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
|
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/ftrace.h>
#include <asm/asm-offsets.h>
extern void my_direct_func1(unsigned long ip);
extern void my_direct_func2(unsigned long ip);
void my_direct_func1(unsigned long ip)
{
trace_printk("my direct func1 ip %lx\n", ip);
}
void my_direct_func2(unsigned long ip)
{
trace_printk("my direct func2 ip %lx\n", ip);
}
extern void my_tramp1(void *);
extern void my_tramp2(void *);
#ifdef CONFIG_X86_64
#include <asm/ibt.h>
#include <asm/nospec-branch.h>
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp1, @function\n"
" .globl my_tramp1\n"
" my_tramp1:"
ASM_ENDBR
" pushq %rbp\n"
" movq %rsp, %rbp\n"
CALL_DEPTH_ACCOUNT
" pushq %rdi\n"
" movq 8(%rbp), %rdi\n"
" call my_direct_func1\n"
" popq %rdi\n"
" leave\n"
ASM_RET
" .size my_tramp1, .-my_tramp1\n"
" .type my_tramp2, @function\n"
" .globl my_tramp2\n"
" my_tramp2:"
ASM_ENDBR
" pushq %rbp\n"
" movq %rsp, %rbp\n"
CALL_DEPTH_ACCOUNT
" pushq %rdi\n"
" movq 8(%rbp), %rdi\n"
" call my_direct_func2\n"
" popq %rdi\n"
" leave\n"
ASM_RET
" .size my_tramp2, .-my_tramp2\n"
" .popsection\n"
);
#endif /* CONFIG_X86_64 */
#ifdef CONFIG_S390
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp1, @function\n"
" .globl my_tramp1\n"
" my_tramp1:"
" lgr %r1,%r15\n"
" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
" lgr %r2,%r0\n"
" brasl %r14,my_direct_func1\n"
" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
" lgr %r1,%r0\n"
" br %r1\n"
" .size my_tramp1, .-my_tramp1\n"
"\n"
" .type my_tramp2, @function\n"
" .globl my_tramp2\n"
" my_tramp2:"
" lgr %r1,%r15\n"
" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
" lgr %r2,%r0\n"
" brasl %r14,my_direct_func2\n"
" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
" lgr %r1,%r0\n"
" br %r1\n"
" .size my_tramp2, .-my_tramp2\n"
" .popsection\n"
);
#endif /* CONFIG_S390 */
static unsigned long my_tramp = (unsigned long)my_tramp1;
static unsigned long tramps[2] = {
(unsigned long)my_tramp1,
(unsigned long)my_tramp2,
};
static struct ftrace_ops direct;
static int simple_thread(void *arg)
{
static int t;
int ret = 0;
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(2 * HZ);
if (ret)
continue;
t ^= 1;
ret = modify_ftrace_direct_multi(&direct, tramps[t]);
if (!ret)
my_tramp = tramps[t];
WARN_ON_ONCE(ret);
}
return 0;
}
static struct task_struct *simple_tsk;
static int __init ftrace_direct_multi_init(void)
{
int ret;
ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
ret = register_ftrace_direct_multi(&direct, my_tramp);
if (!ret)
simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
return ret;
}
static void __exit ftrace_direct_multi_exit(void)
{
kthread_stop(simple_tsk);
unregister_ftrace_direct_multi(&direct, my_tramp);
ftrace_free_filter(&direct);
}
module_init(ftrace_direct_multi_init);
module_exit(ftrace_direct_multi_exit);
MODULE_AUTHOR("Jiri Olsa");
MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct_multi()");
MODULE_LICENSE("GPL");
|
