC but
 306    greatest of all of the potential text symbols in SECTION.  Sets
 307    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 308    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 309    function (exclusive), but passing ENDADDR as non-null means that
 310    the function might cause symbols to be read.  This function either
 311    succeeds or fails (not halfway succeeds).  If it succeeds, it sets
 312    *NAME, *ADDRESS, and *ENDADDR to real information and returns 1.
 313    If it fails, it sets *NAME, *ADDRESS, and *ENDADDR to zero and
 314    returns 0.  */
 315
 316 int
 317 find_pc_sect_partial_function (CORE_ADDR pc, asection *section, char **name,
 318                                CORE_ADDR *address, CORE_ADDR *endaddr)
 319 {
 320   struct partial_symtab *pst;
 321   struct symbol *f;
 322   struct minimal_symbol *msymbol;
 323   struct partial_symbol *psb;
 324   struct obj_section *osect;
 325   int i;
 326   CORE_ADDR mapped_pc;
 327
 328   mapped_pc = overlay_mapped_address (pc, section);
 329
 330   if (mapped_pc >= cache_pc_function_low
 331       && mapped_pc < cache_pc_function_high
 332       && section == cache_pc_function_section)
 333     goto return_cached_value;
 334
 335   /* If sigtramp is in the u area, it counts as a function (especially
 336      important for step_1).  */
 337   if (SIGTRAMP_START_P () && PC_IN_SIGTRAMP (mapped_pc, (char *) NULL))
 338     {
 339       cache_pc_function_low = SIGTRAMP_START (mapped_pc);
 340       cache_pc_function_high = SIGTRAMP_END (mapped_pc);
 341       cache_pc_function_name = "<sigtramp>";
 342       cache_pc_function_section = section;
 343       goto return_cached_value;
 344     }
 345
 346   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 347   pst = find_pc_sect_psymtab (mapped_pc, section);
 348   if (pst)
 349     {
 350       /* Need to read the symbols to get a good value for the end address.  */
 351       if (endaddr != NULL && !pst->readin)
 352         {
 353           /* Need to get the terminal in case symbol-reading produces
 354              output.  */
 355           target_terminal_ours_for_output ();
 356           PSYMTAB_TO_SYMTAB (pst);
 357         }
 358
 359       if (pst->readin)
 360         {
 361           /* Checking whether the msymbol has a larger value is for the
 362              "pathological" case mentioned in print_frame_info.  */
 363           f = find_pc_sect_function (mapped_pc, section);
 364           if (f != NULL
 365               && (msymbol == NULL
 366                   || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 367                       >= SYMBOL_VALUE_ADDRESS (msymbol))))
 368             {
 369               cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 370               cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 371               cache_pc_function_name = DEPRECATED_SYMBOL_NAME (f);
 372               cache_pc_function_section = section;
 373               goto return_cached_value;
 374             }
 375         }
 376       else
 377         {
 378           /* Now that static symbols go in the minimal symbol table, perhaps
 379              we could just ignore the partial symbols.  But at least for now
 380              we use the partial or minimal symbol, whichever is larger.  */
 381           psb = find_pc_sect_psymbol (pst, mapped_pc, section);
 382
 383           if (psb
 384               && (msymbol == NULL ||
 385                   (SYMBOL_VALUE_ADDRESS (psb)
 386                    >= SYMBOL_VALUE_ADDRESS (msymbol))))
 387             {
 388               /* This case isn't being cached currently. */
 389               if (address)
 390                 *address = SYMBOL_VALUE_ADDRESS (psb);
 391               if (name)
 392                 *name = DEPRECATED_SYMBOL_NAME (psb);
 393               /* endaddr non-NULL can't happen here.  */
 394               return 1;
 395             }
 396         }
 397     }
 398
 399   /* Not in the normal symbol tables, see if the pc is in a known section.
 400      If it's not, then give up.  This ensures that anything beyond the end
 401      of the text seg doesn't appear to be part of the last function in the
 402      text segment.  */
 403
 404   osect = find_pc_sect_section (mapped_pc, section);
 405
 406   if (!osect)
 407     msymbol = NULL;
 408
 409   /* Must be in the minimal symbol table.  */
 410   if (msymbol == NULL)
 411     {
 412       /* No available symbol.  */
 413       if (name != NULL)
 414         *name = 0;
 415       if (address != NULL)
 416         *address = 0;
 417       if (endaddr != NULL)
 418         *endaddr = 0;
 419       return 0;
 420     }
 421
 422   cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol);
 423   cache_pc_function_name = DEPRECATED_SYMBOL_NAME (msymbol);
 424   cache_pc_function_section = section;
 425
 426   /* Use the lesser of the next minimal symbol in the same section, or
 427      the end of the section, as the end of the function.  */
 428
 429   /* Step over other symbols at this same address, and symbols in
 430      other sections, to find the next symbol in this section with
 431      a different address.  */
 432
 433   for (i = 1; DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL; i++)
 434     {
 435       if (SYMBOL_VALUE_ADDRESS (msymbol + i) != SYMBOL_VALUE_ADDRESS (msymbol)
 436           && SYMBOL_BFD_SECTION (msymbol + i) == SYMBOL_BFD_SECTION (msymbol))
 437         break;
 438     }
 439
 440   if (DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL
 441       && SYMBOL_VALUE_ADDRESS (msymbol + i) < osect->endaddr)
 442     cache_pc_function_high = SYMBOL_VALUE_ADDRESS (msymbol + i);
 443   else
 444     /* We got the start address from the last msymbol in the objfile.
 445        So the end address is the end of the section.  */
 446     cache_pc_function_high = osect->endaddr;
 447
 448  return_cached_value:
 449
 450   if (address)
 451     {
 452       if (pc_in_unmapped_range (pc, section))
 453         *address = overlay_unmapped_address (cache_pc_function_low, section);
 454       else
 455         *address = cache_pc_function_low;
 456     }
 457
 458   if (name)
 459     *name = cache_pc_function_name;
 460
 461   if (endaddr)
 462     {
 463       if (pc_in_unmapped_range (pc, section))
 464         {
 465           /* Because the high address is actually beyond the end of
 466              the function (and therefore possibly beyond the end of
 467              the overlay), we must actually convert (high - 1) and
 468              then add one to that. */
 469
 470           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 471                                                    section);
 472         }
 473       else
 474         *endaddr = cache_pc_function_high;
 475     }
 476
 477   return 1;
 478 }
 479
 480 /* Backward compatibility, no section argument.  */
 481
 482 int
 483 find_pc_partial_function (CORE_ADDR pc, char **name, CORE_ADDR *address,
 484                           CORE_ADDR *endaddr)
 485 {
 486   asection *section;
 487
 488   section = find_pc_overlay (pc);
 489   return find_pc_sect_partial_function (pc, section, name, address, endaddr);
 490 }
 491
 492 /* Return the innermost stack frame executing inside of BLOCK,
 493    or NULL if there is no such frame.  If BLOCK is NULL, just return NULL.  */
 494
 495 struct frame_info *
 496 block_innermost_frame (struct block *block)
 497 {
 498   struct frame_info *frame;
 499   register CORE_ADDR start;
 500   register CORE_ADDR end;
 501   CORE_ADDR calling_pc;
 502
 503   if (block == NULL)
 504     return NULL;
 505
 506   start = BLOCK_START (block);
 507   end = BLOCK_END (block);
 508
 509   frame = NULL;
 510   while (1)
 511     {
 512       frame = get_prev_frame (frame);
 513       if (frame == NULL)
 514         return NULL;
 515       calling_pc = frame_address_in_block (frame);
 516       if (calling_pc >= start && calling_pc < end)
 517         return frame;
 518     }
 519 }
 520
 521 /* Are we in a call dummy?  The code below which allows DECR_PC_AFTER_BREAK
 522    below is for infrun.c, which may give the macro a pc without that
 523    subtracted out.  */
 524
 525 /* Is the PC in a call dummy?  SP and FRAME_ADDRESS are the bottom and
 526    top of the stack frame which we are checking, where "bottom" and
 527    "top" refer to some section of memory which contains the code for
 528    the call dummy.  Calls to this macro assume that the contents of
 529    SP_REGNUM and DEPRECATED_FP_REGNUM (or the saved values thereof),
 530    respectively, are the things to pass.
 531
 532    This won't work on the 29k, where SP_REGNUM and
 533    DEPRECATED_FP_REGNUM don't have that meaning, but the 29k doesn't
 534    use ON_STACK.  This could be fixed by generalizing this scheme,
 535    perhaps by passing in a frame and adding a few fields, at least on
 536    machines which need them for DEPRECATED_PC_IN_CALL_DUMMY.
 537
 538    Something simpler, like checking for the stack segment, doesn't work,
 539    since various programs (threads implementations, gcc nested function
 540    stubs, etc) may either allocate stack frames in another segment, or
 541    allocate other kinds of code on the stack.  */
 542
 543 int
 544 deprecated_pc_in_call_dummy_on_stack (CORE_ADDR pc, CORE_ADDR sp,
 545                                       CORE_ADDR frame_address)
 546 {
 547   return (INNER_THAN ((sp), (pc))
 548           && (frame_address != 0)
 549           && INNER_THAN ((pc), (frame_address)));
 550 }
 551
 552 int
 553 deprecated_pc_in_call_dummy_at_entry_point (CORE_ADDR pc, CORE_ADDR sp,
 554                                             CORE_ADDR frame_address)
 555 {
 556   return ((pc) >= CALL_DUMMY_ADDRESS ()
 557           && (pc) <= (CALL_DUMMY_ADDRESS () + DECR_PC_AFTER_BREAK));
 558 }
 559
 560 /* Returns true for a user frame or a call_function_by_hand dummy
 561    frame, and false for the CRT0 start-up frame.  Purpose is to
 562    terminate backtrace.  */
 563
 564 int
 565 legacy_frame_chain_valid (CORE_ADDR fp, struct frame_info *fi)
 566 {
 567   /* Don't prune CALL_DUMMY frames.  */
 568   if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES
 569       && DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (fi), 0, 0))
 570     return 1;
 571
 572   /* If the new frame pointer is zero, then it isn't valid.  */
 573   if (fp == 0)
 574     return 0;
 575
 576   /* If the new frame would be inside (younger than) the previous frame,
 577      then it isn't valid.  */
 578   if (INNER_THAN (fp, get_frame_base (fi)))
 579     return 0;
 580
 581   /* If the architecture has a custom DEPRECATED_FRAME_CHAIN_VALID,
 582      call it now.  */
 583   if (DEPRECATED_FRAME_CHAIN_VALID_P ())
 584     return DEPRECATED_FRAME_CHAIN_VALID (fp, fi);
 585
 586   /* If we're already inside the entry function for the main objfile, then it
 587      isn't valid.  */
 588   if (inside_entry_func (get_frame_pc (fi)))
 589     return 0;
 590
 591   /* If we're inside the entry file, it isn't valid.  */
 592   /* NOTE/drow 2002-12-25: should there be a way to disable this check?  It
 593      assumes a single small entry file, and the way some debug readers (e.g.
 594      dbxread) figure out which object is the entry file is somewhat hokey.  */
 595   if (inside_entry_file (frame_pc_unwind (fi)))
 596       return 0;
 597
 598   return 1;
 599 }