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 #ifndef CONFIG_ARM64
7 #include <asm/asm-offsets.h>
8 #endif
9
10 extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
11 unsigned int flags, struct pt_regs *regs);
12
my_direct_func(struct vm_area_struct * vma,unsigned long address,unsigned int flags,struct pt_regs * regs)13 void my_direct_func(struct vm_area_struct *vma, unsigned long address,
14 unsigned int flags, struct pt_regs *regs)
15 {
16 trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
17 vma, address, flags, regs);
18 }
19
20 extern void my_tramp(void *);
21
22 #ifdef CONFIG_X86_64
23
24 #include <asm/ibt.h>
25 #include <asm/nospec-branch.h>
26
27 asm (
28 " .pushsection .text, \"ax\", @progbits\n"
29 " .type my_tramp, @function\n"
30 " .globl my_tramp\n"
31 " my_tramp:"
32 ASM_ENDBR
33 " pushq %rbp\n"
34 " movq %rsp, %rbp\n"
35 CALL_DEPTH_ACCOUNT
36 " pushq %rdi\n"
37 " pushq %rsi\n"
38 " pushq %rdx\n"
39 " pushq %rcx\n"
40 " call my_direct_func\n"
41 " popq %rcx\n"
42 " popq %rdx\n"
43 " popq %rsi\n"
44 " popq %rdi\n"
45 " leave\n"
46 ASM_RET
47 " .size my_tramp, .-my_tramp\n"
48 " .popsection\n"
49 );
50
51 #endif /* CONFIG_X86_64 */
52
53 #ifdef CONFIG_S390
54
55 asm (
56 " .pushsection .text, \"ax\", @progbits\n"
57 " .type my_tramp, @function\n"
58 " .globl my_tramp\n"
59 " my_tramp:"
60 " lgr %r1,%r15\n"
61 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
62 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
63 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
64 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
65 " brasl %r14,my_direct_func\n"
66 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
67 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
68 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
69 " lgr %r1,%r0\n"
70 " br %r1\n"
71 " .size my_tramp, .-my_tramp\n"
72 " .popsection\n"
73 );
74
75 #endif /* CONFIG_S390 */
76
77 #ifdef CONFIG_ARM64
78
79 asm (
80 " .pushsection .text, \"ax\", @progbits\n"
81 " .type my_tramp, @function\n"
82 " .globl my_tramp\n"
83 " my_tramp:"
84 " hint 34\n" // bti c
85 " sub sp, sp, #48\n"
86 " stp x9, x30, [sp]\n"
87 " stp x0, x1, [sp, #16]\n"
88 " stp x2, x3, [sp, #32]\n"
89 " bl my_direct_func\n"
90 " ldp x30, x9, [sp]\n"
91 " ldp x0, x1, [sp, #16]\n"
92 " ldp x2, x3, [sp, #32]\n"
93 " add sp, sp, #48\n"
94 " ret x9\n"
95 " .size my_tramp, .-my_tramp\n"
96 " .popsection\n"
97 );
98
99 #endif /* CONFIG_ARM64 */
100
101 #ifdef CONFIG_LOONGARCH
102
103 asm (
104 " .pushsection .text, \"ax\", @progbits\n"
105 " .type my_tramp, @function\n"
106 " .globl my_tramp\n"
107 " my_tramp:\n"
108 " addi.d $sp, $sp, -48\n"
109 " st.d $a0, $sp, 0\n"
110 " st.d $a1, $sp, 8\n"
111 " st.d $a2, $sp, 16\n"
112 " st.d $t0, $sp, 24\n"
113 " st.d $ra, $sp, 32\n"
114 " bl my_direct_func\n"
115 " ld.d $a0, $sp, 0\n"
116 " ld.d $a1, $sp, 8\n"
117 " ld.d $a2, $sp, 16\n"
118 " ld.d $t0, $sp, 24\n"
119 " ld.d $ra, $sp, 32\n"
120 " addi.d $sp, $sp, 48\n"
121 " jr $t0\n"
122 " .size my_tramp, .-my_tramp\n"
123 " .popsection\n"
124 );
125
126 #endif /* CONFIG_LOONGARCH */
127
128 static struct ftrace_ops direct;
129
ftrace_direct_init(void)130 static int __init ftrace_direct_init(void)
131 {
132 ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
133
134 return register_ftrace_direct(&direct, (unsigned long) my_tramp);
135 }
136
ftrace_direct_exit(void)137 static void __exit ftrace_direct_exit(void)
138 {
139 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
140 }
141
142 module_init(ftrace_direct_init);
143 module_exit(ftrace_direct_exit);
144
145 MODULE_AUTHOR("Steven Rostedt");
146 MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
147 MODULE_LICENSE("GPL");
148
