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
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
|
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Rui Paulo under sponsorship from the
* FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include "_libproc.h"
#if defined(__aarch64__)
#define AARCH64_BRK 0xd4200000
#define AARCH64_BRK_IMM16_SHIFT 5
#define AARCH64_BRK_IMM16_VAL (0xd << AARCH64_BRK_IMM16_SHIFT)
#define BREAKPOINT_INSTR (AARCH64_BRK | AARCH64_BRK_IMM16_VAL)
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__amd64__) || defined(__i386__)
#define BREAKPOINT_INSTR 0xcc /* int 0x3 */
#define BREAKPOINT_INSTR_SZ 1
#define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ
#elif defined(__arm__)
#define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__powerpc__)
#define BREAKPOINT_INSTR 0x7fe00008 /* trap */
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__riscv)
#define BREAKPOINT_INSTR 0x00100073 /* sbreak */
#define BREAKPOINT_INSTR_SZ 4
#else
#error "Add support for your architecture"
#endif
/*
* Use 4-bytes holder for breakpoint instruction on all the platforms.
* Works for x86 as well until it is endian-little platform.
* (We are coping one byte only on x86 from this 4-bytes piece of
* memory).
*/
typedef uint32_t instr_t;
static int
proc_stop(struct proc_handle *phdl)
{
int status;
if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
DPRINTF("kill %d", proc_getpid(phdl));
return (-1);
} else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
DPRINTF("waitpid %d", proc_getpid(phdl));
return (-1);
} else if (!WIFSTOPPED(status)) {
DPRINTFX("waitpid: unexpected status 0x%x", status);
return (-1);
}
return (0);
}
int
proc_bkptset(struct proc_handle *phdl, uintptr_t address,
unsigned long *saved)
{
struct ptrace_io_desc piod;
int ret = 0, stopped;
instr_t instr;
*saved = 0;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("adding breakpoint at 0x%lx", (unsigned long)address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Read the original instruction.
*/
instr = 0;
piod.piod_op = PIOD_READ_I;
piod.piod_offs = (void *)address;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't read instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
goto done;
}
*saved = instr;
/*
* Write a breakpoint instruction to that address.
*/
instr = BREAKPOINT_INSTR;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)address;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
goto done;
}
done:
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
int
proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
unsigned long saved)
{
struct ptrace_io_desc piod;
int ret = 0, stopped;
instr_t instr;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("removing breakpoint at 0x%lx", (unsigned long)address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Overwrite the breakpoint instruction that we setup previously.
*/
instr = saved;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)address;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
}
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
/*
* Decrement pc so that we delete the breakpoint at the correct
* address, i.e. at the BREAKPOINT_INSTR address.
*
* This is only needed on some architectures where the pc value
* when reading registers points at the instruction after the
* breakpoint, e.g. x86.
*/
void
proc_bkptregadj(unsigned long *pc)
{
(void)pc;
#ifdef BREAKPOINT_ADJUST_SZ
*pc = *pc - BREAKPOINT_ADJUST_SZ;
#endif
}
/*
* Step over the breakpoint.
*/
int
proc_bkptexec(struct proc_handle *phdl, unsigned long saved)
{
unsigned long pc;
unsigned long samesaved;
int status;
if (proc_regget(phdl, REG_PC, &pc) < 0) {
DPRINTFX("ERROR: couldn't get PC register");
return (-1);
}
proc_bkptregadj(&pc);
if (proc_bkptdel(phdl, pc, saved) < 0) {
DPRINTFX("ERROR: couldn't delete breakpoint");
return (-1);
}
/*
* Go back in time and step over the new instruction just
* set up by proc_bkptdel().
*/
proc_regset(phdl, REG_PC, pc);
if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) {
DPRINTFX("ERROR: ptrace step failed");
return (-1);
}
proc_wstatus(phdl);
status = proc_getwstat(phdl);
if (!WIFSTOPPED(status)) {
DPRINTFX("ERROR: don't know why process stopped");
return (-1);
}
/*
* Restore the breakpoint. The saved instruction should be
* the same as the one that we were passed in.
*/
if (proc_bkptset(phdl, pc, &samesaved) < 0) {
DPRINTFX("ERROR: couldn't restore breakpoint");
return (-1);
}
assert(samesaved == saved);
return (0);
}
|
