1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/module.h>
3
4#include <linux/mm.h> /* for handle_mm_fault() */
5#include <linux/ftrace.h>
6#include <linux/sched/stat.h>
7#ifndef CONFIG_ARM64
8#include <asm/asm-offsets.h>
9#endif
10
11extern void my_direct_func(unsigned long ip);
12
13void my_direct_func(unsigned long ip)
14{
15	trace_printk("ip %lx\n", ip);
16}
17
18extern void my_tramp(void *);
19
20#ifdef CONFIG_X86_64
21
22#include <asm/ibt.h>
23#include <asm/nospec-branch.h>
24
25asm (
26"	.pushsection    .text, \"ax\", @progbits\n"
27"	.type		my_tramp, @function\n"
28"	.globl		my_tramp\n"
29"   my_tramp:"
30	ASM_ENDBR
31"	pushq %rbp\n"
32"	movq %rsp, %rbp\n"
33	CALL_DEPTH_ACCOUNT
34"	pushq %rdi\n"
35"	movq 8(%rbp), %rdi\n"
36"	call my_direct_func\n"
37"	popq %rdi\n"
38"	leave\n"
39	ASM_RET
40"	.size		my_tramp, .-my_tramp\n"
41"	.popsection\n"
42);
43
44#endif /* CONFIG_X86_64 */
45
46#ifdef CONFIG_S390
47
48asm (
49"	.pushsection	.text, \"ax\", @progbits\n"
50"	.type		my_tramp, @function\n"
51"	.globl		my_tramp\n"
52"   my_tramp:"
53"	lgr		%r1,%r15\n"
54"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
55"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
56"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
57"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
58"	lgr		%r2,%r0\n"
59"	brasl		%r14,my_direct_func\n"
60"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
61"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
62"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
63"	lgr		%r1,%r0\n"
64"	br		%r1\n"
65"	.size		my_tramp, .-my_tramp\n"
66"	.popsection\n"
67);
68
69#endif /* CONFIG_S390 */
70
71#ifdef CONFIG_ARM64
72
73asm (
74"	.pushsection	.text, \"ax\", @progbits\n"
75"	.type		my_tramp, @function\n"
76"	.globl		my_tramp\n"
77"   my_tramp:"
78"	hint	34\n" // bti	c
79"	sub	sp, sp, #32\n"
80"	stp	x9, x30, [sp]\n"
81"	str	x0, [sp, #16]\n"
82"	mov	x0, x30\n"
83"	bl	my_direct_func\n"
84"	ldp	x30, x9, [sp]\n"
85"	ldr	x0, [sp, #16]\n"
86"	add	sp, sp, #32\n"
87"	ret	x9\n"
88"	.size		my_tramp, .-my_tramp\n"
89"	.popsection\n"
90);
91
92#endif /* CONFIG_ARM64 */
93
94#ifdef CONFIG_LOONGARCH
95
96#include <asm/asm.h>
97asm (
98"	.pushsection	.text, \"ax\", @progbits\n"
99"	.type		my_tramp, @function\n"
100"	.globl		my_tramp\n"
101"   my_tramp:\n"
102"	addi.d	$sp, $sp, -32\n"
103"	st.d	$a0, $sp, 0\n"
104"	st.d	$t0, $sp, 8\n"
105"	st.d	$ra, $sp, 16\n"
106"	move	$a0, $t0\n"
107"	bl	my_direct_func\n"
108"	ld.d	$a0, $sp, 0\n"
109"	ld.d	$t0, $sp, 8\n"
110"	ld.d	$ra, $sp, 16\n"
111"	addi.d	$sp, $sp, 32\n"
112"	jr	$t0\n"
113"	.size		my_tramp, .-my_tramp\n"
114"	.popsection\n"
115);
116
117#endif /* CONFIG_LOONGARCH */
118
119static struct ftrace_ops direct;
120
121static int __init ftrace_direct_multi_init(void)
122{
123	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
124	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
125
126	return register_ftrace_direct(&direct, (unsigned long) my_tramp);
127}
128
129static void __exit ftrace_direct_multi_exit(void)
130{
131	unregister_ftrace_direct(&direct, (unsigned long) my_tramp, true);
132}
133
134module_init(ftrace_direct_multi_init);
135module_exit(ftrace_direct_multi_exit);
136
137MODULE_AUTHOR("Jiri Olsa");
138MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
139MODULE_LICENSE("GPL");
140