gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986-2014 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 "gdb_assert.h"
  33 #include "dummy-frame.h"
  34 #include "command.h"
  35 #include "gdbcmd.h"
  36 #include "block.h"
  37 #include "inline-frame.h"
  38
  39 /* Return the innermost lexical block in execution in a specified
  40    stack frame.  The frame address is assumed valid.
  41
  42    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  43    address we used to choose the block.  We use this to find a source
  44    line, to decide which macro definitions are in scope.
  45
  46    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  47    PC, and may not really be a valid PC at all.  For example, in the
  48    caller of a function declared to never return, the code at the
  49    return address will never be reached, so the call instruction may
  50    be the very last instruction in the block.  So the address we use
  51    to choose the block is actually one byte before the return address
  52    --- hopefully pointing us at the call instruction, or its delay
  53    slot instruction.  */
  54
  55 struct block *
  56 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
  57 {
  58   CORE_ADDR pc;
  59   struct block *bl;
  60   int inline_count;
  61
  62   if (!get_frame_address_in_block_if_available (frame, &pc))
  63     return NULL;
  64
  65   if (addr_in_block)
  66     *addr_in_block = pc;
  67
  68   bl = block_for_pc (pc);
  69   if (bl == NULL)
  70     return NULL;
  71
  72   inline_count = frame_inlined_callees (frame);
  73
  74   while (inline_count > 0)
  75     {
  76       if (block_inlined_p (bl))
  77         inline_count--;
  78
  79       bl = BLOCK_SUPERBLOCK (bl);
  80       gdb_assert (bl != NULL);
  81     }
  82
  83   return bl;
  84 }
  85
  86 CORE_ADDR
  87 get_pc_function_start (CORE_ADDR pc)
  88 {
  89   struct block *bl;
  90   struct bound_minimal_symbol msymbol;
  91
  92   bl = block_for_pc (pc);
  93   if (bl)
  94     {
  95       struct symbol *symbol = block_linkage_function (bl);
  96
  97       if (symbol)
  98         {
  99           bl = SYMBOL_BLOCK_VALUE (symbol);
 100           return BLOCK_START (bl);
 101         }
 102     }
 103
 104   msymbol = lookup_minimal_symbol_by_pc (pc);
 105   if (msymbol.minsym)
 106     {
 107       CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol.minsym);
 108
 109       if (find_pc_section (fstart))
 110         return fstart;
 111     }
 112
 113   return 0;
 114 }
 115
 116 /* Return the symbol for the function executing in frame FRAME.  */
 117
 118 struct symbol *
 119 get_frame_function (struct frame_info *frame)
 120 {
 121   struct block *bl = get_frame_block (frame, 0);
 122
 123   if (bl == NULL)
 124     return NULL;
 125
 126   while (BLOCK_FUNCTION (bl) == NULL && BLOCK_SUPERBLOCK (bl) != NULL)
 127     bl = BLOCK_SUPERBLOCK (bl);
 128
 129   return BLOCK_FUNCTION (bl);
 130 }
 131 \f
 132
 133 /* Return the function containing pc value PC in section SECTION.
 134    Returns 0 if function is not known.  */
 135
 136 struct symbol *
 137 find_pc_sect_function (CORE_ADDR pc, struct obj_section *section)
 138 {
 139   struct block *b = block_for_pc_sect (pc, section);
 140
 141   if (b == 0)
 142     return 0;
 143   return block_linkage_function (b);
 144 }
 145
 146 /* Return the function containing pc value PC.
 147    Returns 0 if function is not known.
 148    Backward compatibility, no section */
 149
 150 struct symbol *
 151 find_pc_function (CORE_ADDR pc)
 152 {
 153   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 154 }
 155
 156 /* These variables are used to cache the most recent result
 157    of find_pc_partial_function.  */
 158
 159 static CORE_ADDR cache_pc_function_low = 0;
 160 static CORE_ADDR cache_pc_function_high = 0;
 161 static const char *cache_pc_function_name = 0;
 162 static struct obj_section *cache_pc_function_section = NULL;
 163 static int cache_pc_function_is_gnu_ifunc = 0;
 164
 165 /* Clear cache, e.g. when symbol table is discarded.  */
 166
 167 void
 168 clear_pc_function_cache (void)
 169 {
 170   cache_pc_function_low = 0;
 171   cache_pc_function_high = 0;
 172   cache_pc_function_name = (char *) 0;
 173   cache_pc_function_section = NULL;
 174   cache_pc_function_is_gnu_ifunc = 0;
 175 }
 176
 177 /* Finds the "function" (text symbol) that is smaller than PC but
 178    greatest of all of the potential text symbols in SECTION.  Sets
 179    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 180    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 181    function (exclusive), but passing ENDADDR as non-null means that
 182    the function might cause symbols to be read.  If IS_GNU_IFUNC_P is provided
 183    *IS_GNU_IFUNC_P is set to 1 on return if the function is STT_GNU_IFUNC.
 184    This function either succeeds or fails (not halfway succeeds).  If it
 185    succeeds, it sets *NAME, *ADDRESS, and *ENDADDR to real information and
 186    returns 1.  If it fails, it sets *NAME, *ADDRESS, *ENDADDR and
 187    *IS_GNU_IFUNC_P to zero and returns 0.  */
 188
 189 /* Backward compatibility, no section argument.  */
 190
 191 int
 192 find_pc_partial_function_gnu_ifunc (CORE_ADDR pc, const char **name,
 193                                     CORE_ADDR *address, CORE_ADDR *endaddr,
 194                                     int *is_gnu_ifunc_p)
 195 {
 196   struct obj_section *section;
 197   struct symbol *f;
 198   struct bound_minimal_symbol msymbol;
 199   struct symtab *symtab = NULL;
 200   struct objfile *objfile;
 201   int i;
 202   CORE_ADDR mapped_pc;
 203
 204   /* To ensure that the symbol returned belongs to the correct setion
 205      (and that the last [random] symbol from the previous section
 206      isn't returned) try to find the section containing PC.  First try
 207      the overlay code (which by default returns NULL); and second try
 208      the normal section code (which almost always succeeds).  */
 209   section = find_pc_overlay (pc);
 210   if (section == NULL)
 211     section = find_pc_section (pc);
 212
 213   mapped_pc = overlay_mapped_address (pc, section);
 214
 215   if (mapped_pc >= cache_pc_function_low
 216       && mapped_pc < cache_pc_function_high
 217       && section == cache_pc_function_section)
 218     goto return_cached_value;
 219
 220   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 221   ALL_OBJFILES (objfile)
 222   {
 223     if (objfile->sf)
 224       symtab = objfile->sf->qf->find_pc_sect_symtab (objfile, msymbol.minsym,
 225                                                      mapped_pc, section, 0);
 226     if (symtab)
 227       break;
 228   }
 229
 230   if (symtab)
 231     {
 232       /* Checking whether the msymbol has a larger value is for the
 233          "pathological" case mentioned in print_frame_info.  */
 234       f = find_pc_sect_function (mapped_pc, section);
 235       if (f != NULL
 236           && (msymbol.minsym == NULL
 237               || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 238                   >= SYMBOL_VALUE_ADDRESS (msymbol.minsym))))
 239         {
 240           cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 241           cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 242           cache_pc_function_name = SYMBOL_LINKAGE_NAME (f);
 243           cache_pc_function_section = section;
 244           cache_pc_function_is_gnu_ifunc = TYPE_GNU_IFUNC (SYMBOL_TYPE (f));
 245           goto return_cached_value;
 246         }
 247     }
 248
 249   /* Not in the normal symbol tables, see if the pc is in a known
 250      section.  If it's not, then give up.  This ensures that anything
 251      beyond the end of the text seg doesn't appear to be part of the
 252      last function in the text segment.  */
 253
 254   if (!section)
 255     msymbol.minsym = NULL;
 256
 257   /* Must be in the minimal symbol table.  */
 258   if (msymbol.minsym == NULL)
 259     {
 260       /* No available symbol.  */
 261       if (name != NULL)
 262         *name = 0;
 263       if (address != NULL)
 264         *address = 0;
 265       if (endaddr != NULL)
 266         *endaddr = 0;
 267       if (is_gnu_ifunc_p != NULL)
 268         *is_gnu_ifunc_p = 0;
 269       return 0;
 270     }
 271
 272   cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol.minsym);
 273   cache_pc_function_name = SYMBOL_LINKAGE_NAME (msymbol.minsym);
 274   cache_pc_function_section = section;
 275   cache_pc_function_is_gnu_ifunc = (MSYMBOL_TYPE (msymbol.minsym)
 276                                     == mst_text_gnu_ifunc);
 277   cache_pc_function_high = minimal_symbol_upper_bound (msymbol);
 278
 279  return_cached_value:
 280
 281   if (address)
 282     {
 283       if (pc_in_unmapped_range (pc, section))
 284         *address = overlay_unmapped_address (cache_pc_function_low, section);
 285       else
 286         *address = cache_pc_function_low;
 287     }
 288
 289   if (name)
 290     *name = cache_pc_function_name;
 291
 292   if (endaddr)
 293     {
 294       if (pc_in_unmapped_range (pc, section))
 295         {
 296           /* Because the high address is actually beyond the end of
 297              the function (and therefore possibly beyond the end of
 298              the overlay), we must actually convert (high - 1) and
 299              then add one to that.  */
 300
 301           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 302                                                    section);
 303         }
 304       else
 305         *endaddr = cache_pc_function_high;
 306     }
 307
 308   if (is_gnu_ifunc_p)
 309     *is_gnu_ifunc_p = cache_pc_function_is_gnu_ifunc;
 310
 311   return 1;
 312 }
 313
 314 /* See find_pc_partial_function_gnu_ifunc, only the IS_GNU_IFUNC_P parameter
 315    is omitted here for backward API compatibility.  */
 316
 317 int
 318 find_pc_partial_function (CORE_ADDR pc, const char **name, CORE_ADDR *address,
 319                           CORE_ADDR *endaddr)
 320 {
 321   return find_pc_partial_function_gnu_ifunc (pc, name, address, endaddr, NULL);
 322 }
 323
 324 /* Return the innermost stack frame that is executing inside of BLOCK and is
 325    at least as old as the selected frame. Return NULL if there is no
 326    such frame.  If BLOCK is NULL, just return NULL.  */
 327
 328 struct frame_info *
 329 block_innermost_frame (const struct block *block)
 330 {
 331   struct frame_info *frame;
 332
 333   if (block == NULL)
 334     return NULL;
 335
 336   frame = get_selected_frame_if_set ();
 337   if (frame == NULL)
 338     frame = get_current_frame ();
 339   while (frame != NULL)
 340     {
 341       struct block *frame_block = get_frame_block (frame, NULL);
 342       if (frame_block != NULL && contained_in (frame_block, block))
 343         return frame;
 344
 345       frame = get_prev_frame (frame);
 346     }
 347
 348   return NULL;
 349 }