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_RISCV
21#include <asm/asm.h>
22
23asm (
24"       .pushsection    .text, \"ax\", @progbits\n"
25"       .type           my_tramp, @function\n"
26"       .globl          my_tramp\n"
27"   my_tramp:\n"
28"       addi	sp,sp,-3*"SZREG"\n"
29"       "REG_S"	a0,0*"SZREG"(sp)\n"
30"       "REG_S"	t0,1*"SZREG"(sp)\n"
31"       "REG_S"	ra,2*"SZREG"(sp)\n"
32"       mv	a0,t0\n"
33"       call	my_direct_func\n"
34"       "REG_L"	a0,0*"SZREG"(sp)\n"
35"       "REG_L"	t0,1*"SZREG"(sp)\n"
36"       "REG_L"	ra,2*"SZREG"(sp)\n"
37"       addi	sp,sp,3*"SZREG"\n"
38"       jr	t0\n"
39"       .size           my_tramp, .-my_tramp\n"
40"       .popsection\n"
41);
42
43#endif /* CONFIG_RISCV */
44
45#ifdef CONFIG_X86_64
46
47#include <asm/ibt.h>
48#include <asm/nospec-branch.h>
49
50asm (
51"	.pushsection    .text, \"ax\", @progbits\n"
52"	.type		my_tramp, @function\n"
53"	.globl		my_tramp\n"
54"   my_tramp:"
55	ASM_ENDBR
56"	pushq %rbp\n"
57"	movq %rsp, %rbp\n"
58	CALL_DEPTH_ACCOUNT
59"	pushq %rdi\n"
60"	movq 8(%rbp), %rdi\n"
61"	call my_direct_func\n"
62"	popq %rdi\n"
63"	leave\n"
64	ASM_RET
65"	.size		my_tramp, .-my_tramp\n"
66"	.popsection\n"
67);
68
69#endif /* CONFIG_X86_64 */
70
71#ifdef CONFIG_S390
72
73asm (
74"	.pushsection	.text, \"ax\", @progbits\n"
75"	.type		my_tramp, @function\n"
76"	.globl		my_tramp\n"
77"   my_tramp:"
78"	lgr		%r1,%r15\n"
79"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
80"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
81"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
82"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
83"	lgr		%r2,%r0\n"
84"	brasl		%r14,my_direct_func\n"
85"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
86"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
87"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
88"	lgr		%r1,%r0\n"
89"	br		%r1\n"
90"	.size		my_tramp, .-my_tramp\n"
91"	.popsection\n"
92);
93
94#endif /* CONFIG_S390 */
95
96#ifdef CONFIG_ARM64
97
98asm (
99"	.pushsection	.text, \"ax\", @progbits\n"
100"	.type		my_tramp, @function\n"
101"	.globl		my_tramp\n"
102"   my_tramp:"
103"	hint	34\n" // bti	c
104"	sub	sp, sp, #32\n"
105"	stp	x9, x30, [sp]\n"
106"	str	x0, [sp, #16]\n"
107"	mov	x0, x30\n"
108"	bl	my_direct_func\n"
109"	ldp	x30, x9, [sp]\n"
110"	ldr	x0, [sp, #16]\n"
111"	add	sp, sp, #32\n"
112"	ret	x9\n"
113"	.size		my_tramp, .-my_tramp\n"
114"	.popsection\n"
115);
116
117#endif /* CONFIG_ARM64 */
118
119#ifdef CONFIG_LOONGARCH
120
121#include <asm/asm.h>
122asm (
123"	.pushsection	.text, \"ax\", @progbits\n"
124"	.type		my_tramp, @function\n"
125"	.globl		my_tramp\n"
126"   my_tramp:\n"
127"	addi.d	$sp, $sp, -32\n"
128"	st.d	$a0, $sp, 0\n"
129"	st.d	$t0, $sp, 8\n"
130"	st.d	$ra, $sp, 16\n"
131"	move	$a0, $t0\n"
132"	bl	my_direct_func\n"
133"	ld.d	$a0, $sp, 0\n"
134"	ld.d	$t0, $sp, 8\n"
135"	ld.d	$ra, $sp, 16\n"
136"	addi.d	$sp, $sp, 32\n"
137"	jr	$t0\n"
138"	.size		my_tramp, .-my_tramp\n"
139"	.popsection\n"
140);
141
142#endif /* CONFIG_LOONGARCH */
143
144static struct ftrace_ops direct;
145
146static int __init ftrace_direct_multi_init(void)
147{
148	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
149	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
150
151	return register_ftrace_direct(&direct, (unsigned long) my_tramp);
152}
153
154static void __exit ftrace_direct_multi_exit(void)
155{
156	unregister_ftrace_direct(&direct, (unsigned long) my_tramp, true);
157}
158
159module_init(ftrace_direct_multi_init);
160module_exit(ftrace_direct_multi_exit);
161
162MODULE_AUTHOR("Jiri Olsa");
163MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
164MODULE_LICENSE("GPL");
165