gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004-2015 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
  30 struct frame_data
  31 {
  32   const struct tramp_frame *tramp_frame;
  33 };
  34
  35 struct tramp_frame_cache
  36 {
  37   CORE_ADDR func;
  38   const struct tramp_frame *tramp_frame;
  39   struct trad_frame_cache *trad_cache;
  40 };
  41
  42 static struct trad_frame_cache *
  43 tramp_frame_cache (struct frame_info *this_frame,
  44                    void **this_cache)
  45 {
  46   struct tramp_frame_cache *tramp_cache = (*this_cache);
  47
  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
  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
  78   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
  79 }
  80
  81 static CORE_ADDR
  82 tramp_frame_start (const struct tramp_frame *tramp,
  83                    struct frame_info *this_frame, CORE_ADDR pc)
  84 {
  85   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  86   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  87   int ti;
  88
  89   /* Check if we can use this trampoline.  */
  90   if (tramp->validate && !tramp->validate (tramp, this_frame, &pc))
  91     return 0;
  92
  93   /* Search through the trampoline for one that matches the
  94      instruction sequence around PC.  */
  95   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  96     {
  97       CORE_ADDR func = pc - tramp->insn_size * ti;
  98       int i;
  99
 100       for (i = 0; 1; i++)
 101         {
 102           gdb_byte buf[sizeof (tramp->insn[0])];
 103           ULONGEST insn;
 104
 105           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 106             return func;
 107           if (!safe_frame_unwind_memory (this_frame,
 108                                          func + i * tramp->insn_size,
 109                                          buf, tramp->insn_size))
 110             break;
 111           insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
 112           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 113             break;
 114         }
 115     }
 116   /* Trampoline doesn't match.  */
 117   return 0;
 118 }
 119
 120 static int
 121 tramp_frame_sniffer (const struct frame_unwind *self,
 122                      struct frame_info *this_frame,
 123                      void **this_cache)
 124 {
 125   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 126   CORE_ADDR pc = get_frame_pc (this_frame);
 127   CORE_ADDR func;
 128   struct tramp_frame_cache *tramp_cache;
 129
 130   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 131      section, then this is not a trampoline.  However, this assumption is
 132      false on HPUX which has a signal trampoline that has a name; it can
 133      also be false when using an alternative signal stack.  */
 134   func = tramp_frame_start (tramp, this_frame, pc);
 135   if (func == 0)
 136     return 0;
 137   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 138   tramp_cache->func = func;
 139   tramp_cache->tramp_frame = tramp;
 140   (*this_cache) = tramp_cache;
 141   return 1;
 142 }
 143
 144 void
 145 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 146                               const struct tramp_frame *tramp_frame)
 147 {
 148   struct frame_data *data;
 149   struct frame_unwind *unwinder;
 150   int i;
 151
 152   /* Check that the instruction sequence contains a sentinel.  */
 153   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 154     {
 155       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 156         break;
 157     }
 158   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 159   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 160
 161   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 162   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 163
 164   data->tramp_frame = tramp_frame;
 165   unwinder->type = tramp_frame->frame_type;
 166   unwinder->unwind_data = data;
 167   unwinder->sniffer = tramp_frame_sniffer;
 168   unwinder->stop_reason = default_frame_unwind_stop_reason;
 169   unwinder->this_id = tramp_frame_this_id;
 170   unwinder->prev_register = tramp_frame_prev_register;
 171   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 172 }