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#include <asm/nospec-branch.h>
24
25asm (
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" pushq %rsi\n"
36" pushq %rdx\n"
37" call my_direct_func\n"
38" popq %rdx\n"
39" popq %rsi\n"
40" popq %rdi\n"
41" leave\n"
42 ASM_RET
43" .size my_tramp, .-my_tramp\n"
44" .popsection\n"
45);
46
47#endif /* CONFIG_X86_64 */
48
49#ifdef CONFIG_S390
50
51asm (
52" .pushsection .text, \"ax\", @progbits\n"
53" .type my_tramp, @function\n"
54" .globl my_tramp\n"
55" my_tramp:"
56" lgr %r1,%r15\n"
57" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
58" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
59" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
60" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
61" brasl %r14,my_direct_func\n"
62" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
63" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
64" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
65" lgr %r1,%r0\n"
66" br %r1\n"
67" .size my_tramp, .-my_tramp\n"
68" .popsection\n"
69);
70
71#endif /* CONFIG_S390 */
72
73#ifdef CONFIG_LOONGARCH
74
75asm (
76" .pushsection .text, \"ax\", @progbits\n"
77" .type my_tramp, @function\n"
78" .globl my_tramp\n"
79" my_tramp:\n"
80" addi.d $sp, $sp, -48\n"
81" st.d $a0, $sp, 0\n"
82" st.d $a1, $sp, 8\n"
83" st.d $a2, $sp, 16\n"
84" st.d $t0, $sp, 24\n"
85" st.d $ra, $sp, 32\n"
86" bl my_direct_func\n"
87" ld.d $a0, $sp, 0\n"
88" ld.d $a1, $sp, 8\n"
89" ld.d $a2, $sp, 16\n"
90" ld.d $t0, $sp, 24\n"
91" ld.d $ra, $sp, 32\n"
92" addi.d $sp, $sp, 48\n"
93" jr $t0\n"
94" .size my_tramp, .-my_tramp\n"
95" .popsection\n"
96);
97
98#endif /* CONFIG_LOONGARCH */
99
100static struct ftrace_ops direct;
101
102static int __init ftrace_direct_init(void)
103{
104 ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
105
106 return register_ftrace_direct(&direct, (unsigned long) my_tramp);
107}
108
109static void __exit ftrace_direct_exit(void)
110{
111 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
112}
113
114module_init(ftrace_direct_init);
115module_exit(ftrace_direct_exit);
116
117MODULE_AUTHOR("Steven Rostedt");
118MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
119MODULE_LICENSE("GPL");