1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/* Displaced stepping related things.
Copyright (C) 2020-2022 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef DISPLACED_STEPPING_H
#define DISPLACED_STEPPING_H
#include "gdbsupport/array-view.h"
#include "gdbsupport/byte-vector.h"
struct gdbarch;
struct thread_info;
/* True if we are debugging displaced stepping. */
extern bool debug_displaced;
/* Print a "displaced" debug statement. */
#define displaced_debug_printf(fmt, ...) \
debug_prefixed_printf_cond (debug_displaced, "displaced",fmt, ##__VA_ARGS__)
enum displaced_step_prepare_status
{
/* A displaced stepping buffer was successfully allocated and prepared. */
DISPLACED_STEP_PREPARE_STATUS_OK,
/* This particular instruction can't be displaced stepped, GDB should fall
back on in-line stepping. */
DISPLACED_STEP_PREPARE_STATUS_CANT,
/* Not enough resources are available at this time, try again later. */
DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE,
};
enum displaced_step_finish_status
{
/* Either the instruction was stepped and fixed up, or the specified thread
wasn't executing a displaced step (in which case there's nothing to
finish). */
DISPLACED_STEP_FINISH_STATUS_OK,
/* The thread started a displaced step, but didn't complete it. */
DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED,
};
/* Data returned by a gdbarch displaced_step_copy_insn method, to be passed to
the matching displaced_step_fixup method. */
struct displaced_step_copy_insn_closure
{
virtual ~displaced_step_copy_insn_closure () = 0;
};
using displaced_step_copy_insn_closure_up
= std::unique_ptr<displaced_step_copy_insn_closure>;
/* A simple displaced step closure that contains only a byte buffer. */
struct buf_displaced_step_copy_insn_closure : displaced_step_copy_insn_closure
{
buf_displaced_step_copy_insn_closure (int buf_size)
: buf (buf_size)
{}
/* The content of this buffer is up to the user of the class, but typically
original instruction bytes, used during fixup to determine what needs to
be fixed up. */
gdb::byte_vector buf;
};
/* Per-inferior displaced stepping state. */
struct displaced_step_inferior_state
{
displaced_step_inferior_state ()
{
reset ();
}
/* Put this object back in its original state. */
void reset ()
{
failed_before = false;
in_progress_count = 0;
unavailable = false;
}
/* True if preparing a displaced step ever failed. If so, we won't
try displaced stepping for this inferior again. */
bool failed_before;
/* Number of displaced steps in progress for this inferior. */
unsigned int in_progress_count;
/* If true, this tells GDB that it's not worth asking the gdbarch displaced
stepping implementation to prepare a displaced step, because it would
return UNAVAILABLE. This is set and reset by the gdbarch in the
displaced_step_prepare and displaced_step_finish methods. */
bool unavailable;
};
/* Per-thread displaced stepping state. */
struct displaced_step_thread_state
{
/* Return true if this thread is currently executing a displaced step. */
bool in_progress () const
{
return m_original_gdbarch != nullptr;
}
/* Return the gdbarch of the thread prior to the step. */
gdbarch *get_original_gdbarch () const
{
return m_original_gdbarch;
}
/* Mark this thread as currently executing a displaced step.
ORIGINAL_GDBARCH is the current gdbarch of the thread (before the step
is executed). */
void set (gdbarch *original_gdbarch)
{
m_original_gdbarch = original_gdbarch;
}
/* Mark this thread as no longer executing a displaced step. */
void reset ()
{
m_original_gdbarch = nullptr;
}
private:
gdbarch *m_original_gdbarch = nullptr;
};
/* Control access to multiple displaced stepping buffers at fixed addresses. */
struct displaced_step_buffers
{
explicit displaced_step_buffers (gdb::array_view<CORE_ADDR> buffer_addrs)
{
gdb_assert (buffer_addrs.size () > 0);
m_buffers.reserve (buffer_addrs.size ());
for (CORE_ADDR buffer_addr : buffer_addrs)
m_buffers.emplace_back (buffer_addr);
}
displaced_step_prepare_status prepare (thread_info *thread,
CORE_ADDR &displaced_pc);
displaced_step_finish_status finish (gdbarch *arch, thread_info *thread,
gdb_signal sig);
const displaced_step_copy_insn_closure *
copy_insn_closure_by_addr (CORE_ADDR addr);
void restore_in_ptid (ptid_t ptid);
private:
/* State of a single buffer. */
struct displaced_step_buffer
{
explicit displaced_step_buffer (CORE_ADDR addr)
: addr (addr)
{}
/* Address of the buffer. */
const CORE_ADDR addr;
/* The original PC of the instruction currently being stepped. */
CORE_ADDR original_pc = 0;
/* If set, the thread currently using the buffer. If unset, the buffer is not
used. */
thread_info *current_thread = nullptr;
/* Saved copy of the bytes in the displaced buffer, to be restored once the
buffer is no longer used. */
gdb::byte_vector saved_copy;
/* Closure obtained from gdbarch_displaced_step_copy_insn, to be passed to
gdbarch_displaced_step_fixup_insn. */
displaced_step_copy_insn_closure_up copy_insn_closure;
};
std::vector<displaced_step_buffer> m_buffers;
};
#endif /* DISPLACED_STEPPING_H */
|
