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#include <asm/asm-offsets.h>
 8#include <asm/nospec-branch.h>
 9
10extern void my_direct_func(unsigned long ip);
11
12void my_direct_func(unsigned long ip)
13{
14	trace_printk("ip %lx\n", ip);
15}
16
17extern void my_tramp(void *);
18
19#ifdef CONFIG_X86_64
20
21#include <asm/ibt.h>
22
23asm (
24"	.pushsection    .text, \"ax\", @progbits\n"
25"	.type		my_tramp, @function\n"
26"	.globl		my_tramp\n"
27"   my_tramp:"
28	ASM_ENDBR
29"	pushq %rbp\n"
30"	movq %rsp, %rbp\n"
31	CALL_DEPTH_ACCOUNT
32"	pushq %rdi\n"
33"	movq 8(%rbp), %rdi\n"
34"	call my_direct_func\n"
35"	popq %rdi\n"
36"	leave\n"
37	ASM_RET
38"	.size		my_tramp, .-my_tramp\n"
39"	.popsection\n"
40);
41
42#endif /* CONFIG_X86_64 */
43
44#ifdef CONFIG_S390
45
46asm (
47"	.pushsection	.text, \"ax\", @progbits\n"
48"	.type		my_tramp, @function\n"
49"	.globl		my_tramp\n"
50"   my_tramp:"
51"	lgr		%r1,%r15\n"
52"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
53"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
54"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
55"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
56"	lgr		%r2,%r0\n"
57"	brasl		%r14,my_direct_func\n"
58"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
59"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
60"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
61"	lgr		%r1,%r0\n"
62"	br		%r1\n"
63"	.size		my_tramp, .-my_tramp\n"
64"	.popsection\n"
65);
66
67#endif /* CONFIG_S390 */
68
69static struct ftrace_ops direct;
70
71static int __init ftrace_direct_multi_init(void)
72{
73	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
74	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
75
76	return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
77}
78
79static void __exit ftrace_direct_multi_exit(void)
80{
81	unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
82	ftrace_free_filter(&direct);
83}
84
85module_init(ftrace_direct_multi_init);
86module_exit(ftrace_direct_multi_exit);
87
88MODULE_AUTHOR("Jiri Olsa");
89MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
90MODULE_LICENSE("GPL");