gdb/tramp-frame.c

   1 /* Signal trampoline unwinder, for GDB the GNU Debugger.
   2
   3    Copyright (C) 2004-2024 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 "tramp-frame.h"
  21 #include "extract-store-integer.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 (const frame_info_ptr &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 class frame_unwind_trampoline : public frame_unwind
  61 {
  62 public:
  63   frame_unwind_trampoline (enum frame_type type, const struct frame_data *data,
  64                            frame_prev_arch_ftype *prev_arch_func)
  65     : frame_unwind ("trampoline", type, FRAME_UNWIND_GDB, data),
  66       m_prev_arch (prev_arch_func)
  67   { }
  68
  69   int sniff (const frame_info_ptr &this_frame,
  70              void **this_prologue_cache) const override;
  71
  72   void this_id (const frame_info_ptr &this_frame, void **this_prologue_cache,
  73                 struct frame_id *id) const override;
  74
  75   value *prev_register (const frame_info_ptr &this_frame,
  76                         void **this_prologue_cache,
  77                         int regnum) const override;
  78
  79   struct gdbarch *prev_arch (const frame_info_ptr &this_frame,
  80                              void **this_prologue_cache) const override
  81   {
  82     if (m_prev_arch == nullptr)
  83       return frame_unwind::prev_arch (this_frame, this_prologue_cache);
  84     return m_prev_arch (this_frame, this_prologue_cache);
  85   }
  86
  87 private:
  88   frame_prev_arch_ftype *m_prev_arch;
  89 };
  90
  91 void
  92 frame_unwind_trampoline::this_id (const frame_info_ptr &this_frame,
  93                                   void **this_cache,
  94                                   struct frame_id *this_id) const
  95 {
  96   struct trad_frame_cache *trad_cache
  97     = tramp_frame_cache (this_frame, this_cache);
  98
  99   trad_frame_get_id (trad_cache, this_id);
 100 }
 101
 102 struct value *
 103 frame_unwind_trampoline::prev_register (const frame_info_ptr &this_frame,
 104                                         void **this_cache,
 105                                         int prev_regnum) const
 106 {
 107   struct trad_frame_cache *trad_cache
 108     = tramp_frame_cache (this_frame, this_cache);
 109
 110   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
 111 }
 112
 113 static CORE_ADDR
 114 tramp_frame_start (const struct tramp_frame *tramp,
 115                    const frame_info_ptr &this_frame, CORE_ADDR pc)
 116 {
 117   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 118   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 119   int ti;
 120
 121   /* Check if we can use this trampoline.  */
 122   if (tramp->validate && !tramp->validate (tramp, this_frame, &pc))
 123     return 0;
 124
 125   /* Search through the trampoline for one that matches the
 126      instruction sequence around PC.  */
 127   for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
 128     {
 129       CORE_ADDR func = pc - tramp->insn_size * ti;
 130       int i;
 131
 132       for (i = 0; 1; i++)
 133         {
 134           gdb_byte buf[sizeof (tramp->insn[0])];
 135           ULONGEST insn;
 136           size_t insn_size = tramp->insn_size;
 137
 138           if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
 139             return func;
 140           if (!safe_frame_unwind_memory (this_frame,
 141                                          func + i * insn_size,
 142                                          {buf, insn_size}))
 143             break;
 144           insn = extract_unsigned_integer (buf, insn_size, byte_order);
 145           if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
 146             break;
 147         }
 148     }
 149   /* Trampoline doesn't match.  */
 150   return 0;
 151 }
 152
 153 int
 154 frame_unwind_trampoline::sniff (const frame_info_ptr &this_frame,
 155                                 void **this_cache) const
 156 {
 157   const struct tramp_frame *tramp = unwind_data ()->tramp_frame;
 158   CORE_ADDR pc = get_frame_pc (this_frame);
 159   CORE_ADDR func;
 160   struct tramp_frame_cache *tramp_cache;
 161
 162   /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
 163      section, then this is not a trampoline.  However, this assumption is
 164      false on HPUX which has a signal trampoline that has a name; it can
 165      also be false when using an alternative signal stack.  */
 166   func = tramp_frame_start (tramp, this_frame, pc);
 167   if (func == 0)
 168     return 0;
 169   tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
 170   tramp_cache->func = func;
 171   tramp_cache->tramp_frame = tramp;
 172   (*this_cache) = tramp_cache;
 173   return 1;
 174 }
 175
 176 void
 177 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
 178                               const struct tramp_frame *tramp_frame)
 179 {
 180   struct frame_data *data;
 181   struct frame_unwind *unwinder;
 182   int i;
 183
 184   /* Check that the instruction sequence contains a sentinel.  */
 185   for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
 186     {
 187       if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
 188         break;
 189     }
 190   gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
 191   gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
 192
 193   data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
 194   data->tramp_frame = tramp_frame;
 195
 196   unwinder = obstack_new <frame_unwind_trampoline> (gdbarch_obstack (gdbarch),
 197                                                     tramp_frame->frame_type,
 198                                                     data,
 199                                                     tramp_frame->prev_arch);
 200   frame_unwind_prepend_unwinder (gdbarch, unwinder);
 201 }