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 
11 extern void my_direct_func(unsigned long ip);
12 
13 void my_direct_func(unsigned long ip)
14 {
15 	trace_printk("ip %lx\n", ip);
16 }
17 
18 extern void my_tramp(void *);
19 
20 #ifdef CONFIG_X86_64
21 
22 #include <asm/ibt.h>
23 #include <asm/nospec-branch.h>
24 
25 asm (
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 
48 asm (
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 
73 asm (
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>
97 asm (
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 
119 static struct ftrace_ops direct;
120 
121 static 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 
129 static void __exit ftrace_direct_multi_exit(void)
130 {
131 	unregister_ftrace_direct(&direct, (unsigned long) my_tramp, true);
132 }
133 
134 module_init(ftrace_direct_multi_init);
135 module_exit(ftrace_direct_multi_exit);
136 
137 MODULE_AUTHOR("Jiri Olsa");
138 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
139 MODULE_LICENSE("GPL");
140