gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986-2022 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 "defs.h"
  22 #include "symtab.h"
  23 #include "bfd.h"
  24 #include "objfiles.h"
  25 #include "frame.h"
  26 #include "gdbcore.h"
  27 #include "value.h"
  28 #include "target.h"
  29 #include "inferior.h"
  30 #include "annotate.h"
  31 #include "regcache.h"
  32 #include "dummy-frame.h"
  33 #include "command.h"
  34 #include "gdbcmd.h"
  35 #include "block.h"
  36 #include "inline-frame.h"
  37
  38 /* Return the innermost lexical block in execution in a specified
  39    stack frame.  The frame address is assumed valid.
  40
  41    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  42    address we used to choose the block.  We use this to find a source
  43    line, to decide which macro definitions are in scope.
  44
  45    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  46    PC, and may not really be a valid PC at all.  For example, in the
  47    caller of a function declared to never return, the code at the
  48    return address will never be reached, so the call instruction may
  49    be the very last instruction in the block.  So the address we use
  50    to choose the block is actually one byte before the return address
  51    --- hopefully pointing us at the call instruction, or its delay
  52    slot instruction.  */
  53
  54 const struct block *
  55 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
  56 {
  57   CORE_ADDR pc;
  58   const struct block *bl;
  59   int inline_count;
  60
  61   if (!get_frame_address_in_block_if_available (frame, &pc))
  62     return NULL;
  63
  64   if (addr_in_block)
  65     *addr_in_block = pc;
  66
  67   bl = block_for_pc (pc);
  68   if (bl == NULL)
  69     return NULL;
  70
  71   inline_count = frame_inlined_callees (frame);
  72
  73   while (inline_count > 0)
  74     {
  75       if (block_inlined_p (bl))
  76         inline_count--;
  77
  78       bl = bl->superblock ();
  79       gdb_assert (bl != NULL);
  80     }
  81
  82   return bl;
  83 }
  84
  85 CORE_ADDR
  86 get_pc_function_start (CORE_ADDR pc)
  87 {
  88   const struct block *bl;
  89   struct bound_minimal_symbol msymbol;
  90
  91   bl = block_for_pc (pc);
  92   if (bl)
  93     {
  94       struct symbol *symbol = block_linkage_function (bl);
  95
  96       if (symbol)
  97         {
  98           bl = symbol->value_block ();
  99           return bl->entry_pc ();
 100         }
 101     }
 102
 103   msymbol = lookup_minimal_symbol_by_pc (pc);
 104   if (msymbol.minsym)
 105     {
 106       CORE_ADDR fstart = msymbol.value_address ();
 107
 108       if (find_pc_section (fstart))
 109         return fstart;
 110     }
 111
 112   return 0;
 113 }
 114
 115 /* Return the symbol for the function executing in frame FRAME.  */
 116
 117 struct symbol *
 118 get_frame_function (struct frame_info *frame)
 119 {
 120   const struct block *bl = get_frame_block (frame, 0);
 121
 122   if (bl == NULL)
 123     return NULL;
 124
 125   while (bl->function () == NULL && bl->superblock () != NULL)
 126     bl = bl->superblock ();
 127
 128   return bl->function ();
 129 }
 130 \f
 131
 132 /* Return the function containing pc value PC in section SECTION.
 133    Returns 0 if function is not known.  */
 134
 135 struct symbol *
 136 find_pc_sect_function (CORE_ADDR pc, struct obj_section *section)
 137 {
 138   const struct block *b = block_for_pc_sect (pc, section);
 139
 140   if (b == 0)
 141     return 0;
 142   return block_linkage_function (b);
 143 }
 144
 145 /* Return the function containing pc value PC.
 146    Returns 0 if function is not known.
 147    Backward compatibility, no section */
 148
 149 struct symbol *
 150 find_pc_function (CORE_ADDR pc)
 151 {
 152   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 153 }
 154
 155 /* See symtab.h.  */
 156
 157 struct symbol *
 158 find_pc_sect_containing_function (CORE_ADDR pc, struct obj_section *section)
 159 {
 160   const block *bl = block_for_pc_sect (pc, section);
 161
 162   if (bl == nullptr)
 163     return nullptr;
 164
 165   return block_containing_function (bl);
 166 }
 167
 168 /* These variables are used to cache the most recent result of
 169    find_pc_partial_function.
 170
 171    The addresses cache_pc_function_low and cache_pc_function_high
 172    record the range in which PC was found during the most recent
 173    successful lookup.  When the function occupies a single contiguous
 174    address range, these values correspond to the low and high
 175    addresses of the function.  (The high address is actually one byte
 176    beyond the last byte of the function.)  For a function with more
 177    than one (non-contiguous) range, the range in which PC was found is
 178    used to set the cache bounds.
 179
 180    When determining whether or not these cached values apply to a
 181    particular PC value, PC must be within the range specified by
 182    cache_pc_function_low and cache_pc_function_high.  In addition to
 183    PC being in that range, cache_pc_section must also match PC's
 184    section.  See find_pc_partial_function() for details on both the
 185    comparison as well as how PC's section is determined.
 186
 187    The other values aren't used for determining whether the cache
 188    applies, but are used for setting the outputs from
 189    find_pc_partial_function.  cache_pc_function_low and
 190    cache_pc_function_high are used to set outputs as well.  */
 191
 192 static CORE_ADDR cache_pc_function_low = 0;
 193 static CORE_ADDR cache_pc_function_high = 0;
 194 static const general_symbol_info *cache_pc_function_sym = nullptr;
 195 static struct obj_section *cache_pc_function_section = NULL;
 196 static const struct block *cache_pc_function_block = nullptr;
 197
 198 /* Clear cache, e.g. when symbol table is discarded.  */
 199
 200 void
 201 clear_pc_function_cache (void)
 202 {
 203   cache_pc_function_low = 0;
 204   cache_pc_function_high = 0;
 205   cache_pc_function_sym = nullptr;
 206   cache_pc_function_section = NULL;
 207   cache_pc_function_block = nullptr;
 208 }
 209
 210 /* See symtab.h.  */
 211
 212 bool
 213 find_pc_partial_function_sym (CORE_ADDR pc,
 214                               const struct general_symbol_info **sym,
 215                               CORE_ADDR *address, CORE_ADDR *endaddr,
 216                               const struct block **block)
 217 {
 218   struct obj_section *section;
 219   struct symbol *f;
 220   struct bound_minimal_symbol msymbol;
 221   struct compunit_symtab *compunit_symtab = NULL;
 222   CORE_ADDR mapped_pc;
 223
 224   /* To ensure that the symbol returned belongs to the correct section
 225      (and that the last [random] symbol from the previous section
 226      isn't returned) try to find the section containing PC.  First try
 227      the overlay code (which by default returns NULL); and second try
 228      the normal section code (which almost always succeeds).  */
 229   section = find_pc_overlay (pc);
 230   if (section == NULL)
 231     section = find_pc_section (pc);
 232
 233   mapped_pc = overlay_mapped_address (pc, section);
 234
 235   if (mapped_pc >= cache_pc_function_low
 236       && mapped_pc < cache_pc_function_high
 237       && section == cache_pc_function_section)
 238     goto return_cached_value;
 239
 240   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 241   compunit_symtab = find_pc_sect_compunit_symtab (mapped_pc, section);
 242
 243   if (compunit_symtab != NULL)
 244     {
 245       /* Checking whether the msymbol has a larger value is for the
 246          "pathological" case mentioned in stack.c:find_frame_funname.
 247
 248          We use BLOCK_ENTRY_PC instead of BLOCK_START_PC for this
 249          comparison because the minimal symbol should refer to the
 250          function's entry pc which is not necessarily the lowest
 251          address of the function.  This will happen when the function
 252          has more than one range and the entry pc is not within the
 253          lowest range of addresses.  */
 254       f = find_pc_sect_function (mapped_pc, section);
 255       if (f != NULL
 256           && (msymbol.minsym == NULL
 257               || (f->value_block ()->entry_pc ()
 258                   >= msymbol.value_address ())))
 259         {
 260           const struct block *b = f->value_block ();
 261
 262           cache_pc_function_sym = f;
 263           cache_pc_function_section = section;
 264           cache_pc_function_block = b;
 265
 266           /* For blocks occupying contiguous addresses (i.e. no gaps),
 267              the low and high cache addresses are simply the start
 268              and end of the block.
 269
 270              For blocks with non-contiguous ranges, we have to search
 271              for the range containing mapped_pc and then use the start
 272              and end of that range.
 273
 274              This causes the returned *ADDRESS and *ENDADDR values to
 275              be limited to the range in which mapped_pc is found.  See
 276              comment preceding declaration of find_pc_partial_function
 277              in symtab.h for more information.  */
 278
 279           if (b->is_contiguous ())
 280             {
 281               cache_pc_function_low = b->start ();
 282               cache_pc_function_high = b->end ();
 283             }
 284           else
 285             {
 286               bool found = false;
 287               for (const blockrange &range : b->ranges ())
 288                 {
 289                   if (range.start () <= mapped_pc && mapped_pc < range.end ())
 290                     {
 291                       cache_pc_function_low = range.start ();
 292                       cache_pc_function_high = range.end ();
 293                       found = true;
 294                       break;
 295                     }
 296                 }
 297               /* Above loop should exit via the break.  */
 298               gdb_assert (found);
 299             }
 300
 301
 302           goto return_cached_value;
 303         }
 304     }
 305
 306   /* Not in the normal symbol tables, see if the pc is in a known
 307      section.  If it's not, then give up.  This ensures that anything
 308      beyond the end of the text seg doesn't appear to be part of the
 309      last function in the text segment.  */
 310
 311   if (!section)
 312     msymbol.minsym = NULL;
 313
 314   /* Must be in the minimal symbol table.  */
 315   if (msymbol.minsym == NULL)
 316     {
 317       /* No available symbol.  */
 318       if (sym != nullptr)
 319         *sym = 0;
 320       if (address != NULL)
 321         *address = 0;
 322       if (endaddr != NULL)
 323         *endaddr = 0;
 324       if (block != nullptr)
 325         *block = nullptr;
 326       return false;
 327     }
 328
 329   cache_pc_function_low = msymbol.value_address ();
 330   cache_pc_function_sym = msymbol.minsym;
 331   cache_pc_function_section = section;
 332   cache_pc_function_high = minimal_symbol_upper_bound (msymbol);
 333   cache_pc_function_block = nullptr;
 334
 335  return_cached_value:
 336
 337   if (address)
 338     {
 339       if (pc_in_unmapped_range (pc, section))
 340         *address = overlay_unmapped_address (cache_pc_function_low, section);
 341       else
 342         *address = cache_pc_function_low;
 343     }
 344
 345   if (sym != nullptr)
 346     *sym = cache_pc_function_sym;
 347
 348   if (endaddr)
 349     {
 350       if (pc_in_unmapped_range (pc, section))
 351         {
 352           /* Because the high address is actually beyond the end of
 353              the function (and therefore possibly beyond the end of
 354              the overlay), we must actually convert (high - 1) and
 355              then add one to that.  */
 356
 357           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 358                                                    section);
 359         }
 360       else
 361         *endaddr = cache_pc_function_high;
 362     }
 363
 364   if (block != nullptr)
 365     *block = cache_pc_function_block;
 366
 367   return true;
 368 }
 369
 370 /* See symtab.h.  */
 371
 372 bool
 373 find_pc_partial_function (CORE_ADDR pc, const char **name, CORE_ADDR *address,
 374                           CORE_ADDR *endaddr, const struct block **block)
 375 {
 376   const general_symbol_info *gsi;
 377   bool r = find_pc_partial_function_sym (pc, &gsi, address, endaddr, block);
 378   if (name != nullptr)
 379     *name = r ? gsi->linkage_name () : nullptr;
 380   return r;
 381 }
 382
 383
 384 /* See symtab.h.  */
 385
 386 bool
 387 find_function_entry_range_from_pc (CORE_ADDR pc, const char **name,
 388                                    CORE_ADDR *address, CORE_ADDR *endaddr)
 389 {
 390   const struct block *block;
 391   bool status = find_pc_partial_function (pc, name, address, endaddr, &block);
 392
 393   if (status && block != nullptr && !block->is_contiguous ())
 394     {
 395       CORE_ADDR entry_pc = block->entry_pc ();
 396
 397       for (const blockrange &range : block->ranges ())
 398         {
 399           if (range.start () <= entry_pc && entry_pc < range.end ())
 400             {
 401               if (address != nullptr)
 402                 *address = range.start ();
 403
 404               if (endaddr != nullptr)
 405                 *endaddr = range.end ();
 406
 407               return status;
 408             }
 409         }
 410
 411       /* It's an internal error if we exit the above loop without finding
 412          the range.  */
 413       internal_error (__FILE__, __LINE__,
 414                       _("Entry block not found in find_function_entry_range_from_pc"));
 415     }
 416
 417   return status;
 418 }
 419
 420 /* See symtab.h.  */
 421
 422 struct type *
 423 find_function_type (CORE_ADDR pc)
 424 {
 425   struct symbol *sym = find_pc_function (pc);
 426
 427   if (sym != NULL && sym->value_block ()->entry_pc () == pc)
 428     return sym->type ();
 429
 430   return NULL;
 431 }
 432
 433 /* See symtab.h.  */
 434
 435 struct type *
 436 find_gnu_ifunc_target_type (CORE_ADDR resolver_funaddr)
 437 {
 438   struct type *resolver_type = find_function_type (resolver_funaddr);
 439   if (resolver_type != NULL)
 440     {
 441       /* Get the return type of the resolver.  */
 442       struct type *resolver_ret_type
 443         = check_typedef (resolver_type->target_type ());
 444
 445       /* If we found a pointer to function, then the resolved type
 446          is the type of the pointed-to function.  */
 447       if (resolver_ret_type->code () == TYPE_CODE_PTR)
 448         {
 449           struct type *resolved_type
 450             = resolver_ret_type->target_type ();
 451           if (check_typedef (resolved_type)->code () == TYPE_CODE_FUNC)
 452             return resolved_type;
 453         }
 454     }
 455
 456   return NULL;
 457 }
 458
 459 /* Return the innermost stack frame that is executing inside of BLOCK and is
 460    at least as old as the selected frame. Return NULL if there is no
 461    such frame.  If BLOCK is NULL, just return NULL.  */
 462
 463 struct frame_info *
 464 block_innermost_frame (const struct block *block)
 465 {
 466   if (block == NULL)
 467     return NULL;
 468
 469   frame_info *frame = get_selected_frame ();
 470   while (frame != NULL)
 471     {
 472       const struct block *frame_block = get_frame_block (frame, NULL);
 473       if (frame_block != NULL && contained_in (frame_block, block))
 474         return frame;
 475
 476       frame = get_prev_frame (frame);
 477     }
 478
 479   return NULL;
 480 }