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
|
/*
* Dynamic function tracing support.
*
* Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
* Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
*
* For licencing details, see COPYING.
*
* Defines low-level handling of mcount calls when the kernel
* is compiled with the -pg flag. When using dynamic ftrace, the
* mcount call-sites get patched with NOP till they are enabled.
* All code mutation routines here are called under stop_machine().
*/
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/stop_machine.h>
#include <asm/cacheflush.h>
#include <asm/opcodes.h>
#include <asm/ftrace.h>
#include <asm/insn.h>
#include <asm/set_memory.h>
#ifdef CONFIG_THUMB2_KERNEL
#define NOP 0xf85deb04 /* pop.w {lr} */
#else
#define NOP 0xe8bd4000 /* pop {lr} */
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
static int __ftrace_modify_code(void *data)
{
int *command = data;
set_kernel_text_rw();
ftrace_modify_all_code(*command);
set_kernel_text_ro();
return 0;
}
void arch_ftrace_update_code(int command)
{
stop_machine(__ftrace_modify_code, &command, NULL);
}
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
{
return NOP;
}
static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
{
return addr;
}
int ftrace_arch_code_modify_prepare(void)
{
set_all_modules_text_rw();
return 0;
}
int ftrace_arch_code_modify_post_process(void)
{
set_all_modules_text_ro();
/* Make sure any TLB misses during machine stop are cleared. */
flush_tlb_all();
return 0;
}
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
return arm_gen_branch_link(pc, addr);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new, bool validate)
{
unsigned long replaced;
if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
old = __opcode_to_mem_thumb32(old);
new = __opcode_to_mem_thumb32(new);
} else {
old = __opcode_to_mem_arm(old);
new = __opcode_to_mem_arm(new);
}
if (validate) {
if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
return -EFAULT;
if (replaced != old)
return -EINVAL;
}
if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long pc;
unsigned long new;
int ret;
pc = (unsigned long)&ftrace_call;
new = ftrace_call_replace(pc, (unsigned long)func);
ret = ftrace_modify_code(pc, 0, new, false);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!ret) {
pc = (unsigned long)&ftrace_regs_call;
new = ftrace_call_replace(pc, (unsigned long)func);
ret = ftrace_modify_code(pc, 0, new, false);
}
#endif
return ret;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long new, old;
unsigned long ip = rec->ip;
old = ftrace_nop_replace(rec);
new = ftrace_call_replace(ip, adjust_address(rec, addr));
return ftrace_modify_code(rec->ip, old, new, true);
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
unsigned long new, old;
unsigned long ip = rec->ip;
old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
new = ftrace_call_replace(ip, adjust_address(rec, addr));
return ftrace_modify_code(rec->ip, old, new, true);
}
#endif
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long ip = rec->ip;
unsigned long old;
unsigned long new;
int ret;
old = ftrace_call_replace(ip, adjust_address(rec, addr));
new = ftrace_nop_replace(rec);
ret = ftrace_modify_code(ip, old, new, true);
return ret;
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long) &return_to_handler;
unsigned long old;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
old = *parent;
*parent = return_hooker;
if (function_graph_enter(old, self_addr, frame_pointer, NULL))
*parent = old;
}
#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_graph_call;
extern unsigned long ftrace_graph_call_old;
extern void ftrace_graph_caller_old(void);
extern unsigned long ftrace_graph_regs_call;
extern void ftrace_graph_regs_caller(void);
static int __ftrace_modify_caller(unsigned long *callsite,
void (*func) (void), bool enable)
{
unsigned long caller_fn = (unsigned long) func;
unsigned long pc = (unsigned long) callsite;
unsigned long branch = arm_gen_branch(pc, caller_fn);
unsigned long nop = 0xe1a00000; /* mov r0, r0 */
unsigned long old = enable ? nop : branch;
unsigned long new = enable ? branch : nop;
return ftrace_modify_code(pc, old, new, true);
}
static int ftrace_modify_graph_caller(bool enable)
{
int ret;
ret = __ftrace_modify_caller(&ftrace_graph_call,
ftrace_graph_caller,
enable);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!ret)
ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
ftrace_graph_regs_caller,
enable);
#endif
return ret;
}
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|
