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
|
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2013 Linaro Limited
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
* Copyright (C) 2017 Andes Technology Corporation
*/
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#ifdef CONFIG_DYNAMIC_FTRACE
static int ftrace_check_current_call(unsigned long hook_pos,
unsigned int *expected)
{
unsigned int replaced[2];
unsigned int nops[2] = {NOP4, NOP4};
/* we expect nops at the hook position */
if (!expected)
expected = nops;
/*
* Read the text we want to modify;
* return must be -EFAULT on read error
*/
if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE))
return -EFAULT;
/*
* Make sure it is what we expect it to be;
* return must be -EINVAL on failed comparison
*/
if (memcmp(expected, replaced, sizeof(replaced))) {
pr_err("%p: expected (%08x %08x) but get (%08x %08x)",
(void *)hook_pos, expected[0], expected[1], replaced[0],
replaced[1]);
return -EINVAL;
}
return 0;
}
static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
bool enable)
{
unsigned int call[2];
unsigned int nops[2] = {NOP4, NOP4};
int ret = 0;
make_call(hook_pos, target, call);
/* replace the auipc-jalr pair at once */
ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
MCOUNT_INSN_SIZE);
/* return must be -EPERM on write error */
if (ret)
return -EPERM;
smp_mb();
flush_icache_range((void *)hook_pos, (void *)hook_pos + MCOUNT_INSN_SIZE);
return 0;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
int ret = ftrace_check_current_call(rec->ip, NULL);
if (ret)
return ret;
return __ftrace_modify_call(rec->ip, addr, true);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
unsigned int call[2];
int ret;
make_call(rec->ip, addr, call);
ret = ftrace_check_current_call(rec->ip, call);
if (ret)
return ret;
return __ftrace_modify_call(rec->ip, addr, false);
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
int ret = __ftrace_modify_call((unsigned long)&ftrace_call,
(unsigned long)func, true);
if (!ret) {
ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call,
(unsigned long)func, true);
}
return ret;
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
* Most of this function is copied from arm64.
*/
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;
struct ftrace_graph_ent trace;
int err;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
/*
* We don't suffer access faults, so no extra fault-recovery assembly
* is needed here.
*/
old = *parent;
trace.func = self_addr;
trace.depth = current->curr_ret_stack + 1;
if (!ftrace_graph_entry(&trace))
return;
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer, NULL);
if (err == -EBUSY)
return;
*parent = return_hooker;
}
#endif
|
