tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 <asm/asm-offsets.h>
7
8extern void my_direct_func(struct vm_area_struct *vma,
9 unsigned long address, unsigned int flags);
10
11void my_direct_func(struct vm_area_struct *vma,
12 unsigned long address, unsigned int flags)
13{
14 trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
15 vma, address, flags);
16}
17
18extern void my_tramp(void *);
19
20#ifdef CONFIG_X86_64
21
22#include <asm/ibt.h>
23
24asm (
25" .pushsection .text, \"ax\", @progbits\n"
26" .type my_tramp, @function\n"
27" .globl my_tramp\n"
28" my_tramp:"
29 ASM_ENDBR
30" pushq %rbp\n"
31" movq %rsp, %rbp\n"
32" pushq %rdi\n"
33" pushq %rsi\n"
34" pushq %rdx\n"
35" call my_direct_func\n"
36" popq %rdx\n"
37" popq %rsi\n"
38" popq %rdi\n"
39" leave\n"
40 ASM_RET
41" .size my_tramp, .-my_tramp\n"
42" .popsection\n"
43);
44
45#endif /* CONFIG_X86_64 */
46
47#ifdef CONFIG_S390
48
49asm (
50" .pushsection .text, \"ax\", @progbits\n"
51" .type my_tramp, @function\n"
52" .globl my_tramp\n"
53" my_tramp:"
54" lgr %r1,%r15\n"
55" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
56" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
57" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
58" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\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
71static int __init ftrace_direct_init(void)
72{
73 return register_ftrace_direct((unsigned long)handle_mm_fault,
74 (unsigned long)my_tramp);
75}
76
77static void __exit ftrace_direct_exit(void)
78{
79 unregister_ftrace_direct((unsigned long)handle_mm_fault,
80 (unsigned long)my_tramp);
81}
82
83module_init(ftrace_direct_init);
84module_exit(ftrace_direct_exit);
85
86MODULE_AUTHOR("Steven Rostedt");
87MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
88MODULE_LICENSE("GPL");