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, 2004 6 Free Software 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 "objfiles.h" 29#include "frame.h" 30#include "gdbcore.h" 31#include "value.h" /* for read_register */ 32#include "target.h" /* for target_has_stack */ 33#include "inferior.h" /* for read_pc */ 34#include "annotate.h" 35#include "regcache.h" 36#include "gdb_assert.h" 37#include "dummy-frame.h" 38#include "command.h" 39#include "gdbcmd.h" 40#include "block.h" 41 42/* Prototypes for exported functions. */ 43 44void _initialize_blockframe (void); 45 46/* Is ADDR inside the startup file? Note that if your machine has a 47 way to detect the bottom of the stack, there is no need to call 48 this function from DEPRECATED_FRAME_CHAIN_VALID; the reason for 49 doing so is that some machines have no way of detecting bottom of 50 stack. 51 52 A PC of zero is always considered to be the bottom of the stack. */ 53 54int 55deprecated_inside_entry_file (CORE_ADDR addr) 56{ 57 if (addr == 0) 58 return 1; 59 if (symfile_objfile == 0) 60 return 0; 61 if (CALL_DUMMY_LOCATION == AT_ENTRY_POINT 62 || CALL_DUMMY_LOCATION == AT_SYMBOL) 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.deprecated_entry_file_lowpc && 71 addr < symfile_objfile->ei.deprecated_entry_file_highpc); 72} 73 74/* Test whether PC is in the range of addresses that corresponds to 75 the "main" function. */ 76 77int 78inside_main_func (CORE_ADDR pc) 79{ 80 struct minimal_symbol *msymbol; 81 82 if (symfile_objfile == 0) 83 return 0; 84 85 msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile); 86 87 /* If the address range hasn't been set up at symbol reading time, 88 set it up now. */ 89 90 if (msymbol != NULL 91 && symfile_objfile->ei.main_func_lowpc == INVALID_ENTRY_LOWPC 92 && symfile_objfile->ei.main_func_highpc == INVALID_ENTRY_HIGHPC) 93 { 94 /* brobecker/2003-10-10: We used to rely on lookup_symbol() to 95 search the symbol associated to the "main" function. 96 Unfortunately, lookup_symbol() uses the current-language 97 la_lookup_symbol_nonlocal function to do the global symbol 98 search. Depending on the language, this can introduce 99 certain side-effects, because certain languages, for instance 100 Ada, may find more than one match. Therefore we prefer to 101 search the "main" function symbol using its address rather 102 than its name. */ 103 struct symbol *mainsym = 104 find_pc_function (SYMBOL_VALUE_ADDRESS (msymbol)); 105 106 if (mainsym && SYMBOL_CLASS (mainsym) == LOC_BLOCK) 107 { 108 symfile_objfile->ei.main_func_lowpc = 109 BLOCK_START (SYMBOL_BLOCK_VALUE (mainsym)); 110 symfile_objfile->ei.main_func_highpc = 111 BLOCK_END (SYMBOL_BLOCK_VALUE (mainsym)); 112 } 113 } 114 115 /* Not in the normal symbol tables, see if "main" is in the partial 116 symbol table. If it's not, then give up. */ 117 if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_text) 118 { 119 CORE_ADDR maddr = SYMBOL_VALUE_ADDRESS (msymbol); 120 asection *msect = SYMBOL_BFD_SECTION (msymbol); 121 struct obj_section *osect = find_pc_sect_section (maddr, msect); 122 123 if (osect != NULL) 124 { 125 int i; 126 127 /* Step over other symbols at this same address, and symbols 128 in other sections, to find the next symbol in this 129 section with a different address. */ 130 for (i = 1; SYMBOL_LINKAGE_NAME (msymbol + i) != NULL; i++) 131 { 132 if (SYMBOL_VALUE_ADDRESS (msymbol + i) != maddr 133 && SYMBOL_BFD_SECTION (msymbol + i) == msect) 134 break; 135 } 136 137 symfile_objfile->ei.main_func_lowpc = maddr; 138 139 /* Use the lesser of the next minimal symbol in the same 140 section, or the end of the section, as the end of the 141 function. */ 142 if (SYMBOL_LINKAGE_NAME (msymbol + i) != NULL 143 && SYMBOL_VALUE_ADDRESS (msymbol + i) < osect->endaddr) 144 symfile_objfile->ei.main_func_highpc = 145 SYMBOL_VALUE_ADDRESS (msymbol + i); 146 else 147 /* We got the start address from the last msymbol in the 148 objfile. So the end address is the end of the 149 section. */ 150 symfile_objfile->ei.main_func_highpc = osect->endaddr; 151 } 152 } 153 154 return (symfile_objfile->ei.main_func_lowpc <= pc 155 && symfile_objfile->ei.main_func_highpc > pc); 156} 157 158/* Test whether THIS_FRAME is inside the process entry point function. */ 159 160int 161inside_entry_func (struct frame_info *this_frame) 162{ 163 return (get_frame_func (this_frame) == entry_point_address ()); 164} 165 166/* Similar to inside_entry_func, but accomodating legacy frame code. */ 167 168static int 169legacy_inside_entry_func (CORE_ADDR pc) 170{ 171 if (symfile_objfile == 0) 172 return 0; 173 174 if (CALL_DUMMY_LOCATION == AT_ENTRY_POINT) 175 { 176 /* Do not stop backtracing if the program counter is in the call 177 dummy at the entry point. */ 178 /* FIXME: This won't always work with zeros for the last two 179 arguments. */ 180 if (DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0)) 181 return 0; 182 } 183 184 return (symfile_objfile->ei.entry_func_lowpc <= pc 185 && symfile_objfile->ei.entry_func_highpc > pc); 186} 187 188/* Return nonzero if the function for this frame lacks a prologue. 189 Many machines can define DEPRECATED_FRAMELESS_FUNCTION_INVOCATION 190 to just call this function. */ 191 192int 193legacy_frameless_look_for_prologue (struct frame_info *frame) 194{ 195 CORE_ADDR func_start; 196 197 func_start = get_frame_func (frame); 198 if (func_start) 199 { 200 func_start += FUNCTION_START_OFFSET; 201 /* NOTE: cagney/2004-02-09: Eliminated per-architecture 202 PROLOGUE_FRAMELESS_P call as architectures with custom 203 implementations had all been deleted. Eventually even this 204 function can go - GDB no longer tries to differentiate 205 between framed, frameless and stackless functions. They are 206 all now considered equally evil :-^. */ 207 /* If skipping the prologue ends up skips nothing, there must be 208 no prologue and hence no code creating a frame. There for 209 the function is "frameless" :-/. */ 210 return func_start == SKIP_PROLOGUE (func_start); 211 } 212 else if (get_frame_pc (frame) == 0) 213 /* A frame with a zero PC is usually created by dereferencing a 214 NULL function pointer, normally causing an immediate core dump 215 of the inferior. Mark function as frameless, as the inferior 216 has no chance of setting up a stack frame. */ 217 return 1; 218 else 219 /* If we can't find the start of the function, we don't really 220 know whether the function is frameless, but we should be able 221 to get a reasonable (i.e. best we can do under the 222 circumstances) backtrace by saying that it isn't. */ 223 return 0; 224} 225 226/* Return the innermost lexical block in execution 227 in a specified stack frame. The frame address is assumed valid. 228 229 If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code 230 address we used to choose the block. We use this to find a source 231 line, to decide which macro definitions are in scope. 232 233 The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's 234 PC, and may not really be a valid PC at all. For example, in the 235 caller of a function declared to never return, the code at the 236 return address will never be reached, so the call instruction may 237 be the very last instruction in the block. So the address we use 238 to choose the block is actually one byte before the return address 239 --- hopefully pointing us at the call instruction, or its delay 240 slot instruction. */ 241 242struct block * 243get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block) 244{ 245 const CORE_ADDR pc = get_frame_address_in_block (frame); 246 247 if (addr_in_block) 248 *addr_in_block = pc; 249 250 return block_for_pc (pc); 251} 252 253CORE_ADDR 254get_pc_function_start (CORE_ADDR pc) 255{ 256 struct block *bl; 257 struct minimal_symbol *msymbol; 258 259 bl = block_for_pc (pc); 260 if (bl) 261 { 262 struct symbol *symbol = block_function (bl); 263 264 if (symbol) 265 { 266 bl = SYMBOL_BLOCK_VALUE (symbol); 267 return BLOCK_START (bl); 268 } 269 } 270 271 msymbol = lookup_minimal_symbol_by_pc (pc); 272 if (msymbol) 273 { 274 CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol); 275 276 if (find_pc_section (fstart)) 277 return fstart; 278 } 279 280 return 0; 281} 282 283/* Return the symbol for the function executing in frame FRAME. */ 284 285struct symbol * 286get_frame_function (struct frame_info *frame) 287{ 288 struct block *bl = get_frame_block (frame, 0); 289 if (bl == 0) 290 return 0; 291 return block_function (bl); 292} 293 294 295/* Return the function containing pc value PC in section SECTION. 296 Returns 0 if function is not known. */ 297 298struct symbol * 299find_pc_sect_function (CORE_ADDR pc, struct bfd_section *section) 300{ 301 struct block *b = block_for_pc_sect (pc, section); 302 if (b == 0) 303 return 0; 304 return block_function (b); 305} 306 307/* Return the function containing pc value PC. 308 Returns 0 if function is not known. Backward compatibility, no section */ 309 310struct symbol * 311find_pc_function (CORE_ADDR pc) 312{ 313 return find_pc_sect_function (pc, find_pc_mapped_section (pc)); 314} 315 316/* These variables are used to cache the most recent result 317 * of find_pc_partial_function. */ 318 319static CORE_ADDR cache_pc_function_low = 0; 320static CORE_ADDR cache_pc_function_high = 0; 321static char *cache_pc_function_name = 0; 322static struct bfd_section *cache_pc_function_section = NULL; 323 324/* Clear cache, e.g. when symbol table is discarded. */ 325 326void 327clear_pc_function_cache (void) 328{ 329 cache_pc_function_low = 0; 330 cache_pc_function_high = 0; 331 cache_pc_function_name = (char *) 0; 332 cache_pc_function_section = NULL; 333} 334 335/* Finds the "function" (text symbol) that is smaller than PC but 336 greatest of all of the potential text symbols in SECTION. Sets 337 *NAME and/or *ADDRESS conditionally if that pointer is non-null. 338 If ENDADDR is non-null, then set *ENDADDR to be the end of the 339 function (exclusive), but passing ENDADDR as non-null means that 340 the function might cause symbols to be read. This function either 341 succeeds or fails (not halfway succeeds). If it succeeds, it sets 342 *NAME, *ADDRESS, and *ENDADDR to real information and returns 1. 343 If it fails, it sets *NAME, *ADDRESS, and *ENDADDR to zero and 344 returns 0. */ 345 346int 347find_pc_sect_partial_function (CORE_ADDR pc, asection *section, char **name, 348 CORE_ADDR *address, CORE_ADDR *endaddr) 349{ 350 struct partial_symtab *pst; 351 struct symbol *f; 352 struct minimal_symbol *msymbol; 353 struct partial_symbol *psb; 354 struct obj_section *osect; 355 int i; 356 CORE_ADDR mapped_pc; 357 358 mapped_pc = overlay_mapped_address (pc, section); 359 360 if (mapped_pc >= cache_pc_function_low 361 && mapped_pc < cache_pc_function_high 362 && section == cache_pc_function_section) 363 goto return_cached_value; 364 365 /* If sigtramp is in the u area, it counts as a function (especially 366 important for step_1). */ 367 if (SIGTRAMP_START_P () && PC_IN_SIGTRAMP (mapped_pc, (char *) NULL)) 368 { 369 cache_pc_function_low = SIGTRAMP_START (mapped_pc); 370 cache_pc_function_high = SIGTRAMP_END (mapped_pc); 371 cache_pc_function_name = "<sigtramp>"; 372 cache_pc_function_section = section; 373 goto return_cached_value; 374 } 375 376 msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section); 377 pst = find_pc_sect_psymtab (mapped_pc, section); 378 if (pst) 379 { 380 /* Need to read the symbols to get a good value for the end address. */ 381 if (endaddr != NULL && !pst->readin) 382 { 383 /* Need to get the terminal in case symbol-reading produces 384 output. */ 385 target_terminal_ours_for_output (); 386 PSYMTAB_TO_SYMTAB (pst); 387 } 388 389 if (pst->readin) 390 { 391 /* Checking whether the msymbol has a larger value is for the 392 "pathological" case mentioned in print_frame_info. */ 393 f = find_pc_sect_function (mapped_pc, section); 394 if (f != NULL 395 && (msymbol == NULL 396 || (BLOCK_START (SYMBOL_BLOCK_VALUE (f)) 397 >= SYMBOL_VALUE_ADDRESS (msymbol)))) 398 { 399 cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f)); 400 cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f)); 401 cache_pc_function_name = DEPRECATED_SYMBOL_NAME (f); 402 cache_pc_function_section = section; 403 goto return_cached_value; 404 } 405 } 406 else 407 { 408 /* Now that static symbols go in the minimal symbol table, perhaps 409 we could just ignore the partial symbols. But at least for now 410 we use the partial or minimal symbol, whichever is larger. */ 411 psb = find_pc_sect_psymbol (pst, mapped_pc, section); 412 413 if (psb 414 && (msymbol == NULL || 415 (SYMBOL_VALUE_ADDRESS (psb) 416 >= SYMBOL_VALUE_ADDRESS (msymbol)))) 417 { 418 /* This case isn't being cached currently. */ 419 if (address) 420 *address = SYMBOL_VALUE_ADDRESS (psb); 421 if (name) 422 *name = DEPRECATED_SYMBOL_NAME (psb); 423 /* endaddr non-NULL can't happen here. */ 424 return 1; 425 } 426 } 427 } 428 429 /* Not in the normal symbol tables, see if the pc is in a known section. 430 If it's not, then give up. This ensures that anything beyond the end 431 of the text seg doesn't appear to be part of the last function in the 432 text segment. */ 433 434 osect = find_pc_sect_section (mapped_pc, section); 435 436 if (!osect) 437 msymbol = NULL; 438 439 /* Must be in the minimal symbol table. */ 440 if (msymbol == NULL) 441 { 442 /* No available symbol. */ 443 if (name != NULL) 444 *name = 0; 445 if (address != NULL) 446 *address = 0; 447 if (endaddr != NULL) 448 *endaddr = 0; 449 return 0; 450 } 451 452 cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol); 453 cache_pc_function_name = DEPRECATED_SYMBOL_NAME (msymbol); 454 cache_pc_function_section = section; 455 456 /* Use the lesser of the next minimal symbol in the same section, or 457 the end of the section, as the end of the function. */ 458 459 /* Step over other symbols at this same address, and symbols in 460 other sections, to find the next symbol in this section with 461 a different address. */ 462 463 for (i = 1; DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL; i++) 464 { 465 if (SYMBOL_VALUE_ADDRESS (msymbol + i) != SYMBOL_VALUE_ADDRESS (msymbol) 466 && SYMBOL_BFD_SECTION (msymbol + i) == SYMBOL_BFD_SECTION (msymbol)) 467 break; 468 } 469 470 if (DEPRECATED_SYMBOL_NAME (msymbol + i) != NULL 471 && SYMBOL_VALUE_ADDRESS (msymbol + i) < osect->endaddr) 472 cache_pc_function_high = SYMBOL_VALUE_ADDRESS (msymbol + i); 473 else 474 /* We got the start address from the last msymbol in the objfile. 475 So the end address is the end of the section. */ 476 cache_pc_function_high = osect->endaddr; 477 478 return_cached_value: 479 480 if (address) 481 { 482 if (pc_in_unmapped_range (pc, section)) 483 *address = overlay_unmapped_address (cache_pc_function_low, section); 484 else 485 *address = cache_pc_function_low; 486 } 487 488 if (name) 489 *name = cache_pc_function_name; 490 491 if (endaddr) 492 { 493 if (pc_in_unmapped_range (pc, section)) 494 { 495 /* Because the high address is actually beyond the end of 496 the function (and therefore possibly beyond the end of 497 the overlay), we must actually convert (high - 1) and 498 then add one to that. */ 499 500 *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1, 501 section); 502 } 503 else 504 *endaddr = cache_pc_function_high; 505 } 506 507 return 1; 508} 509 510/* Backward compatibility, no section argument. */ 511 512int 513find_pc_partial_function (CORE_ADDR pc, char **name, CORE_ADDR *address, 514 CORE_ADDR *endaddr) 515{ 516 struct bfd_section *bfd_section; 517 518 /* To ensure that the symbol returned belongs to the correct setion 519 (and that the last [random] symbol from the previous section 520 isn't returned) try to find the section containing PC. First try 521 the overlay code (which by default returns NULL); and second try 522 the normal section code (which almost always succeeds). */ 523 bfd_section = find_pc_overlay (pc); 524 if (bfd_section == NULL) 525 { 526 struct obj_section *obj_section = find_pc_section (pc); 527 if (obj_section == NULL) 528 bfd_section = NULL; 529 else 530 bfd_section = obj_section->the_bfd_section; 531 } 532 return find_pc_sect_partial_function (pc, bfd_section, name, address, 533 endaddr); 534} 535 536/* Return the innermost stack frame executing inside of BLOCK, 537 or NULL if there is no such frame. If BLOCK is NULL, just return NULL. */ 538 539struct frame_info * 540block_innermost_frame (struct block *block) 541{ 542 struct frame_info *frame; 543 CORE_ADDR start; 544 CORE_ADDR end; 545 CORE_ADDR calling_pc; 546 547 if (block == NULL) 548 return NULL; 549 550 start = BLOCK_START (block); 551 end = BLOCK_END (block); 552 553 frame = NULL; 554 while (1) 555 { 556 frame = get_prev_frame (frame); 557 if (frame == NULL) 558 return NULL; 559 calling_pc = get_frame_address_in_block (frame); 560 if (calling_pc >= start && calling_pc < end) 561 return frame; 562 } 563} 564 565/* Are we in a call dummy? The code below which allows DECR_PC_AFTER_BREAK 566 below is for infrun.c, which may give the macro a pc without that 567 subtracted out. */ 568 569/* Is the PC in a call dummy? SP and FRAME_ADDRESS are the bottom and 570 top of the stack frame which we are checking, where "bottom" and 571 "top" refer to some section of memory which contains the code for 572 the call dummy. Calls to this macro assume that the contents of 573 SP_REGNUM and DEPRECATED_FP_REGNUM (or the saved values thereof), 574 respectively, are the things to pass. 575 576 This won't work on the 29k, where SP_REGNUM and 577 DEPRECATED_FP_REGNUM don't have that meaning, but the 29k doesn't 578 use ON_STACK. This could be fixed by generalizing this scheme, 579 perhaps by passing in a frame and adding a few fields, at least on 580 machines which need them for DEPRECATED_PC_IN_CALL_DUMMY. 581 582 Something simpler, like checking for the stack segment, doesn't work, 583 since various programs (threads implementations, gcc nested function 584 stubs, etc) may either allocate stack frames in another segment, or 585 allocate other kinds of code on the stack. */ 586 587int 588deprecated_pc_in_call_dummy_on_stack (CORE_ADDR pc, CORE_ADDR sp, 589 CORE_ADDR frame_address) 590{ 591 return (INNER_THAN ((sp), (pc)) 592 && (frame_address != 0) 593 && INNER_THAN ((pc), (frame_address))); 594} 595 596int 597deprecated_pc_in_call_dummy_at_entry_point (CORE_ADDR pc, CORE_ADDR sp, 598 CORE_ADDR frame_address) 599{ 600 CORE_ADDR addr = entry_point_address (); 601 return ((pc) >= addr && (pc) <= (addr + DECR_PC_AFTER_BREAK)); 602} 603 604/* Returns true for a user frame or a call_function_by_hand dummy 605 frame, and false for the CRT0 start-up frame. Purpose is to 606 terminate backtrace. */ 607 608int 609legacy_frame_chain_valid (CORE_ADDR fp, struct frame_info *fi) 610{ 611 /* Don't prune CALL_DUMMY frames. */ 612 if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES 613 && DEPRECATED_PC_IN_CALL_DUMMY (get_frame_pc (fi), 0, 0)) 614 return 1; 615 616 /* If the new frame pointer is zero, then it isn't valid. */ 617 if (fp == 0) 618 return 0; 619 620 /* If the new frame would be inside (younger than) the previous frame, 621 then it isn't valid. */ 622 if (INNER_THAN (fp, get_frame_base (fi))) 623 return 0; 624 625 /* If the architecture has a custom DEPRECATED_FRAME_CHAIN_VALID, 626 call it now. */ 627 if (DEPRECATED_FRAME_CHAIN_VALID_P ()) 628 return DEPRECATED_FRAME_CHAIN_VALID (fp, fi); 629 630 /* If we're already inside the entry function for the main objfile, then it 631 isn't valid. */ 632 if (legacy_inside_entry_func (get_frame_pc (fi))) 633 return 0; 634 635 /* If we're inside the entry file, it isn't valid. */ 636 /* NOTE/drow 2002-12-25: should there be a way to disable this check? It 637 assumes a single small entry file, and the way some debug readers (e.g. 638 dbxread) figure out which object is the entry file is somewhat hokey. */ 639 if (deprecated_inside_entry_file (frame_pc_unwind (fi))) 640 return 0; 641 642 return 1; 643} 644