gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright 2004 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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "tramp-frame.h"
  24 #include "frame-unwind.h"
  25 #include "gdbcore.h"
  26 #include "symtab.h"
  27 #include "objfiles.h"
  28 #include "target.h"
  29 #include "trad-frame.h"
  30 #include "frame-base.h"
  31 #include "gdb_assert.h"
  32
  33 struct frame_data
  34 {
  35   const struct tramp_frame *tramp_frame;
  36 };
  37
  38 struct tramp_frame_cache
  39 {
  40   CORE_ADDR func;
  41   const struct tramp_frame *tramp_frame;
  42   struct trad_frame_cache *trad_cache;
  43 };
  44
  45 static struct trad_frame_cache *
  46 tramp_frame_cache (struct frame_info *next_frame,
  47                    void **this_cache)
  48 {
  49   CORE_ADDR pc = frame_pc_unwind (next_frame);
  50   struct tramp_frame_cache *tramp_cache = (*this_cache);
  51   if (tramp_cache->trad_cache == NULL)
  52     {
  53       tramp_cache->trad_cache = trad_frame_cache_zalloc (next_frame);
  54       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  55                                       next_frame,
  56                                       tramp_cache->trad_cache,
  57                                       tramp_cache->func);
  58     }
  59   return tramp_cache->trad_cache;
  60 }
  61
  62 static void
  63 tramp_frame_this_id (struct frame_info *next_frame,
  64                      void **this_cache,
  65                      struct frame_id *this_id)
  66 {
  67   struct trad_frame_cache *trad_cache
  68     = tramp_frame_cache (next_frame, this_cache);
  69   trad_frame_get_id (trad_cache, this_id);
  70 }
  71
  72 static void
  73 tramp_frame_prev_register (struct frame_info *next_frame,
  74                            void **this_cache,
  75                            int prev_regnum,
  76                            int *optimizedp,
  77                            enum lval_type * lvalp,
  78                            CORE_ADDR *addrp,
  79                            int *realnump, void *valuep)
  80 {
  81   struct trad_frame_cache *trad_cache
  82     = tramp_frame_cache (next_frame, this_cache);
  83   trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp,
  84                            lvalp, addrp, realnump, valuep);
  85 }
  86
  87 static CORE_ADDR
  88 tramp_frame_start (const struct tramp_frame *tramp,
  89                    struct frame_info *next_frame, CORE_ADDR pc)
  90 {
  91   int ti;
  92   /* Search through the trampoline for one that matches the
  93      instruction sequence around PC.  */
  94   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  95     {
  96       CORE_ADDR func = pc - tramp->insn_size * ti;
  97       int i;
  98       for (i = 0; 1; i++)
  99         {
 100           bfd_byte buf[sizeof (tramp->insn[0])];
 101           ULONGEST insn;
 102           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 103             return func;
 104           if (!safe_frame_unwind_memory (next_frame,
 105                                          func + i * tramp->insn_size,
 106                                          buf, tramp->insn_size))
 107             break;
 108           insn = extract_unsigned_integer (buf, tramp->insn_size);
 109           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 110             break;
 111         }
 112     }
 113   /* Trampoline doesn't match.  */
 114   return 0;
 115 }
 116
 117 static int
 118 tramp_frame_sniffer (const struct frame_unwind *self,
 119                      struct frame_info *next_frame,
 120                      void **this_cache)
 121 {
 122   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 123   CORE_ADDR pc = frame_pc_unwind (next_frame);
 124   CORE_ADDR func;
 125   char *name;
 126   struct tramp_frame_cache *tramp_cache;
 127
 128   /* If the function has a valid symbol name, it isn't a
 129      trampoline.  */
 130   find_pc_partial_function (pc, &name, NULL, NULL);
 131   if (name != NULL)
 132     return 0;
 133   /* If the function lives in a valid section (even without a starting
 134      point) it isn't a trampoline.  */
 135   if (find_pc_section (pc) != NULL)
 136     return 0;
 137   /* Finally, check that the trampoline matches at PC.  */
 138   func = tramp_frame_start (tramp, next_frame, pc);
 139   if (func == 0)
 140     return 0;
 141   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 142   tramp_cache->func = func;
 143   tramp_cache->tramp_frame = tramp;
 144   (*this_cache) = tramp_cache;
 145   return 1;
 146 }
 147
 148 void
 149 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 150                               const struct tramp_frame *tramp_frame)
 151 {
 152   struct frame_data *data;
 153   struct frame_unwind *unwinder;
 154   int i;
 155
 156   /* Check that the instruction sequence contains a sentinel.  */
 157   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 158     {
 159       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 160         break;
 161     }
 162   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 163   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 164
 165   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 166   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 167
 168   data->tramp_frame = tramp_frame;
 169   unwinder->type = SIGTRAMP_FRAME;
 170   unwinder->unwind_data = data;
 171   unwinder->sniffer = tramp_frame_sniffer;
 172   unwinder->this_id = tramp_frame_this_id;
 173   unwinder->prev_register = tramp_frame_prev_register;
 174   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 175 }