gdb/displaced-stepping.h

   1 /* Displaced stepping related things.
   2
   3    Copyright (C) 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 #ifndef DISPLACED_STEPPING_H
  21 #define DISPLACED_STEPPING_H
  22
  23 #include "gdbsupport/byte-vector.h"
  24
  25 struct thread_info;
  26
  27 /* True if we are debugging displaced stepping.  */
  28
  29 extern bool debug_displaced;
  30
  31 /* Print a "displaced" debug statement.  */
  32
  33 #define displaced_debug_printf(fmt, ...) \
  34   do \
  35     { \
  36       if (debug_displaced) \
  37         debug_prefixed_printf ("displaced", __func__, fmt, ##__VA_ARGS__); \
  38     } \
  39   while (0)
  40
  41 enum displaced_step_prepare_status
  42 {
  43   /* A displaced stepping buffer was successfully allocated and prepared.  */
  44   DISPLACED_STEP_PREPARE_STATUS_OK,
  45
  46   /* This particular instruction can't be displaced stepped, GDB should fall
  47      back on in-line stepping.  */
  48   DISPLACED_STEP_PREPARE_STATUS_CANT,
  49
  50   /* Not enough resources are available at this time, try again later.  */
  51   DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE,
  52 };
  53
  54 enum displaced_step_finish_status
  55 {
  56   /* Either the instruction was stepped and fixed up, or the specified thread
  57      wasn't executing a displaced step (in which case there's nothing to
  58      finish). */
  59   DISPLACED_STEP_FINISH_STATUS_OK,
  60
  61   /* The thread started a displaced step, but didn't complete it.  */
  62   DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED,
  63 };
  64
  65 /* Base class for displaced stepping closures (the arch-specific data).  */
  66
  67 struct displaced_step_copy_insn_closure
  68 {
  69   virtual ~displaced_step_copy_insn_closure () = 0;
  70 };
  71
  72 using displaced_step_copy_insn_closure_up
  73   = std::unique_ptr<displaced_step_copy_insn_closure>;
  74
  75 /* A simple displaced step closure that contains only a byte buffer.  */
  76
  77 struct buf_displaced_step_copy_insn_closure : displaced_step_copy_insn_closure
  78 {
  79   buf_displaced_step_copy_insn_closure (int buf_size)
  80   : buf (buf_size)
  81   {}
  82
  83   gdb::byte_vector buf;
  84 };
  85
  86 /* Per-inferior displaced stepping state.  */
  87
  88 struct displaced_step_inferior_state
  89 {
  90   displaced_step_inferior_state ()
  91   {
  92     reset ();
  93   }
  94
  95   /* Put this object back in its original state.  */
  96   void reset ()
  97   {
  98     failed_before = 0;
  99     step_thread = nullptr;
 100     step_gdbarch = nullptr;
 101     step_closure.reset ();
 102     step_original = 0;
 103     step_copy = 0;
 104     step_saved_copy.clear ();
 105   }
 106
 107   /* True if preparing a displaced step ever failed.  If so, we won't
 108      try displaced stepping for this inferior again.  */
 109   int failed_before;
 110
 111   /* If this is not nullptr, this is the thread carrying out a
 112      displaced single-step in process PID.  This thread's state will
 113      require fixing up once it has completed its step.  */
 114   thread_info *step_thread;
 115
 116   /* The architecture the thread had when we stepped it.  */
 117   gdbarch *step_gdbarch;
 118
 119   /* The closure provided gdbarch_displaced_step_copy_insn, to be used
 120      for post-step cleanup.  */
 121   displaced_step_copy_insn_closure_up step_closure;
 122
 123   /* The address of the original instruction, and the copy we
 124      made.  */
 125   CORE_ADDR step_original, step_copy;
 126
 127   /* Saved contents of copy area.  */
 128   gdb::byte_vector step_saved_copy;
 129 };
 130
 131 #endif /* DISPLACED_STEPPING_H */