gdb/blockframe.c

   1 /* Get info from stack frames; convert between frames, blocks,
   2    functions and pc values.
   3
   4    Copyright (C) 1986-2013 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 #include "psymtab.h"
  39
  40 /* Return the innermost lexical block in execution in a specified
  41    stack frame.  The frame address is assumed valid.
  42
  43    If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the exact code
  44    address we used to choose the block.  We use this to find a source
  45    line, to decide which macro definitions are in scope.
  46
  47    The value returned in *ADDR_IN_BLOCK isn't necessarily the frame's
  48    PC, and may not really be a valid PC at all.  For example, in the
  49    caller of a function declared to never return, the code at the
  50    return address will never be reached, so the call instruction may
  51    be the very last instruction in the block.  So the address we use
  52    to choose the block is actually one byte before the return address
  53    --- hopefully pointing us at the call instruction, or its delay
  54    slot instruction.  */
  55
  56 struct block *
  57 get_frame_block (struct frame_info *frame, CORE_ADDR *addr_in_block)
  58 {
  59   CORE_ADDR pc;
  60   struct block *bl;
  61   int inline_count;
  62
  63   if (!get_frame_address_in_block_if_available (frame, &pc))
  64     return NULL;
  65
  66   if (addr_in_block)
  67     *addr_in_block = pc;
  68
  69   bl = block_for_pc (pc);
  70   if (bl == NULL)
  71     return NULL;
  72
  73   inline_count = frame_inlined_callees (frame);
  74
  75   while (inline_count > 0)
  76     {
  77       if (block_inlined_p (bl))
  78         inline_count--;
  79
  80       bl = BLOCK_SUPERBLOCK (bl);
  81       gdb_assert (bl != NULL);
  82     }
  83
  84   return bl;
  85 }
  86
  87 CORE_ADDR
  88 get_pc_function_start (CORE_ADDR pc)
  89 {
  90   struct block *bl;
  91   struct minimal_symbol *msymbol;
  92
  93   bl = block_for_pc (pc);
  94   if (bl)
  95     {
  96       struct symbol *symbol = block_linkage_function (bl);
  97
  98       if (symbol)
  99         {
 100           bl = SYMBOL_BLOCK_VALUE (symbol);
 101           return BLOCK_START (bl);
 102         }
 103     }
 104
 105   msymbol = lookup_minimal_symbol_by_pc (pc);
 106   if (msymbol)
 107     {
 108       CORE_ADDR fstart = SYMBOL_VALUE_ADDRESS (msymbol);
 109
 110       if (find_pc_section (fstart))
 111         return fstart;
 112     }
 113
 114   return 0;
 115 }
 116
 117 /* Return the symbol for the function executing in frame FRAME.  */
 118
 119 struct symbol *
 120 get_frame_function (struct frame_info *frame)
 121 {
 122   struct block *bl = get_frame_block (frame, 0);
 123
 124   if (bl == NULL)
 125     return NULL;
 126
 127   while (BLOCK_FUNCTION (bl) == NULL && BLOCK_SUPERBLOCK (bl) != NULL)
 128     bl = BLOCK_SUPERBLOCK (bl);
 129
 130   return BLOCK_FUNCTION (bl);
 131 }
 132 \f
 133
 134 /* Return the function containing pc value PC in section SECTION.
 135    Returns 0 if function is not known.  */
 136
 137 struct symbol *
 138 find_pc_sect_function (CORE_ADDR pc, struct obj_section *section)
 139 {
 140   struct block *b = block_for_pc_sect (pc, section);
 141
 142   if (b == 0)
 143     return 0;
 144   return block_linkage_function (b);
 145 }
 146
 147 /* Return the function containing pc value PC.
 148    Returns 0 if function is not known.
 149    Backward compatibility, no section */
 150
 151 struct symbol *
 152 find_pc_function (CORE_ADDR pc)
 153 {
 154   return find_pc_sect_function (pc, find_pc_mapped_section (pc));
 155 }
 156
 157 /* These variables are used to cache the most recent result
 158    of find_pc_partial_function.  */
 159
 160 static CORE_ADDR cache_pc_function_low = 0;
 161 static CORE_ADDR cache_pc_function_high = 0;
 162 static const char *cache_pc_function_name = 0;
 163 static struct obj_section *cache_pc_function_section = NULL;
 164 static int cache_pc_function_is_gnu_ifunc = 0;
 165
 166 /* Clear cache, e.g. when symbol table is discarded.  */
 167
 168 void
 169 clear_pc_function_cache (void)
 170 {
 171   cache_pc_function_low = 0;
 172   cache_pc_function_high = 0;
 173   cache_pc_function_name = (char *) 0;
 174   cache_pc_function_section = NULL;
 175   cache_pc_function_is_gnu_ifunc = 0;
 176 }
 177
 178 /* Finds the "function" (text symbol) that is smaller than PC but
 179    greatest of all of the potential text symbols in SECTION.  Sets
 180    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
 181    If ENDADDR is non-null, then set *ENDADDR to be the end of the
 182    function (exclusive), but passing ENDADDR as non-null means that
 183    the function might cause symbols to be read.  If IS_GNU_IFUNC_P is provided
 184    *IS_GNU_IFUNC_P is set to 1 on return if the function is STT_GNU_IFUNC.
 185    This function either succeeds or fails (not halfway succeeds).  If it
 186    succeeds, it sets *NAME, *ADDRESS, and *ENDADDR to real information and
 187    returns 1.  If it fails, it sets *NAME, *ADDRESS, *ENDADDR and
 188    *IS_GNU_IFUNC_P to zero and returns 0.  */
 189
 190 /* Backward compatibility, no section argument.  */
 191
 192 int
 193 find_pc_partial_function_gnu_ifunc (CORE_ADDR pc, const char **name,
 194                                     CORE_ADDR *address, CORE_ADDR *endaddr,
 195                                     int *is_gnu_ifunc_p)
 196 {
 197   struct obj_section *section;
 198   struct symbol *f;
 199   struct minimal_symbol *msymbol;
 200   struct symtab *symtab = NULL;
 201   struct objfile *objfile;
 202   int i;
 203   CORE_ADDR mapped_pc;
 204
 205   /* To ensure that the symbol returned belongs to the correct setion
 206      (and that the last [random] symbol from the previous section
 207      isn't returned) try to find the section containing PC.  First try
 208      the overlay code (which by default returns NULL); and second try
 209      the normal section code (which almost always succeeds).  */
 210   section = find_pc_overlay (pc);
 211   if (section == NULL)
 212     section = find_pc_section (pc);
 213
 214   mapped_pc = overlay_mapped_address (pc, section);
 215
 216   if (mapped_pc >= cache_pc_function_low
 217       && mapped_pc < cache_pc_function_high
 218       && section == cache_pc_function_section)
 219     goto return_cached_value;
 220
 221   msymbol = lookup_minimal_symbol_by_pc_section (mapped_pc, section);
 222   ALL_OBJFILES (objfile)
 223   {
 224     if (objfile->sf)
 225       symtab = objfile->sf->qf->find_pc_sect_symtab (objfile, msymbol,
 226                                                      mapped_pc, section, 0);
 227     if (symtab)
 228       break;
 229   }
 230
 231   if (symtab)
 232     {
 233       /* Checking whether the msymbol has a larger value is for the
 234          "pathological" case mentioned in print_frame_info.  */
 235       f = find_pc_sect_function (mapped_pc, section);
 236       if (f != NULL
 237           && (msymbol == NULL
 238               || (BLOCK_START (SYMBOL_BLOCK_VALUE (f))
 239                   >= SYMBOL_VALUE_ADDRESS (msymbol))))
 240         {
 241           cache_pc_function_low = BLOCK_START (SYMBOL_BLOCK_VALUE (f));
 242           cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
 243           cache_pc_function_name = SYMBOL_LINKAGE_NAME (f);
 244           cache_pc_function_section = section;
 245           cache_pc_function_is_gnu_ifunc = TYPE_GNU_IFUNC (SYMBOL_TYPE (f));
 246           goto return_cached_value;
 247         }
 248     }
 249
 250   /* Not in the normal symbol tables, see if the pc is in a known
 251      section.  If it's not, then give up.  This ensures that anything
 252      beyond the end of the text seg doesn't appear to be part of the
 253      last function in the text segment.  */
 254
 255   if (!section)
 256     msymbol = NULL;
 257
 258   /* Must be in the minimal symbol table.  */
 259   if (msymbol == NULL)
 260     {
 261       /* No available symbol.  */
 262       if (name != NULL)
 263         *name = 0;
 264       if (address != NULL)
 265         *address = 0;
 266       if (endaddr != NULL)
 267         *endaddr = 0;
 268       if (is_gnu_ifunc_p != NULL)
 269         *is_gnu_ifunc_p = 0;
 270       return 0;
 271     }
 272
 273   cache_pc_function_low = SYMBOL_VALUE_ADDRESS (msymbol);
 274   cache_pc_function_name = SYMBOL_LINKAGE_NAME (msymbol);
 275   cache_pc_function_section = section;
 276   cache_pc_function_is_gnu_ifunc = MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc;
 277
 278   /* If the minimal symbol has a size, use it for the cache.
 279      Otherwise use the lesser of the next minimal symbol in the same
 280      section, or the end of the section, as the end of the
 281      function.  */
 282
 283   if (MSYMBOL_SIZE (msymbol) != 0)
 284     cache_pc_function_high = cache_pc_function_low + MSYMBOL_SIZE (msymbol);
 285   else
 286     {
 287       /* Step over other symbols at this same address, and symbols in
 288          other sections, to find the next symbol in this section with
 289          a different address.  */
 290
 291       for (i = 1; SYMBOL_LINKAGE_NAME (msymbol + i) != NULL; i++)
 292         {
 293           if (SYMBOL_VALUE_ADDRESS (msymbol + i)
 294               != SYMBOL_VALUE_ADDRESS (msymbol)
 295               && SYMBOL_OBJ_SECTION (msymbol + i)
 296               == SYMBOL_OBJ_SECTION (msymbol))
 297             break;
 298         }
 299
 300       if (SYMBOL_LINKAGE_NAME (msymbol + i) != NULL
 301           && SYMBOL_VALUE_ADDRESS (msymbol + i)
 302           < obj_section_endaddr (section))
 303         cache_pc_function_high = SYMBOL_VALUE_ADDRESS (msymbol + i);
 304       else
 305         /* We got the start address from the last msymbol in the objfile.
 306            So the end address is the end of the section.  */
 307         cache_pc_function_high = obj_section_endaddr (section);
 308     }
 309
 310  return_cached_value:
 311
 312   if (address)
 313     {
 314       if (pc_in_unmapped_range (pc, section))
 315         *address = overlay_unmapped_address (cache_pc_function_low, section);
 316       else
 317         *address = cache_pc_function_low;
 318     }
 319
 320   if (name)
 321     *name = cache_pc_function_name;
 322
 323   if (endaddr)
 324     {
 325       if (pc_in_unmapped_range (pc, section))
 326         {
 327           /* Because the high address is actually beyond the end of
 328              the function (and therefore possibly beyond the end of
 329              the overlay), we must actually convert (high - 1) and
 330              then add one to that.  */
 331
 332           *endaddr = 1 + overlay_unmapped_address (cache_pc_function_high - 1,
 333                                                    section);
 334         }
 335       else
 336         *endaddr = cache_pc_function_high;
 337     }
 338
 339   if (is_gnu_ifunc_p)
 340     *is_gnu_ifunc_p = cache_pc_function_is_gnu_ifunc;
 341
 342   return 1;
 343 }
 344
 345 /* See find_pc_partial_function_gnu_ifunc, only the IS_GNU_IFUNC_P parameter
 346    is omitted here for backward API compatibility.  */
 347
 348 int
 349 find_pc_partial_function (CORE_ADDR pc, const char **name, CORE_ADDR *address,
 350                           CORE_ADDR *endaddr)
 351 {
 352   return find_pc_partial_function_gnu_ifunc (pc, name, address, endaddr, NULL);
 353 }
 354
 355 /* Return the innermost stack frame that is executing inside of BLOCK and is
 356    at least as old as the selected frame. Return NULL if there is no
 357    such frame.  If BLOCK is NULL, just return NULL.  */
 358
 359 struct frame_info *
 360 block_innermost_frame (const struct block *block)
 361 {
 362   struct frame_info *frame;
 363
 364   if (block == NULL)
 365     return NULL;
 366
 367   frame = get_selected_frame_if_set ();
 368   if (frame == NULL)
 369     frame = get_current_frame ();
 370   while (frame != NULL)
 371     {
 372       struct block *frame_block = get_frame_block (frame, NULL);
 373       if (frame_block != NULL && contained_in (frame_block, block))
 374         return frame;
 375
 376       frame = get_prev_frame (frame);
 377     }
 378
 379   return NULL;
 380 }