1
2
3
4#include <linux/sched.h>
5#include <linux/mm.h>
6#include <linux/ptrace.h>
7#include <asm/desc.h>
8
9unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs)
10{
11 unsigned long addr, seg;
12
13 addr = regs->ip;
14 seg = regs->cs & 0xffff;
15 if (v8086_mode(regs)) {
16 addr = (addr & 0xffff) + (seg << 4);
17 return addr;
18 }
19
20
21
22
23
24
25
26 if ((seg & SEGMENT_TI_MASK) == SEGMENT_LDT) {
27 struct desc_struct *desc;
28 unsigned long base;
29
30 seg &= ~7UL;
31
32 mutex_lock(&child->mm->context.lock);
33 if (unlikely((seg >> 3) >= child->mm->context.size))
34 addr = -1L;
35 else {
36 desc = child->mm->context.ldt + seg;
37 base = get_desc_base(desc);
38
39
40 if (!desc->d)
41 addr &= 0xffff;
42 addr += base;
43 }
44 mutex_unlock(&child->mm->context.lock);
45 }
46
47 return addr;
48}
49
50static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
51{
52 int i, copied;
53 unsigned char opcode[15];
54 unsigned long addr = convert_ip_to_linear(child, regs);
55
56 copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
57 for (i = 0; i < copied; i++) {
58 switch (opcode[i]) {
59
60 case 0x9d: case 0xcf:
61 return 1;
62
63
64
65
66 case 0x66: case 0x67:
67 continue;
68
69 case 0x26: case 0x2e:
70 case 0x36: case 0x3e:
71 case 0x64: case 0x65:
72 case 0xf0: case 0xf2: case 0xf3:
73 continue;
74
75#ifdef CONFIG_X86_64
76 case 0x40 ... 0x4f:
77 if (regs->cs != __USER_CS)
78
79 return 0;
80
81 continue;
82#endif
83
84
85
86
87
88
89
90
91
92
93 case 0x9c:
94 default:
95 return 0;
96 }
97 }
98 return 0;
99}
100
101
102
103
104static int enable_single_step(struct task_struct *child)
105{
106 struct pt_regs *regs = task_pt_regs(child);
107 unsigned long oflags;
108
109
110
111
112
113
114
115
116
117
118
119 if (unlikely(test_tsk_thread_flag(child, TIF_SINGLESTEP)))
120 regs->flags |= X86_EFLAGS_TF;
121
122
123
124
125
126
127 set_tsk_thread_flag(child, TIF_SINGLESTEP);
128
129 oflags = regs->flags;
130
131
132 regs->flags |= X86_EFLAGS_TF;
133
134
135
136
137
138
139
140
141
142
143 if (is_setting_trap_flag(child, regs)) {
144 clear_tsk_thread_flag(child, TIF_FORCED_TF);
145 return 0;
146 }
147
148
149
150
151
152 if (oflags & X86_EFLAGS_TF)
153 return test_tsk_thread_flag(child, TIF_FORCED_TF);
154
155 set_tsk_thread_flag(child, TIF_FORCED_TF);
156
157 return 1;
158}
159
160
161
162
163static void write_debugctlmsr(struct task_struct *child, unsigned long val)
164{
165 if (child->thread.debugctlmsr == val)
166 return;
167
168 child->thread.debugctlmsr = val;
169
170 if (child != current)
171 return;
172
173 update_debugctlmsr(val);
174}
175
176
177
178
179static void enable_step(struct task_struct *child, bool block)
180{
181
182
183
184
185
186
187
188 if (enable_single_step(child) && block) {
189 set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
190 write_debugctlmsr(child,
191 child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
192 } else {
193 write_debugctlmsr(child,
194 child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
195
196 if (!child->thread.debugctlmsr)
197 clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
198 }
199}
200
201void user_enable_single_step(struct task_struct *child)
202{
203 enable_step(child, 0);
204}
205
206void user_enable_block_step(struct task_struct *child)
207{
208 enable_step(child, 1);
209}
210
211void user_disable_single_step(struct task_struct *child)
212{
213
214
215
216 write_debugctlmsr(child,
217 child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
218
219 if (!child->thread.debugctlmsr)
220 clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
221
222
223 clear_tsk_thread_flag(child, TIF_SINGLESTEP);
224
225
226 if (test_and_clear_tsk_thread_flag(child, TIF_FORCED_TF))
227 task_pt_regs(child)->flags &= ~X86_EFLAGS_TF;
228}
229