gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986-2018 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 = BLOCK_SUPERBLOCK (bl);
  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_BLOCK_VALUE (symbol);
  99           return BLOCK_START (bl);
 100         }
 101     }
 102
 103   msymbol = lookup_minimal_symbol_by_pc (pc);
 104   if (msymbol.minsym)
 105     {
 106       CORE_ADDR fstart = BMSYMBOL_VALUE_ADDRESS (msymbol);
 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 (BLOCK_FUNCTION (bl) == NULL && BLOCK_SUPERBLOCK (bl) != NULL)
 126     bl = BLOCK_SUPERBLOCK (bl);
 127
 128   return BLOCK_FUNCTION (bl);
 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 /* These variables are used to cache the most recent result
 156    of find_pc_partial_function.  */
 157
 158 static CORE_ADDR cache_pc_function_low = 0;
 159 static CORE_ADDR cache_pc_function_high = 0;
 160 static const char *cache_pc_function_name = 0;
 161 static struct obj_section *cache_pc_function_section = NULL;
 162
 163 /* Clear cache, e.g. when symbol table is discarded.  */
 164
 165 void
 166 clear_pc_function_cache (void)
 167 {
 168   cache_pc_function_low = 0;
 169   cache_pc_function_high = 0;
 170   cache_pc_function_name = (char *) 0;
 171   cache_pc_function_section = NULL;
 172 }
 173
 174 /* Finds the "function" (text symbol) that is smaller than PC but
 175    greatest of all of the potential text symbols in SECTION.  Sets
 176    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 177    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 178    function (exclusive), but passing ENDADDR as non-null means that
 179    the function might cause symbols to be read.  This function either
 180    succeeds or fails (not halfway succeeds).  If it succeeds, it sets
 181    *NAME, *ADDRESS, and *ENDADDR to real information and returns 1.
 182    If it fails, it sets *NAME, *ADDRESS and *ENDADDR to zero and
 183    returns 0.  */
 184
 185 /* Backward compatibility, no section argument.  */
 186
 187 int
 188 find_pc_partial_function (CORE_ADDR pc, const char **name, CORE_ADDR *address,
 189                           CORE_ADDR *endaddr)
 190 {
 191   struct obj_section *section;
 192   struct symbol *f;
 193   struct bound_minimal_symbol msymbol;
 194   struct compunit_symtab *compunit_symtab = NULL;
 195   struct objfile *objfile;
 196   CORE_ADDR mapped_pc;
 197
 198   /* To ensure that the symbol returned belongs to the correct setion
 199      (and that the last [random] symbol from the previous section
 200      isn't returned) try to find the section containing PC.  First try
 201      the overlay code (which by default returns NULL); and second try
 202      the normal section code (which almost always succeeds).  */
 203   section = find_pc_overlay (pc);
 204   if (section == NULL)
 205     section = find_pc_section (pc);
 206
 207   mapped_pc = overlay_mapped_address (pc, section);
 208
 209   if (mapped_pc >= cache_pc_function_low
 210       && mapped_pc < cache_pc_function_high
 211       && section == cache_pc_function_section)
 212     goto return_cached_value;
 213
 214   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 215   ALL_OBJFILES (objfile)
 216   {
 217     if (objfile->sf)
 218       {
 219         compunit_symtab
 220           = objfile->sf->qf->find_pc_sect_compunit_symtab (objfile, msymbol,
 221                                                            mapped_pc, section,
 222                                                            0);
 223       }
 224     if (compunit_symtab != NULL)
 225       break;
 226   }
 227
 228   if (compunit_symtab != NULL)
 229     {
 230       /* Checking whether the msymbol has a larger value is for the
 231          "pathological" case mentioned in print_frame_info.  */
 232       f = find_pc_sect_function (mapped_pc, section);
 233       if (f != NULL
 234           && (msymbol.minsym == NULL
 235               || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 236                   >= BMSYMBOL_VALUE_ADDRESS (msymbol))))
 237         {
 238           cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 239           cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 240           cache_pc_function_name = SYMBOL_LINKAGE_NAME (f);
 241           cache_pc_function_section = section;
 242           goto return_cached_value;
 243         }
 244     }
 245
 246   /* Not in the normal symbol tables, see if the pc is in a known
 247      section.  If it's not, then give up.  This ensures that anything
 248      beyond the end of the text seg doesn't appear to be part of the
 249      last function in the text segment.  */
 250
 251   if (!section)
 252     msymbol.minsym = NULL;
 253
 254   /* Must be in the minimal symbol table.  */
 255   if (msymbol.minsym == NULL)
 256     {
 257       /* No available symbol.  */
 258       if (name != NULL)
 259         *name = 0;
 260       if (address != NULL)
 261         *address = 0;
 262       if (endaddr != NULL)
 263         *endaddr = 0;
 264       return 0;
 265     }
 266
 267   cache_pc_function_low = BMSYMBOL_VALUE_ADDRESS (msymbol);
 268   cache_pc_function_name = MSYMBOL_LINKAGE_NAME (msymbol.minsym);
 269   cache_pc_function_section = section;
 270   cache_pc_function_high = minimal_symbol_upper_bound (msymbol);
 271
 272  return_cached_value:
 273
 274   if (address)
 275     {
 276       if (pc_in_unmapped_range (pc, section))
 277         *address = overlay_unmapped_address (cache_pc_function_low, section);
 278       else
 279         *address = cache_pc_function_low;
 280     }
 281
 282   if (name)
 283     *name = cache_pc_function_name;
 284
 285   if (endaddr)
 286     {
 287       if (pc_in_unmapped_range (pc, section))
 288         {
 289           /* Because the high address is actually beyond the end of
 290              the function (and therefore possibly beyond the end of
 291              the overlay), we must actually convert (high - 1) and
 292              then add one to that.  */
 293
 294           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 295                                                    section);
 296         }
 297       else
 298         *endaddr = cache_pc_function_high;
 299     }
 300
 301   return 1;
 302 }
 303
 304 /* See symtab.h.  */
 305
 306 struct type *
 307 find_function_type (CORE_ADDR pc)
 308 {
 309   struct symbol *sym = find_pc_function (pc);
 310
 311   if (sym != NULL && BLOCK_START (SYMBOL_BLOCK_VALUE (sym)) == pc)
 312     return SYMBOL_TYPE (sym);
 313
 314   return NULL;
 315 }
 316
 317 /* See symtab.h.  */
 318
 319 struct type *
 320 find_gnu_ifunc_target_type (CORE_ADDR resolver_funaddr)
 321 {
 322   struct type *resolver_type = find_function_type (resolver_funaddr);
 323   if (resolver_type != NULL)
 324     {
 325       /* Get the return type of the resolver.  */
 326       struct type *resolver_ret_type
 327         = check_typedef (TYPE_TARGET_TYPE (resolver_type));
 328
 329       /* If we found a pointer to function, then the resolved type
 330          is the type of the pointed-to function.  */
 331       if (TYPE_CODE (resolver_ret_type) == TYPE_CODE_PTR)
 332         {
 333           struct type *resolved_type
 334             = TYPE_TARGET_TYPE (resolver_ret_type);
 335           if (TYPE_CODE (check_typedef (resolved_type)) == TYPE_CODE_FUNC)
 336             return resolved_type;
 337         }
 338     }
 339
 340   return NULL;
 341 }
 342
 343 /* Return the innermost stack frame that is executing inside of BLOCK and is
 344    at least as old as the selected frame. Return NULL if there is no
 345    such frame.  If BLOCK is NULL, just return NULL.  */
 346
 347 struct frame_info *
 348 block_innermost_frame (const struct block *block)
 349 {
 350   struct frame_info *frame;
 351
 352   if (block == NULL)
 353     return NULL;
 354
 355   frame = get_selected_frame_if_set ();
 356   if (frame == NULL)
 357     frame = get_current_frame ();
 358   while (frame != NULL)
 359     {
 360       const struct block *frame_block = get_frame_block (frame, NULL);
 361       if (frame_block != NULL && contained_in (frame_block, block))
 362         return frame;
 363
 364       frame = get_prev_frame (frame);
 365     }
 366
 367   return NULL;
 368 }