gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004, 2007, 2008, 2009, 2010, 2011
   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 "tramp-frame.h"
  23 #include "frame-unwind.h"
  24 #include "gdbcore.h"
  25 #include "symtab.h"
  26 #include "objfiles.h"
  27 #include "target.h"
  28 #include "trad-frame.h"
  29 #include "frame-base.h"
  30 #include "gdb_assert.h"
  31
  32 struct frame_data
  33 {
  34   const struct tramp_frame *tramp_frame;
  35 };
  36
  37 struct tramp_frame_cache
  38 {
  39   CORE_ADDR func;
  40   const struct tramp_frame *tramp_frame;
  41   struct trad_frame_cache *trad_cache;
  42 };
  43
  44 static struct trad_frame_cache *
  45 tramp_frame_cache (struct frame_info *this_frame,
  46                    void **this_cache)
  47 {
  48   struct tramp_frame_cache *tramp_cache = (*this_cache);
  49
  50   if (tramp_cache->trad_cache == NULL)
  51     {
  52       tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame);
  53       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  54                                       this_frame,
  55                                       tramp_cache->trad_cache,
  56                                       tramp_cache->func);
  57     }
  58   return tramp_cache->trad_cache;
  59 }
  60
  61 static void
  62 tramp_frame_this_id (struct frame_info *this_frame,
  63                      void **this_cache,
  64                      struct frame_id *this_id)
  65 {
  66   struct trad_frame_cache *trad_cache
  67     = tramp_frame_cache (this_frame, this_cache);
  68
  69   trad_frame_get_id (trad_cache, this_id);
  70 }
  71
  72 static struct value *
  73 tramp_frame_prev_register (struct frame_info *this_frame,
  74                            void **this_cache,
  75                            int prev_regnum)
  76 {
  77   struct trad_frame_cache *trad_cache
  78     = tramp_frame_cache (this_frame, this_cache);
  79
  80   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
  81 }
  82
  83 static CORE_ADDR
  84 tramp_frame_start (const struct tramp_frame *tramp,
  85                    struct frame_info *this_frame, CORE_ADDR pc)
  86 {
  87   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  88   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  89   int ti;
  90
  91   /* Search through the trampoline for one that matches the
  92      instruction sequence around PC.  */
  93   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  94     {
  95       CORE_ADDR func = pc - tramp->insn_size * ti;
  96       int i;
  97
  98       for (i = 0; 1; i++)
  99         {
 100           gdb_byte buf[sizeof (tramp->insn[0])];
 101           ULONGEST insn;
 102
 103           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 104             return func;
 105           if (!safe_frame_unwind_memory (this_frame,
 106                                          func + i * tramp->insn_size,
 107                                          buf, tramp->insn_size))
 108             break;
 109           insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
 110           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 111             break;
 112         }
 113     }
 114   /* Trampoline doesn't match.  */
 115   return 0;
 116 }
 117
 118 static int
 119 tramp_frame_sniffer (const struct frame_unwind *self,
 120                      struct frame_info *this_frame,
 121                      void **this_cache)
 122 {
 123   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 124   CORE_ADDR pc = get_frame_pc (this_frame);
 125   CORE_ADDR func;
 126   struct tramp_frame_cache *tramp_cache;
 127
 128   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 129      section, then this is not a trampoline.  However, this assumption is
 130      false on HPUX which has a signal trampoline that has a name; it can
 131      also be false when using an alternative signal stack.  */
 132   func = tramp_frame_start (tramp, this_frame, pc);
 133   if (func == 0)
 134     return 0;
 135   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 136   tramp_cache->func = func;
 137   tramp_cache->tramp_frame = tramp;
 138   (*this_cache) = tramp_cache;
 139   return 1;
 140 }
 141
 142 void
 143 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 144                               const struct tramp_frame *tramp_frame)
 145 {
 146   struct frame_data *data;
 147   struct frame_unwind *unwinder;
 148   int i;
 149
 150   /* Check that the instruction sequence contains a sentinel.  */
 151   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 152     {
 153       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 154         break;
 155     }
 156   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 157   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 158
 159   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 160   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 161
 162   data->tramp_frame = tramp_frame;
 163   unwinder->type = tramp_frame->frame_type;
 164   unwinder->unwind_data = data;
 165   unwinder->sniffer = tramp_frame_sniffer;
 166   unwinder->this_id = tramp_frame_this_id;
 167   unwinder->prev_register = tramp_frame_prev_register;
 168   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 169 }