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 #include <asm/ibt.h>
21 #include <asm/nospec-branch.h>
22
23 asm (
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
46 asm (
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
69 static struct ftrace_ops direct;
70
ftrace_direct_multi_init(void)71 static 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
ftrace_direct_multi_exit(void)79 static 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
85 module_init(ftrace_direct_multi_init);
86 module_exit(ftrace_direct_multi_exit);
87
88 MODULE_AUTHOR("Jiri Olsa");
89 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
90 MODULE_LICENSE("GPL");
91