1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | #include <linux/module.h> |
3 | |
4 | #include <linux/sched.h> /* for wake_up_process() */ |
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 task_struct *p); |
11 | |
12 | void my_direct_func(struct task_struct *p) |
13 | { |
14 | trace_printk("waking up %s-%d\n" , p->comm, p->pid); |
15 | } |
16 | |
17 | extern void my_tramp(void *); |
18 | |
19 | #ifdef CONFIG_RISCV |
20 | #include <asm/asm.h> |
21 | |
22 | asm ( |
23 | " .pushsection .text, \"ax\", @progbits\n" |
24 | " .type my_tramp, @function\n" |
25 | " .globl my_tramp\n" |
26 | " my_tramp:\n" |
27 | " addi sp,sp,-3*" SZREG"\n" |
28 | " " REG_S" a0,0*" SZREG"(sp)\n" |
29 | " " REG_S" t0,1*" SZREG"(sp)\n" |
30 | " " REG_S" ra,2*" SZREG"(sp)\n" |
31 | " call my_direct_func\n" |
32 | " " REG_L" a0,0*" SZREG"(sp)\n" |
33 | " " REG_L" t0,1*" SZREG"(sp)\n" |
34 | " " REG_L" ra,2*" SZREG"(sp)\n" |
35 | " addi sp,sp,3*" SZREG"\n" |
36 | " jr t0\n" |
37 | " .size my_tramp, .-my_tramp\n" |
38 | " .popsection\n" |
39 | ); |
40 | |
41 | #endif /* CONFIG_RISCV */ |
42 | |
43 | #ifdef CONFIG_X86_64 |
44 | |
45 | #include <asm/ibt.h> |
46 | #include <asm/nospec-branch.h> |
47 | |
48 | asm ( |
49 | " .pushsection .text, \"ax\", @progbits\n" |
50 | " .type my_tramp, @function\n" |
51 | " .globl my_tramp\n" |
52 | " my_tramp:" |
53 | ASM_ENDBR |
54 | " pushq %rbp\n" |
55 | " movq %rsp, %rbp\n" |
56 | CALL_DEPTH_ACCOUNT |
57 | " pushq %rdi\n" |
58 | " call my_direct_func\n" |
59 | " popq %rdi\n" |
60 | " leave\n" |
61 | ASM_RET |
62 | " .size my_tramp, .-my_tramp\n" |
63 | " .popsection\n" |
64 | ); |
65 | |
66 | #endif /* CONFIG_X86_64 */ |
67 | |
68 | #ifdef CONFIG_S390 |
69 | |
70 | asm ( |
71 | " .pushsection .text, \"ax\", @progbits\n" |
72 | " .type my_tramp, @function\n" |
73 | " .globl my_tramp\n" |
74 | " my_tramp:" |
75 | " lgr %r1,%r15\n" |
76 | " stmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
77 | " stg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
78 | " aghi %r15," __stringify(-STACK_FRAME_OVERHEAD)"\n" |
79 | " stg %r1," __stringify(__SF_BACKCHAIN)"(%r15)\n" |
80 | " brasl %r14,my_direct_func\n" |
81 | " aghi %r15," __stringify(STACK_FRAME_OVERHEAD)"\n" |
82 | " lmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
83 | " lg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
84 | " lgr %r1,%r0\n" |
85 | " br %r1\n" |
86 | " .size my_tramp, .-my_tramp\n" |
87 | " .popsection\n" |
88 | ); |
89 | |
90 | #endif /* CONFIG_S390 */ |
91 | |
92 | #ifdef CONFIG_ARM64 |
93 | |
94 | asm ( |
95 | " .pushsection .text, \"ax\", @progbits\n" |
96 | " .type my_tramp, @function\n" |
97 | " .globl my_tramp\n" |
98 | " my_tramp:" |
99 | " hint 34\n" // bti c |
100 | " sub sp, sp, #32\n" |
101 | " stp x9, x30, [sp]\n" |
102 | " str x0, [sp, #16]\n" |
103 | " bl my_direct_func\n" |
104 | " ldp x30, x9, [sp]\n" |
105 | " ldr x0, [sp, #16]\n" |
106 | " add sp, sp, #32\n" |
107 | " ret x9\n" |
108 | " .size my_tramp, .-my_tramp\n" |
109 | " .popsection\n" |
110 | ); |
111 | |
112 | #endif /* CONFIG_ARM64 */ |
113 | |
114 | #ifdef CONFIG_LOONGARCH |
115 | |
116 | asm ( |
117 | " .pushsection .text, \"ax\", @progbits\n" |
118 | " .type my_tramp, @function\n" |
119 | " .globl my_tramp\n" |
120 | " my_tramp:\n" |
121 | " addi.d $sp, $sp, -32\n" |
122 | " st.d $a0, $sp, 0\n" |
123 | " st.d $t0, $sp, 8\n" |
124 | " st.d $ra, $sp, 16\n" |
125 | " bl my_direct_func\n" |
126 | " ld.d $a0, $sp, 0\n" |
127 | " ld.d $t0, $sp, 8\n" |
128 | " ld.d $ra, $sp, 16\n" |
129 | " addi.d $sp, $sp, 32\n" |
130 | " jr $t0\n" |
131 | " .size my_tramp, .-my_tramp\n" |
132 | " .popsection\n" |
133 | ); |
134 | |
135 | #endif /* CONFIG_LOONGARCH */ |
136 | |
137 | static struct ftrace_ops direct; |
138 | |
139 | static int __init ftrace_direct_init(void) |
140 | { |
141 | ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) wake_up_process, remove: 0, reset: 0); |
142 | |
143 | return register_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp); |
144 | } |
145 | |
146 | static void __exit ftrace_direct_exit(void) |
147 | { |
148 | unregister_ftrace_direct(ops: &direct, addr: (unsigned long)my_tramp, free_filters: true); |
149 | } |
150 | |
151 | module_init(ftrace_direct_init); |
152 | module_exit(ftrace_direct_exit); |
153 | |
154 | MODULE_AUTHOR("Steven Rostedt" ); |
155 | MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()" ); |
156 | MODULE_LICENSE("GPL" ); |
157 | |