gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004, 2007, 2008, 2009, 2010 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 "tramp-frame.h"
  22 #include "frame-unwind.h"
  23 #include "gdbcore.h"
  24 #include "symtab.h"
  25 #include "objfiles.h"
  26 #include "target.h"
  27 #include "trad-frame.h"
  28 #include "frame-base.h"
  29 #include "gdb_assert.h"
  30
  31 struct frame_data
  32 {
  33   const struct tramp_frame *tramp_frame;
  34 };
  35
  36 struct tramp_frame_cache
  37 {
  38   CORE_ADDR func;
  39   const struct tramp_frame *tramp_frame;
  40   struct trad_frame_cache *trad_cache;
  41 };
  42
  43 static struct trad_frame_cache *
  44 tramp_frame_cache (struct frame_info *this_frame,
  45                    void **this_cache)
  46 {
  47   struct tramp_frame_cache *tramp_cache = (*this_cache);
  48
  49   if (tramp_cache->trad_cache == NULL)
  50     {
  51       tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame);
  52       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  53                                       this_frame,
  54                                       tramp_cache->trad_cache,
  55                                       tramp_cache->func);
  56     }
  57   return tramp_cache->trad_cache;
  58 }
  59
  60 static void
  61 tramp_frame_this_id (struct frame_info *this_frame,
  62                      void **this_cache,
  63                      struct frame_id *this_id)
  64 {
  65   struct trad_frame_cache *trad_cache
  66     = tramp_frame_cache (this_frame, this_cache);
  67
  68   trad_frame_get_id (trad_cache, this_id);
  69 }
  70
  71 static struct value *
  72 tramp_frame_prev_register (struct frame_info *this_frame,
  73                            void **this_cache,
  74                            int prev_regnum)
  75 {
  76   struct trad_frame_cache *trad_cache
  77     = tramp_frame_cache (this_frame, this_cache);
  78
  79   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
  80 }
  81
  82 static CORE_ADDR
  83 tramp_frame_start (const struct tramp_frame *tramp,
  84                    struct frame_info *this_frame, CORE_ADDR pc)
  85 {
  86   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  87   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  88   int ti;
  89
  90   /* Search through the trampoline for one that matches the
  91      instruction sequence around PC.  */
  92   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  93     {
  94       CORE_ADDR func = pc - tramp->insn_size * ti;
  95       int i;
  96
  97       for (i = 0; 1; i++)
  98         {
  99           gdb_byte buf[sizeof (tramp->insn[0])];
 100           ULONGEST insn;
 101
 102           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 103             return func;
 104           if (!safe_frame_unwind_memory (this_frame,
 105                                          func + i * tramp->insn_size,
 106                                          buf, tramp->insn_size))
 107             break;
 108           insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
 109           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 110             break;
 111         }
 112     }
 113   /* Trampoline doesn't match.  */
 114   return 0;
 115 }
 116
 117 static int
 118 tramp_frame_sniffer (const struct frame_unwind *self,
 119                      struct frame_info *this_frame,
 120                      void **this_cache)
 121 {
 122   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 123   CORE_ADDR pc = get_frame_pc (this_frame);
 124   CORE_ADDR func;
 125   struct tramp_frame_cache *tramp_cache;
 126
 127   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 128      section, then this is not a trampoline.  However, this assumption is
 129      false on HPUX which has a signal trampoline that has a name; it can
 130      also be false when using an alternative signal stack.  */
 131   func = tramp_frame_start (tramp, this_frame, pc);
 132   if (func == 0)
 133     return 0;
 134   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 135   tramp_cache->func = func;
 136   tramp_cache->tramp_frame = tramp;
 137   (*this_cache) = tramp_cache;
 138   return 1;
 139 }
 140
 141 void
 142 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 143                               const struct tramp_frame *tramp_frame)
 144 {
 145   struct frame_data *data;
 146   struct frame_unwind *unwinder;
 147   int i;
 148
 149   /* Check that the instruction sequence contains a sentinel.  */
 150   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 151     {
 152       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 153         break;
 154     }
 155   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 156   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 157
 158   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 159   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 160
 161   data->tramp_frame = tramp_frame;
 162   unwinder->type = tramp_frame->frame_type;
 163   unwinder->unwind_data = data;
 164   unwinder->sniffer = tramp_frame_sniffer;
 165   unwinder->this_id = tramp_frame_this_id;
 166   unwinder->prev_register = tramp_frame_prev_register;
 167   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 168 }