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
  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 *next_frame,
  46                    void **this_cache)
  47 {
  48   CORE_ADDR pc = frame_pc_unwind (next_frame);
  49   struct tramp_frame_cache *tramp_cache = (*this_cache);
  50   if (tramp_cache->trad_cache == NULL)
  51     {
  52       tramp_cache->trad_cache = trad_frame_cache_zalloc (next_frame);
  53       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  54                                       next_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 *next_frame,
  63                      void **this_cache,
  64                      struct frame_id *this_id)
  65 {
  66   struct trad_frame_cache *trad_cache
  67     = tramp_frame_cache (next_frame, this_cache);
  68   trad_frame_get_id (trad_cache, this_id);
  69 }
  70
  71 static void
  72 tramp_frame_prev_register (struct frame_info *next_frame,
  73                            void **this_cache,
  74                            int prev_regnum,
  75                            int *optimizedp,
  76                            enum lval_type * lvalp,
  77                            CORE_ADDR *addrp,
  78                            int *realnump, void *valuep)
  79 {
  80   struct trad_frame_cache *trad_cache
  81     = tramp_frame_cache (next_frame, this_cache);
  82   trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp,
  83                            lvalp, addrp, realnump, valuep);
  84 }
  85
  86 static CORE_ADDR
  87 tramp_frame_start (CORE_ADDR pc, const struct tramp_frame *tramp)
  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] != 0; ti++)
  93     {
  94       CORE_ADDR func = pc - tramp->insn_size * ti;
  95       int i;
  96       for (i = 0; 1; i++)
  97         {
  98           bfd_byte buf[sizeof (LONGEST)];
  99           CORE_ADDR insn;
 100           if (tramp->insn[i] == 0)
 101             return func;
 102           if (target_read_memory (func + i * tramp->insn_size, buf,
 103                                   tramp->insn_size) != 0)
 104             break;
 105           insn = extract_unsigned_integer (buf, tramp->insn_size);
 106           if (tramp->insn[i] != insn)
 107             break;
 108         }
 109     }
 110   /* Trampoline doesn't match.  */
 111   return 0;
 112 }
 113
 114 static int
 115 tramp_frame_sniffer (const struct frame_unwind *self,
 116                      struct frame_info *next_frame,
 117                      void **this_cache)
 118 {
 119   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 120   CORE_ADDR pc = frame_pc_unwind (next_frame);
 121   CORE_ADDR func;
 122   char *name;
 123   struct tramp_frame_cache *tramp_cache;
 124
 125   /* If the function has a valid symbol name, it isn't a
 126      trampoline.  */
 127   find_pc_partial_function (pc, &name, NULL, NULL);
 128   if (name != NULL)
 129     return 0;
 130   /* If the function lives in a valid section (even without a starting
 131      point) it isn't a trampoline.  */
 132   if (find_pc_section (pc) != NULL)
 133     return 0;
 134   /* Finally, check that the trampoline matches at PC.  */
 135   func = tramp_frame_start (pc, tramp);
 136   if (func == 0)
 137     return 0;
 138   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 139   tramp_cache->func = func;
 140   tramp_cache->tramp_frame = tramp;
 141   (*this_cache) = tramp_cache;
 142   return 1;
 143 }
 144
 145 void
 146 tramp_frame_append (struct gdbarch *gdbarch,
 147                     const struct tramp_frame *tramp_frame)
 148 {
 149   struct frame_data *data;
 150   struct frame_unwind *unwinder;
 151
 152   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 153   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 154
 155   data->tramp_frame = tramp_frame;
 156   unwinder->type = SIGTRAMP_FRAME;
 157   unwinder->unwind_data = data;
 158   unwinder->sniffer = tramp_frame_sniffer;
 159   unwinder->this_id = tramp_frame_this_id;
 160   unwinder->prev_register = tramp_frame_prev_register;
 161   frame_unwind_register_unwinder (gdbarch, unwinder);
 162 }