gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004-2020 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
  47     = (struct tramp_frame_cache *) *this_cache;
  48
  49   if (tramp_cache->trad_cache == NULL)
  50     {
  51       tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame);
  52       tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
  53                                       this_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 *this_frame,
  62                      void **this_cache,
  63                      struct frame_id *this_id)
  64 {
  65   struct trad_frame_cache *trad_cache
  66     = tramp_frame_cache (this_frame, this_cache);
  67
  68   trad_frame_get_id (trad_cache, this_id);
  69 }
  70
  71 static struct value *
  72 tramp_frame_prev_register (struct frame_info *this_frame,
  73                            void **this_cache,
  74                            int prev_regnum)
  75 {
  76   struct trad_frame_cache *trad_cache
  77     = tramp_frame_cache (this_frame, this_cache);
  78
  79   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
  80 }
  81
  82 static CORE_ADDR
  83 tramp_frame_start (const struct tramp_frame *tramp,
  84                    struct frame_info *this_frame, CORE_ADDR pc)
  85 {
  86   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  87   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  88   int ti;
  89
  90   /* Check if we can use this trampoline.  */
  91   if (tramp->validate && !tramp->validate (tramp, this_frame, &pc))
  92     return 0;
  93
  94   /* Search through the trampoline for one that matches the
  95      instruction sequence around PC.  */
  96   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
  97     {
  98       CORE_ADDR func = pc - tramp->insn_size * ti;
  99       int i;
 100
 101       for (i = 0; 1; i++)
 102         {
 103           gdb_byte buf[sizeof (tramp->insn[0])];
 104           ULONGEST insn;
 105
 106           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 107             return func;
 108           if (!safe_frame_unwind_memory (this_frame,
 109                                          func + i * tramp->insn_size,
 110                                          buf, tramp->insn_size))
 111             break;
 112           insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
 113           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 114             break;
 115         }
 116     }
 117   /* Trampoline doesn't match.  */
 118   return 0;
 119 }
 120
 121 static int
 122 tramp_frame_sniffer (const struct frame_unwind *self,
 123                      struct frame_info *this_frame,
 124                      void **this_cache)
 125 {
 126   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 127   CORE_ADDR pc = get_frame_pc (this_frame);
 128   CORE_ADDR func;
 129   struct tramp_frame_cache *tramp_cache;
 130
 131   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 132      section, then this is not a trampoline.  However, this assumption is
 133      false on HPUX which has a signal trampoline that has a name; it can
 134      also be false when using an alternative signal stack.  */
 135   func = tramp_frame_start (tramp, this_frame, pc);
 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_prepend_unwinder (struct gdbarch *gdbarch,
 147                               const struct tramp_frame *tramp_frame)
 148 {
 149   struct frame_data *data;
 150   struct frame_unwind *unwinder;
 151   int i;
 152
 153   /* Check that the instruction sequence contains a sentinel.  */
 154   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 155     {
 156       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 157         break;
 158     }
 159   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 160   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 161
 162   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 163   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 164
 165   data->tramp_frame = tramp_frame;
 166   unwinder->type = tramp_frame->frame_type;
 167   unwinder->unwind_data = data;
 168   unwinder->sniffer = tramp_frame_sniffer;
 169   unwinder->stop_reason = default_frame_unwind_stop_reason;
 170   unwinder->this_id = tramp_frame_this_id;
 171   unwinder->prev_register = tramp_frame_prev_register;
 172   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 173 }