gdb/frame-unwind.c

   1 /* Definitions for frame unwinder, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2003-2013 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "frame-unwind.h"
  23 #include "dummy-frame.h"
  24 #include "inline-frame.h"
  25 #include "value.h"
  26 #include "regcache.h"
  27 #include "exceptions.h"
  28 #include "gdb_assert.h"
  29 #include "gdb_obstack.h"
  30
  31 static struct gdbarch_data *frame_unwind_data;
  32
  33 struct frame_unwind_table_entry
  34 {
  35   const struct frame_unwind *unwinder;
  36   struct frame_unwind_table_entry *next;
  37 };
  38
  39 struct frame_unwind_table
  40 {
  41   struct frame_unwind_table_entry *list;
  42   /* The head of the OSABI part of the search list.  */
  43   struct frame_unwind_table_entry **osabi_head;
  44 };
  45
  46 static void *
  47 frame_unwind_init (struct obstack *obstack)
  48 {
  49   struct frame_unwind_table *table
  50     = OBSTACK_ZALLOC (obstack, struct frame_unwind_table);
  51
  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,
  57                                       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       volatile struct gdb_exception ex;
 106       int res = 0;
 107
 108       old_cleanup = frame_prepare_for_sniffer (this_frame, entry->unwinder);
 109
 110       TRY_CATCH (ex, RETURN_MASK_ERROR)
 111         {
 112           res = entry->unwinder->sniffer (entry->unwinder, this_frame,
 113                                           this_cache);
 114         }
 115       if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
 116         {
 117           /* This usually means that not even the PC is available,
 118              thus most unwinders aren't able to determine if they're
 119              the best fit.  Keep trying.  Fallback prologue unwinders
 120              should always accept the frame.  */
 121         }
 122       else if (ex.reason < 0)
 123         throw_exception (ex);
 124       else if (res)
 125         {
 126           discard_cleanups (old_cleanup);
 127           return;
 128         }
 129
 130       do_cleanups (old_cleanup);
 131     }
 132   internal_error (__FILE__, __LINE__, _("frame_unwind_find_by_frame failed"));
 133 }
 134
 135 /* A default frame sniffer which always accepts the frame.  Used by
 136    fallback prologue unwinders.  */
 137
 138 int
 139 default_frame_sniffer (const struct frame_unwind *self,
 140                        struct frame_info *this_frame,
 141                        void **this_prologue_cache)
 142 {
 143   return 1;
 144 }
 145
 146 /* A default frame unwinder stop_reason callback that always claims
 147    the frame is unwindable.  */
 148
 149 enum unwind_stop_reason
 150 default_frame_unwind_stop_reason (struct frame_info *this_frame,
 151                                   void **this_cache)
 152 {
 153   return UNWIND_NO_REASON;
 154 }
 155
 156 /* Helper functions for value-based register unwinding.  These return
 157    a (possibly lazy) value of the appropriate type.  */
 158
 159 /* Return a value which indicates that FRAME did not save REGNUM.  */
 160
 161 struct value *
 162 frame_unwind_got_optimized (struct frame_info *frame, int regnum)
 163 {
 164   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 165   struct value *reg_val;
 166
 167   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 168   set_value_optimized_out (reg_val, 1);
 169   return reg_val;
 170 }
 171
 172 /* Return a value which indicates that FRAME copied REGNUM into
 173    register NEW_REGNUM.  */
 174
 175 struct value *
 176 frame_unwind_got_register (struct frame_info *frame,
 177                            int regnum, int new_regnum)
 178 {
 179   return value_of_register_lazy (frame, new_regnum);
 180 }
 181
 182 /* Return a value which indicates that FRAME saved REGNUM in memory at
 183    ADDR.  */
 184
 185 struct value *
 186 frame_unwind_got_memory (struct frame_info *frame, int regnum, CORE_ADDR addr)
 187 {
 188   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 189   struct value *v = value_at_lazy (register_type (gdbarch, regnum), addr);
 190
 191   set_value_stack (v, 1);
 192   return v;
 193 }
 194
 195 /* Return a value which indicates that FRAME's saved version of
 196    REGNUM has a known constant (computed) value of VAL.  */
 197
 198 struct value *
 199 frame_unwind_got_constant (struct frame_info *frame, int regnum,
 200                            ULONGEST val)
 201 {
 202   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 203   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 204   struct value *reg_val;
 205
 206   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 207   store_unsigned_integer (value_contents_writeable (reg_val),
 208                           register_size (gdbarch, regnum), byte_order, val);
 209   return reg_val;
 210 }
 211
 212 struct value *
 213 frame_unwind_got_bytes (struct frame_info *frame, int regnum, gdb_byte *buf)
 214 {
 215   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 216   struct value *reg_val;
 217
 218   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 219   memcpy (value_contents_raw (reg_val), buf, register_size (gdbarch, regnum));
 220   return reg_val;
 221 }
 222
 223 /* Return a value which indicates that FRAME's saved version of REGNUM
 224    has a known constant (computed) value of ADDR.  Convert the
 225    CORE_ADDR to a target address if necessary.  */
 226
 227 struct value *
 228 frame_unwind_got_address (struct frame_info *frame, int regnum,
 229                           CORE_ADDR addr)
 230 {
 231   struct gdbarch *gdbarch = frame_unwind_arch (frame);
 232   struct value *reg_val;
 233
 234   reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
 235   pack_long (value_contents_writeable (reg_val),
 236              register_type (gdbarch, regnum), addr);
 237   return reg_val;
 238 }
 239
 240 /* -Wmissing-prototypes */
 241 extern initialize_file_ftype _initialize_frame_unwind;
 242
 243 void
 244 _initialize_frame_unwind (void)
 245 {
 246   frame_unwind_data = gdbarch_data_register_pre_init (frame_unwind_init);
 247 }