gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004-2021 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           size_t insn_size = tramp->insn_size;
 106
 107           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 108             return func;
 109           if (!safe_frame_unwind_memory (this_frame,
 110                                          func + i * insn_size,
 111                                          {buf, insn_size}))
 112             break;
 113           insn = extract_unsigned_integer (buf, insn_size, byte_order);
 114           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 115             break;
 116         }
 117     }
 118   /* Trampoline doesn't match.  */
 119   return 0;
 120 }
 121
 122 static int
 123 tramp_frame_sniffer (const struct frame_unwind *self,
 124                      struct frame_info *this_frame,
 125                      void **this_cache)
 126 {
 127   const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
 128   CORE_ADDR pc = get_frame_pc (this_frame);
 129   CORE_ADDR func;
 130   struct tramp_frame_cache *tramp_cache;
 131
 132   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 133      section, then this is not a trampoline.  However, this assumption is
 134      false on HPUX which has a signal trampoline that has a name; it can
 135      also be false when using an alternative signal stack.  */
 136   func = tramp_frame_start (tramp, this_frame, pc);
 137   if (func == 0)
 138     return 0;
 139   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 140   tramp_cache->func = func;
 141   tramp_cache->tramp_frame = tramp;
 142   (*this_cache) = tramp_cache;
 143   return 1;
 144 }
 145
 146 void
 147 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 148                               const struct tramp_frame *tramp_frame)
 149 {
 150   struct frame_data *data;
 151   struct frame_unwind *unwinder;
 152   int i;
 153
 154   /* Check that the instruction sequence contains a sentinel.  */
 155   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 156     {
 157       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 158         break;
 159     }
 160   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 161   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 162
 163   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 164   unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
 165
 166   data->tramp_frame = tramp_frame;
 167   unwinder->type = tramp_frame->frame_type;
 168   unwinder->unwind_data = data;
 169   unwinder->sniffer = tramp_frame_sniffer;
 170   unwinder->stop_reason = default_frame_unwind_stop_reason;
 171   unwinder->this_id = tramp_frame_this_id;
 172   unwinder->prev_register = tramp_frame_prev_register;
 173   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 174 }