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