gdb/frame-unwind.c

   1 /* Definitions for frame unwinder, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010, 2011
   4    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 "frame.h"
  23 #include "frame-unwind.h"
  24 #include "dummy-frame.h"
  25 #include "inline-frame.h"
  26 #include "value.h"
  27 #include "regcache.h"
  28
  29 #include "gdb_assert.h"
  30 #include "gdb_obstack.h"
  31
  32 static struct gdbarch_data *frame_unwind_data;
  33
  34 struct frame_unwind_table_entry
  35 {
  36   const struct frame_unwind *unwinder;
  37   struct frame_unwind_table_entry *next;
  38 };
  39
  40 struct frame_unwind_table
  41 {
  42   struct frame_unwind_table_entry *list;
  43   /* The head of the OSABI part of the search list.  */
  44   struct frame_unwind_table_entry **osabi_head;
  45 };
  46
  47 static void *
  48 frame_unwind_init (struct obstack *obstack)
  49 {
  50   struct frame_unwind_table *table
  51     = OBSTACK_ZALLOC (obstack, struct frame_unwind_table);
  52
  53   /* Start the table out with a few default sniffers.  OSABI code
  54      can't override this.  */
  55   table->list = OBSTACK_ZALLOC (obstack, struct frame_unwind_table_entry);
  56   table->list->unwinder = &dummy_frame_unwind;
  57   table->list->next = OBSTACK_ZALLOC (obstack,
  58                                       struct frame_unwind_table_entry);
  59   table->list->next->unwinder = &inline_frame_unwind;
  60   /* The insertion point for OSABI sniffers.  */
  61   table->osabi_head = &table->list->next->next;
  62   return table;
  63 }
  64
  65 void
  66 frame_unwind_prepend_unwinder (struct gdbarch *gdbarch,
  67                                 const struct frame_unwind *unwinder)
  68 {
  69   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  70   struct frame_unwind_table_entry *entry;
  71
  72   /* Insert the new entry at the start of the list.  */
  73   entry = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  74   entry->unwinder = unwinder;
  75   entry->next = (*table->osabi_head);
  76   (*table->osabi_head) = entry;
  77 }
  78
  79 void
  80 frame_unwind_append_unwinder (struct gdbarch *gdbarch,
  81                               const struct frame_unwind *unwinder)
  82 {
  83   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
  84   struct frame_unwind_table_entry **ip;
  85
  86   /* Find the end of the list and insert the new entry there.  */
  87   for (ip = table->osabi_head; (*ip) != NULL; ip = &(*ip)->next);
  88   (*ip) = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind_table_entry);
  89   (*ip)->unwinder = unwinder;
  90 }
  91
  92 /* Iterate through sniffers for THIS_FRAME frame until one returns with an
  93    unwinder implementation.  THIS_FRAME->UNWIND must be NULL, it will get set
  94    by this function.  Possibly initialize THIS_CACHE.  */
  95
  96 void
  97 frame_unwind_find_by_frame (struct frame_info *this_frame, void **this_cache)
  98 {
  99   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 100   struct frame_unwind_table *table = gdbarch_data (gdbarch, frame_unwind_data);
 101   struct frame_unwind_table_entry *entry;
 102
 103   for (entry = table->list; entry != NULL; entry = entry->next)
 104     {
 105       struct cleanup *old_cleanup;
 106
 107       old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder);
 108       if (entry->unwinder->sniffer (entry->unwinder, this_frame,
 109                                     this_cache))
 110         {
 111           discard_cleanups (old_cleanup);
 112           return;
 113         }
 114       do_cleanups (old_cleanup);
 115     }
 116   internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed"));
 117 }
 118
 119 /* A default frame sniffer which always accepts the frame.  Used by
 120    fallback prologue unwinders.  */
 121
 122 int
 123 default_frame_sniffer (const struct frame_unwind *self,
 124                        struct frame_info *this_frame,
 125                        void **this_prologue_cache)
 126 {
 127   return 1;
 128 }
 129
 130 /* Helper functions for value-based register unwinding.  These return
 131    a (possibly lazy) value of the appropriate type.  */
 132
 133 /* Return a value which indicates that FRAME did not save REGNUM.  */
 134
 135 struct value *
 136 frame_unwind_got_optimized (struct frame_info *frame, int regnum)
 137 {
 138   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 139   struct value *reg_val;
 140
 141   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 142   set_value_optimized_out (reg_val, 1);
 143   return reg_val;
 144 }
 145
 146 /* Return a value which indicates that FRAME copied REGNUM into
 147    register NEW_REGNUM.  */
 148
 149 struct value *
 150 frame_unwind_got_register (struct frame_info *frame,
 151                            int regnum, int new_regnum)
 152 {
 153   return value_of_register_lazy (frame, new_regnum);
 154 }
 155
 156 /* Return a value which indicates that FRAME saved REGNUM in memory at
 157    ADDR.  */
 158
 159 struct value *
 160 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr)
 161 {
 162   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 163   struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr);
 164
 165   set_value_stack (v, 1);
 166   return v;
 167 }
 168
 169 /* Return a value which indicates that FRAME's saved version of
 170    REGNUM has a known constant (computed) value of VAL.  */
 171
 172 struct value *
 173 frame_unwind_got_constant (struct frame_info *frame, int regnum,
 174                            ULONGEST val)
 175 {
 176   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 177   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 178   struct value *reg_val;
 179
 180   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 181   store_unsigned_integer (value_contents_writeable (reg_val),
 182                           register_size (gdbarch, regnum), byte_order, val);
 183   return reg_val;
 184 }
 185
 186 struct value *
 187 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf)
 188 {
 189   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 190   struct value *reg_val;
 191
 192   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 193   memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum));
 194   return reg_val;
 195 }
 196
 197 /* Return a value which indicates that FRAME's saved version of REGNUM
 198    has a known constant (computed) value of ADDR.  Convert the
 199    CORE_ADDR to a target address if necessary.  */
 200
 201 struct value *
 202 frame_unwind_got_address (struct frame_info *frame, int regnum,
 203                           CORE_ADDR addr)
 204 {
 205   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 206   struct value *reg_val;
 207
 208   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 209   pack_long (value_contents_writeable (reg_val),
 210              register_type (gdbarch, regnum), addr);
 211   return reg_val;
 212 }
 213
 214 /* -Wmissing-prototypes */
 215 extern initialize_file_ftype _initialize_frame_unwind;
 216
 217 void
 218 _initialize_frame_unwind (void)
 219 {
 220   frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init);
 221 }