gdb/frame-unwind.c

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