summaryrefslogtreecommitdiff
path: root/samples/ftrace/ftrace-direct-too.c
blob: 05c3585ac15ea34a926c30367298cc64aaf045e8 (plain)
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
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>

#include <linux/mm.h> /* for handle_mm_fault() */
#include <linux/ftrace.h>
#include <asm/asm-offsets.h>

extern void my_direct_func(struct vm_area_struct *vma,
			   unsigned long address, unsigned int flags);

void my_direct_func(struct vm_area_struct *vma,
			unsigned long address, unsigned int flags)
{
	trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
		     vma, address, flags);
}

extern void my_tramp(void *);

#ifdef CONFIG_X86_64

#include <asm/ibt.h>
#include <asm/nospec-branch.h>

asm (
"	.pushsection    .text, \"ax\", @progbits\n"
"	.type		my_tramp, @function\n"
"	.globl		my_tramp\n"
"   my_tramp:"
	ASM_ENDBR
"	pushq %rbp\n"
"	movq %rsp, %rbp\n"
	CALL_DEPTH_ACCOUNT
"	pushq %rdi\n"
"	pushq %rsi\n"
"	pushq %rdx\n"
"	call my_direct_func\n"
"	popq %rdx\n"
"	popq %rsi\n"
"	popq %rdi\n"
"	leave\n"
	ASM_RET
"	.size		my_tramp, .-my_tramp\n"
"	.popsection\n"
);

#endif /* CONFIG_X86_64 */

#ifdef CONFIG_S390

asm (
"	.pushsection	.text, \"ax\", @progbits\n"
"	.type		my_tramp, @function\n"
"	.globl		my_tramp\n"
"   my_tramp:"
"	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"
"	brasl		%r14,my_direct_func\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_tramp, .-my_tramp\n"
"	.popsection\n"
);

#endif /* CONFIG_S390 */

static struct ftrace_ops direct;

static int __init ftrace_direct_init(void)
{
	ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);

	return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
}

static void __exit ftrace_direct_exit(void)
{
	unregister_ftrace_direct_multi(&direct, (unsigned long)my_tramp, true);
}

module_init(ftrace_direct_init);
module_exit(ftrace_direct_exit);

MODULE_AUTHOR("Steven Rostedt");
MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct_multi()");
MODULE_LICENSE("GPL");