gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004, 2007, 2008 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 *next_frame,
  45                    void **this_cache)
  46 {
  47   CORE_ADDR pc = frame_pc_unwind (next_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 (next_frame);
  52       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  53                                       next_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 *next_frame,
  62                      void **this_cache,
  63                      struct frame_id *this_id)
  64 {
  65   struct trad_frame_cache *trad_cache
  66     = tramp_frame_cache (next_frame, this_cache);
  67   trad_frame_get_id (trad_cache, this_id);
  68 }
  69
  70 static void
  71 tramp_frame_prev_register (struct frame_info *next_frame,
  72                            void **this_cache,
  73                            int prev_regnum,
  74                            int *optimizedp,
  75                            enum lval_type * lvalp,
  76                            CORE_ADDR *addrp,
  77                            int *realnump, gdb_byte *valuep)
  78 {
  79   struct trad_frame_cache *trad_cache
  80     = tramp_frame_cache (next_frame, this_cache);
  81   trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp,
  82                            lvalp, addrp, realnump, valuep);
  83 }
  84
  85 static CORE_ADDR
  86 tramp_frame_start (const struct tramp_frame *tramp,
  87                    struct frame_info *next_frame, CORE_ADDR pc)
  88 {
  89   int ti;
  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       for (i = 0; 1; i++)
  97         {
  98           gdb_byte buf[sizeof (tramp->insn[0])];
  99           ULONGEST insn;
 100           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 101             return func;
 102           if (!safe_frame_unwind_memory (next_frame,
 103                                          func + i * tramp->insn_size,
 104                                          buf, tramp->insn_size))
 105             break;
 106           insn = extract_unsigned_integer (buf, tramp->insn_size);
 107           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 108             break;
 109         }
 110     }
 111   /* Trampoline doesn't match.  */
 112   return 0;
 113 }
 114
 115 static int
 116 tramp_frame_sniffer (const struct frame_unwind *self,
 117                      struct frame_info *next_frame,
 118                      void **this_cache)
 119 {
 120   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 121   CORE_ADDR pc = frame_pc_unwind (next_frame);
 122   CORE_ADDR func;
 123   struct tramp_frame_cache *tramp_cache;
 124
 125   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 126      section, then this is not a trampoline.  However, this assumption is
 127      false on HPUX which has a signal trampoline that has a name; it can
 128      also be false when using an alternative signal stack.  */
 129   func = tramp_frame_start (tramp, next_frame, pc);
 130   if (func == 0)
 131     return 0;
 132   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 133   tramp_cache->func = func;
 134   tramp_cache->tramp_frame = tramp;
 135   (*this_cache) = tramp_cache;
 136   return 1;
 137 }
 138
 139 void
 140 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 141                               const struct tramp_frame *tramp_frame)
 142 {
 143   struct frame_data *data;
 144   struct frame_unwind *unwinder;
 145   int i;
 146
 147   /* Check that the instruction sequence contains a sentinel.  */
 148   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 149     {
 150       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 151         break;
 152     }
 153   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 154   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 155
 156   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 157   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 158
 159   data->tramp_frame = tramp_frame;
 160   unwinder->type = tramp_frame->frame_type;
 161   unwinder->unwind_data = data;
 162   unwinder->sniffer = tramp_frame_sniffer;
 163   unwinder->this_id = tramp_frame_this_id;
 164   unwinder->prev_register = tramp_frame_prev_register;
 165   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 166 }