gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986-2024 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "symtab.h"
  22 #include "bfd.h"
  23 #include "objfiles.h"
  24 #include "frame.h"
  25 #include "gdbcore.h"
  26 #include "value.h"
  27 #include "target.h"
  28 #include "inferior.h"
  29 #include "annotate.h"
  30 #include "regcache.h"
  31 #include "dummy-frame.h"
  32 #include "command.h"
  33 #include "cli/cli-cmds.h"
  34 #include "block.h"
  35 #include "inline-frame.h"
  36
  37 /* Return the innermost lexical block in execution in a specified
  38    stack frame.  The frame address is assumed valid.
  39
  40    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  41    address we used to choose the block.  We use this to find a source
  42    line, to decide which macro definitions are in scope.
  43
  44    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  45    PC, and may not really be a valid PC at all.  For example, in the
  46    caller of a function declared to never return, the code at the
  47    return address will never be reached, so the call instruction may
  48    be the very last instruction in the block.  So the address we use
  49    to choose the block is actually one byte before the return address
  50    --- hopefully pointing us at the call instruction, or its delay
  51    slot instruction.  */
  52
  53 const struct block *
  54 get_frame_block (const frame_info_ptr &frame, CORE_ADDR *addr_in_block)
  55 {
  56   CORE_ADDR pc;
  57   const struct block *bl;
  58   int inline_count;
  59
  60   if (!get_frame_address_in_block_if_available (frame, &pc))
  61     return NULL;
  62
  63   if (addr_in_block)
  64     *addr_in_block = pc;
  65
  66   bl = block_for_pc (pc);
  67   if (bl == NULL)
  68     return NULL;
  69
  70   inline_count = frame_inlined_callees (frame);
  71
  72   while (inline_count > 0)
  73     {
  74       if (bl->inlined_p ())
  75         inline_count--;
  76
  77       bl = bl->superblock ();
  78       gdb_assert (bl != NULL);
  79     }
  80
  81   return bl;
  82 }
  83
  84 CORE_ADDR
  85 get_pc_function_start (CORE_ADDR pc)
  86 {
  87   const struct block *bl;
  88
  89   bl = block_for_pc (pc);
  90   if (bl)
  91     {
  92       struct symbol *symbol = bl->linkage_function ();
  93
  94       if (symbol)
  95         {
  96           bl = symbol->value_block ();
  97           return bl->entry_pc ();
  98         }
  99     }
 100
 101   bound_minimal_symbol msymbol = lookup_minimal_symbol_by_pc (pc);
 102   if (msymbol.minsym)
 103     {
 104       CORE_ADDR fstart = msymbol.value_address ();
 105
 106       if (find_pc_section (fstart))
 107         return fstart;
 108     }
 109
 110   return 0;
 111 }
 112
 113 /* Return the symbol for the function executing in frame FRAME.  */
 114
 115 struct symbol *
 116 get_frame_function (const frame_info_ptr &frame)
 117 {
 118   const struct block *bl = get_frame_block (frame, 0);
 119
 120   if (bl == NULL)
 121     return NULL;
 122
 123   while (bl->function () == NULL && bl->superblock () != NULL)
 124     bl = bl->superblock ();
 125
 126   return bl->function ();
 127 }
 128 \f
 129
 130 /* Return the function containing pc value PC in section SECTION.
 131    Returns 0 if function is not known.  */
 132
 133 struct symbol *
 134 find_pc_sect_function (CORE_ADDR pc, struct obj_section *section)
 135 {
 136   const struct block *b = block_for_pc_sect (pc, section);
 137
 138   if (b == 0)
 139     return 0;
 140   return b->linkage_function ();
 141 }
 142
 143 /* Return the function containing pc value PC.
 144    Returns 0 if function is not known.
 145    Backward compatibility, no section */
 146
 147 struct symbol *
 148 find_pc_function (CORE_ADDR pc)
 149 {
 150   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 151 }
 152
 153 /* See symtab.h.  */
 154
 155 struct symbol *
 156 find_pc_sect_containing_function (CORE_ADDR pc, struct obj_section *section)
 157 {
 158   const block *bl = block_for_pc_sect (pc, section);
 159
 160   if (bl == nullptr)
 161     return nullptr;
 162
 163   return bl->containing_function ();
 164 }
 165
 166 /* These variables are used to cache the most recent result of
 167    find_pc_partial_function.
 168
 169    The addresses cache_pc_function_low and cache_pc_function_high
 170    record the range in which PC was found during the most recent
 171    successful lookup.  When the function occupies a single contiguous
 172    address range, these values correspond to the low and high
 173    addresses of the function.  (The high address is actually one byte
 174    beyond the last byte of the function.)  For a function with more
 175    than one (non-contiguous) range, the range in which PC was found is
 176    used to set the cache bounds.
 177
 178    When determining whether or not these cached values apply to a
 179    particular PC value, PC must be within the range specified by
 180    cache_pc_function_low and cache_pc_function_high.  In addition to
 181    PC being in that range, cache_pc_section must also match PC's
 182    section.  See find_pc_partial_function() for details on both the
 183    comparison as well as how PC's section is determined.
 184
 185    The other values aren't used for determining whether the cache
 186    applies, but are used for setting the outputs from
 187    find_pc_partial_function.  cache_pc_function_low and
 188    cache_pc_function_high are used to set outputs as well.  */
 189
 190 static CORE_ADDR cache_pc_function_low = 0;
 191 static CORE_ADDR cache_pc_function_high = 0;
 192 static const general_symbol_info *cache_pc_function_sym = nullptr;
 193 static struct obj_section *cache_pc_function_section = NULL;
 194 static const struct block *cache_pc_function_block = nullptr;
 195
 196 /* Clear cache, e.g. when symbol table is discarded.  */
 197
 198 void
 199 clear_pc_function_cache (void)
 200 {
 201   cache_pc_function_low = 0;
 202   cache_pc_function_high = 0;
 203   cache_pc_function_sym = nullptr;
 204   cache_pc_function_section = NULL;
 205   cache_pc_function_block = nullptr;
 206 }
 207
 208 /* See symtab.h.  */
 209
 210 bool
 211 find_pc_partial_function_sym (CORE_ADDR pc,
 212                               const struct general_symbol_info **sym,
 213                               CORE_ADDR *address, CORE_ADDR *endaddr,
 214                               const struct block **block)
 215 {
 216   struct obj_section *section;
 217   struct symbol *f;
 218   struct compunit_symtab *compunit_symtab = NULL;
 219   CORE_ADDR mapped_pc;
 220   bound_minimal_symbol msymbol;
 221
 222   /* To ensure that the symbol returned belongs to the correct section
 223      (and that the last [random] symbol from the previous section
 224      isn't returned) try to find the section containing PC.  First try
 225      the overlay code (which by default returns NULL); and second try
 226      the normal section code (which almost always succeeds).  */
 227   section = find_pc_overlay (pc);
 228   if (section == NULL)
 229     section = find_pc_section (pc);
 230
 231   mapped_pc = overlay_mapped_address (pc, section);
 232
 233   if (mapped_pc >= cache_pc_function_low
 234       && mapped_pc < cache_pc_function_high
 235       && section == cache_pc_function_section)
 236     goto return_cached_value;
 237
 238   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 239   compunit_symtab = find_pc_sect_compunit_symtab (mapped_pc, section);
 240
 241   if (compunit_symtab != NULL)
 242     {
 243       /* Checking whether the msymbol has a larger value is for the
 244          "pathological" case mentioned in stack.c:find_frame_funname.
 245
 246          We use BLOCK_ENTRY_PC instead of BLOCK_START_PC for this
 247          comparison because the minimal symbol should refer to the
 248          function's entry pc which is not necessarily the lowest
 249          address of the function.  This will happen when the function
 250          has more than one range and the entry pc is not within the
 251          lowest range of addresses.  */
 252       f = find_pc_sect_function (mapped_pc, section);
 253       if (f != NULL
 254           && (msymbol.minsym == NULL
 255               || (f->value_block ()->entry_pc ()
 256                   >= msymbol.value_address ())))
 257         {
 258           const struct block *b = f->value_block ();
 259
 260           cache_pc_function_sym = f;
 261           cache_pc_function_section = section;
 262           cache_pc_function_block = b;
 263
 264           /* For blocks occupying contiguous addresses (i.e. no gaps),
 265              the low and high cache addresses are simply the start
 266              and end of the block.
 267
 268              For blocks with non-contiguous ranges, we have to search
 269              for the range containing mapped_pc and then use the start
 270              and end of that range.
 271
 272              This causes the returned *ADDRESS and *ENDADDR values to
 273              be limited to the range in which mapped_pc is found.  See
 274              comment preceding declaration of find_pc_partial_function
 275              in symtab.h for more information.  */
 276
 277           if (b->is_contiguous ())
 278             {
 279               cache_pc_function_low = b->start ();
 280               cache_pc_function_high = b->end ();
 281             }
 282           else
 283             {
 284               bool found = false;
 285               for (const blockrange &range : b->ranges ())
 286                 {
 287                   if (range.start () <= mapped_pc && mapped_pc < range.end ())
 288                     {
 289                       cache_pc_function_low = range.start ();
 290                       cache_pc_function_high = range.end ();
 291                       found = true;
 292                       break;
 293                     }
 294                 }
 295               /* Above loop should exit via the break.  */
 296               gdb_assert (found);
 297             }
 298
 299
 300           goto return_cached_value;
 301         }
 302     }
 303
 304   /* Not in the normal symbol tables, see if the pc is in a known
 305      section.  If it's not, then give up.  This ensures that anything
 306      beyond the end of the text seg doesn't appear to be part of the
 307      last function in the text segment.  */
 308
 309   if (!section)
 310     msymbol.minsym = NULL;
 311
 312   /* Must be in the minimal symbol table.  */
 313   if (msymbol.minsym == NULL)
 314     {
 315       /* No available symbol.  */
 316       if (sym != nullptr)
 317         *sym = 0;
 318       if (address != NULL)
 319         *address = 0;
 320       if (endaddr != NULL)
 321         *endaddr = 0;
 322       if (block != nullptr)
 323         *block = nullptr;
 324       return false;
 325     }
 326
 327   cache_pc_function_low = msymbol.value_address ();
 328   cache_pc_function_sym = msymbol.minsym;
 329   cache_pc_function_section = section;
 330   cache_pc_function_high = minimal_symbol_upper_bound (msymbol);
 331   cache_pc_function_block = nullptr;
 332
 333  return_cached_value:
 334
 335   if (address)
 336     {
 337       if (pc_in_unmapped_range (pc, section))
 338         *address = overlay_unmapped_address (cache_pc_function_low, section);
 339       else
 340         *address = cache_pc_function_low;
 341     }
 342
 343   if (sym != nullptr)
 344     *sym = cache_pc_function_sym;
 345
 346   if (endaddr)
 347     {
 348       if (pc_in_unmapped_range (pc, section))
 349         {
 350           /* Because the high address is actually beyond the end of
 351              the function (and therefore possibly beyond the end of
 352              the overlay), we must actually convert (high - 1) and
 353              then add one to that.  */
 354
 355           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 356                                                    section);
 357         }
 358       else
 359         *endaddr = cache_pc_function_high;
 360     }
 361
 362   if (block != nullptr)
 363     *block = cache_pc_function_block;
 364
 365   return true;
 366 }
 367
 368 /* See symtab.h.  */
 369
 370 bool
 371 find_pc_partial_function (CORE_ADDR pc, const char **name, CORE_ADDR *address,
 372                           CORE_ADDR *endaddr, const struct block **block)
 373 {
 374   const general_symbol_info *gsi;
 375   bool r = find_pc_partial_function_sym (pc, &gsi, address, endaddr, block);
 376   if (name != nullptr)
 377     *name = r ? gsi->linkage_name () : nullptr;
 378   return r;
 379 }
 380
 381
 382 /* See symtab.h.  */
 383
 384 bool
 385 find_function_entry_range_from_pc (CORE_ADDR pc, const char **name,
 386                                    CORE_ADDR *address, CORE_ADDR *endaddr)
 387 {
 388   const struct block *block;
 389   bool status = find_pc_partial_function (pc, name, address, endaddr, &block);
 390
 391   if (status && block != nullptr && !block->is_contiguous ())
 392     {
 393       CORE_ADDR entry_pc = block->entry_pc ();
 394
 395       for (const blockrange &range : block->ranges ())
 396         {
 397           if (range.start () <= entry_pc && entry_pc < range.end ())
 398             {
 399               if (address != nullptr)
 400                 *address = range.start ();
 401
 402               if (endaddr != nullptr)
 403                 *endaddr = range.end ();
 404
 405               return status;
 406             }
 407         }
 408
 409       /* It's an internal error if we exit the above loop without finding
 410          the range.  */
 411       internal_error (_("Entry block not found in find_function_entry_range_from_pc"));
 412     }
 413
 414   return status;
 415 }
 416
 417 /* See symtab.h.  */
 418
 419 struct type *
 420 find_function_type (CORE_ADDR pc)
 421 {
 422   struct symbol *sym = find_pc_function (pc);
 423
 424   if (sym != NULL && sym->value_block ()->entry_pc () == pc)
 425     return sym->type ();
 426
 427   return NULL;
 428 }
 429
 430 /* See symtab.h.  */
 431
 432 struct type *
 433 find_gnu_ifunc_target_type (CORE_ADDR resolver_funaddr)
 434 {
 435   struct type *resolver_type = find_function_type (resolver_funaddr);
 436   if (resolver_type != NULL)
 437     {
 438       /* Get the return type of the resolver.  */
 439       struct type *resolver_ret_type
 440         = check_typedef (resolver_type->target_type ());
 441
 442       /* If we found a pointer to function, then the resolved type
 443          is the type of the pointed-to function.  */
 444       if (resolver_ret_type->code () == TYPE_CODE_PTR)
 445         {
 446           struct type *resolved_type
 447             = resolver_ret_type->target_type ();
 448           if (check_typedef (resolved_type)->code () == TYPE_CODE_FUNC)
 449             return resolved_type;
 450         }
 451     }
 452
 453   return NULL;
 454 }
 455
 456 /* Return the innermost stack frame that is executing inside of BLOCK and is
 457    at least as old as the selected frame. Return NULL if there is no
 458    such frame.  If BLOCK is NULL, just return NULL.  */
 459
 460 frame_info_ptr
 461 block_innermost_frame (const struct block *block)
 462 {
 463   if (block == NULL)
 464     return NULL;
 465
 466   frame_info_ptr frame = get_selected_frame ();
 467   while (frame != NULL)
 468     {
 469       const struct block *frame_block = get_frame_block (frame, NULL);
 470       if (frame_block != NULL && block->contains (frame_block))
 471         return frame;
 472
 473       frame = get_prev_frame (frame);
 474     }
 475
 476   return NULL;
 477 }