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