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