gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004, 2007, 2008, 2009 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   CORE_ADDR pc = get_frame_pc (this_frame);
  48   struct tramp_frame_cache *tramp_cache = (*this_cache);
  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   trad_frame_get_id (trad_cache, this_id);
  68 }
  69
  70 static struct value *
  71 tramp_frame_prev_register (struct frame_info *this_frame,
  72                            void **this_cache,
  73                            int prev_regnum)
  74 {
  75   struct trad_frame_cache *trad_cache
  76     = tramp_frame_cache (this_frame, this_cache);
  77   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
  78 }
  79
  80 static CORE_ADDR
  81 tramp_frame_start (const struct tramp_frame *tramp,
  82                    struct frame_info *this_frame, CORE_ADDR pc)
  83 {
  84   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  85   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  86   int ti;
  87   /* Search through the trampoline for one that matches the
  88      instruction sequence around PC.  */
  89   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  90     {
  91       CORE_ADDR func = pc - tramp->insn_size * ti;
  92       int i;
  93       for (i = 0; 1; i++)
  94         {
  95           gdb_byte buf[sizeof (tramp->insn[0])];
  96           ULONGEST insn;
  97           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
  98             return func;
  99           if (!safe_frame_unwind_memory (this_frame,
 100                                          func + i * tramp->insn_size,
 101                                          buf, tramp->insn_size))
 102             break;
 103           insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
 104           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 105             break;
 106         }
 107     }
 108   /* Trampoline doesn't match.  */
 109   return 0;
 110 }
 111
 112 static int
 113 tramp_frame_sniffer (const struct frame_unwind *self,
 114                      struct frame_info *this_frame,
 115                      void **this_cache)
 116 {
 117   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 118   CORE_ADDR pc = get_frame_pc (this_frame);
 119   CORE_ADDR func;
 120   struct tramp_frame_cache *tramp_cache;
 121
 122   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 123      section, then this is not a trampoline.  However, this assumption is
 124      false on HPUX which has a signal trampoline that has a name; it can
 125      also be false when using an alternative signal stack.  */
 126   func = tramp_frame_start (tramp, this_frame, pc);
 127   if (func == 0)
 128     return 0;
 129   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 130   tramp_cache->func = func;
 131   tramp_cache->tramp_frame = tramp;
 132   (*this_cache) = tramp_cache;
 133   return 1;
 134 }
 135
 136 void
 137 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 138                               const struct tramp_frame *tramp_frame)
 139 {
 140   struct frame_data *data;
 141   struct frame_unwind *unwinder;
 142   int i;
 143
 144   /* Check that the instruction sequence contains a sentinel.  */
 145   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 146     {
 147       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 148         break;
 149     }
 150   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 151   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 152
 153   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 154   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 155
 156   data->tramp_frame = tramp_frame;
 157   unwinder->type = tramp_frame->frame_type;
 158   unwinder->unwind_data = data;
 159   unwinder->sniffer = tramp_frame_sniffer;
 160   unwinder->this_id = tramp_frame_this_id;
 161   unwinder->prev_register = tramp_frame_prev_register;
 162   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 163 }