1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | #include <linux/module.h> |
3 | #include <linux/kthread.h> |
4 | #include <linux/ftrace.h> |
5 | #ifndef CONFIG_ARM64 |
6 | #include <asm/asm-offsets.h> |
7 | #endif |
8 | |
9 | extern void my_direct_func1(void); |
10 | extern void my_direct_func2(void); |
11 | |
12 | void my_direct_func1(void) |
13 | { |
14 | trace_printk("my direct func1\n" ); |
15 | } |
16 | |
17 | void my_direct_func2(void) |
18 | { |
19 | trace_printk("my direct func2\n" ); |
20 | } |
21 | |
22 | extern void my_tramp1(void *); |
23 | extern void my_tramp2(void *); |
24 | |
25 | static unsigned long my_ip = (unsigned long)schedule; |
26 | |
27 | #ifdef CONFIG_RISCV |
28 | #include <asm/asm.h> |
29 | |
30 | asm ( |
31 | " .pushsection .text, \"ax\", @progbits\n" |
32 | " .type my_tramp1, @function\n" |
33 | " .globl my_tramp1\n" |
34 | " my_tramp1:\n" |
35 | " addi sp,sp,-2*" SZREG"\n" |
36 | " " REG_S" t0,0*" SZREG"(sp)\n" |
37 | " " REG_S" ra,1*" SZREG"(sp)\n" |
38 | " call my_direct_func1\n" |
39 | " " REG_L" t0,0*" SZREG"(sp)\n" |
40 | " " REG_L" ra,1*" SZREG"(sp)\n" |
41 | " addi sp,sp,2*" SZREG"\n" |
42 | " jr t0\n" |
43 | " .size my_tramp1, .-my_tramp1\n" |
44 | " .type my_tramp2, @function\n" |
45 | " .globl my_tramp2\n" |
46 | |
47 | " my_tramp2:\n" |
48 | " addi sp,sp,-2*" SZREG"\n" |
49 | " " REG_S" t0,0*" SZREG"(sp)\n" |
50 | " " REG_S" ra,1*" SZREG"(sp)\n" |
51 | " call my_direct_func2\n" |
52 | " " REG_L" t0,0*" SZREG"(sp)\n" |
53 | " " REG_L" ra,1*" SZREG"(sp)\n" |
54 | " addi sp,sp,2*" SZREG"\n" |
55 | " jr t0\n" |
56 | " .size my_tramp2, .-my_tramp2\n" |
57 | " .popsection\n" |
58 | ); |
59 | |
60 | #endif /* CONFIG_RISCV */ |
61 | |
62 | #ifdef CONFIG_X86_64 |
63 | |
64 | #include <asm/ibt.h> |
65 | #include <asm/nospec-branch.h> |
66 | |
67 | asm ( |
68 | " .pushsection .text, \"ax\", @progbits\n" |
69 | " .type my_tramp1, @function\n" |
70 | " .globl my_tramp1\n" |
71 | " my_tramp1:" |
72 | ASM_ENDBR |
73 | " pushq %rbp\n" |
74 | " movq %rsp, %rbp\n" |
75 | CALL_DEPTH_ACCOUNT |
76 | " call my_direct_func1\n" |
77 | " leave\n" |
78 | " .size my_tramp1, .-my_tramp1\n" |
79 | ASM_RET |
80 | |
81 | " .type my_tramp2, @function\n" |
82 | " .globl my_tramp2\n" |
83 | " my_tramp2:" |
84 | ASM_ENDBR |
85 | " pushq %rbp\n" |
86 | " movq %rsp, %rbp\n" |
87 | CALL_DEPTH_ACCOUNT |
88 | " call my_direct_func2\n" |
89 | " leave\n" |
90 | ASM_RET |
91 | " .size my_tramp2, .-my_tramp2\n" |
92 | " .popsection\n" |
93 | ); |
94 | |
95 | #endif /* CONFIG_X86_64 */ |
96 | |
97 | #ifdef CONFIG_S390 |
98 | |
99 | asm ( |
100 | " .pushsection .text, \"ax\", @progbits\n" |
101 | " .type my_tramp1, @function\n" |
102 | " .globl my_tramp1\n" |
103 | " my_tramp1:" |
104 | " lgr %r1,%r15\n" |
105 | " stmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
106 | " stg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
107 | " aghi %r15," __stringify(-STACK_FRAME_OVERHEAD)"\n" |
108 | " stg %r1," __stringify(__SF_BACKCHAIN)"(%r15)\n" |
109 | " brasl %r14,my_direct_func1\n" |
110 | " aghi %r15," __stringify(STACK_FRAME_OVERHEAD)"\n" |
111 | " lmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
112 | " lg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
113 | " lgr %r1,%r0\n" |
114 | " br %r1\n" |
115 | " .size my_tramp1, .-my_tramp1\n" |
116 | " .type my_tramp2, @function\n" |
117 | " .globl my_tramp2\n" |
118 | " my_tramp2:" |
119 | " lgr %r1,%r15\n" |
120 | " stmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
121 | " stg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
122 | " aghi %r15," __stringify(-STACK_FRAME_OVERHEAD)"\n" |
123 | " stg %r1," __stringify(__SF_BACKCHAIN)"(%r15)\n" |
124 | " brasl %r14,my_direct_func2\n" |
125 | " aghi %r15," __stringify(STACK_FRAME_OVERHEAD)"\n" |
126 | " lmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
127 | " lg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
128 | " lgr %r1,%r0\n" |
129 | " br %r1\n" |
130 | " .size my_tramp2, .-my_tramp2\n" |
131 | " .popsection\n" |
132 | ); |
133 | |
134 | #endif /* CONFIG_S390 */ |
135 | |
136 | #ifdef CONFIG_ARM64 |
137 | |
138 | asm ( |
139 | " .pushsection .text, \"ax\", @progbits\n" |
140 | " .type my_tramp1, @function\n" |
141 | " .globl my_tramp1\n" |
142 | " my_tramp1:" |
143 | " hint 34\n" // bti c |
144 | " sub sp, sp, #16\n" |
145 | " stp x9, x30, [sp]\n" |
146 | " bl my_direct_func1\n" |
147 | " ldp x30, x9, [sp]\n" |
148 | " add sp, sp, #16\n" |
149 | " ret x9\n" |
150 | " .size my_tramp1, .-my_tramp1\n" |
151 | |
152 | " .type my_tramp2, @function\n" |
153 | " .globl my_tramp2\n" |
154 | " my_tramp2:" |
155 | " hint 34\n" // bti c |
156 | " sub sp, sp, #16\n" |
157 | " stp x9, x30, [sp]\n" |
158 | " bl my_direct_func2\n" |
159 | " ldp x30, x9, [sp]\n" |
160 | " add sp, sp, #16\n" |
161 | " ret x9\n" |
162 | " .size my_tramp2, .-my_tramp2\n" |
163 | " .popsection\n" |
164 | ); |
165 | |
166 | #endif /* CONFIG_ARM64 */ |
167 | |
168 | #ifdef CONFIG_LOONGARCH |
169 | |
170 | asm ( |
171 | " .pushsection .text, \"ax\", @progbits\n" |
172 | " .type my_tramp1, @function\n" |
173 | " .globl my_tramp1\n" |
174 | " my_tramp1:\n" |
175 | " addi.d $sp, $sp, -16\n" |
176 | " st.d $t0, $sp, 0\n" |
177 | " st.d $ra, $sp, 8\n" |
178 | " bl my_direct_func1\n" |
179 | " ld.d $t0, $sp, 0\n" |
180 | " ld.d $ra, $sp, 8\n" |
181 | " addi.d $sp, $sp, 16\n" |
182 | " jr $t0\n" |
183 | " .size my_tramp1, .-my_tramp1\n" |
184 | |
185 | " .type my_tramp2, @function\n" |
186 | " .globl my_tramp2\n" |
187 | " my_tramp2:\n" |
188 | " addi.d $sp, $sp, -16\n" |
189 | " st.d $t0, $sp, 0\n" |
190 | " st.d $ra, $sp, 8\n" |
191 | " bl my_direct_func2\n" |
192 | " ld.d $t0, $sp, 0\n" |
193 | " ld.d $ra, $sp, 8\n" |
194 | " addi.d $sp, $sp, 16\n" |
195 | " jr $t0\n" |
196 | " .size my_tramp2, .-my_tramp2\n" |
197 | " .popsection\n" |
198 | ); |
199 | |
200 | #endif /* CONFIG_LOONGARCH */ |
201 | |
202 | static struct ftrace_ops direct; |
203 | |
204 | static unsigned long my_tramp = (unsigned long)my_tramp1; |
205 | static unsigned long tramps[2] = { |
206 | (unsigned long)my_tramp1, |
207 | (unsigned long)my_tramp2, |
208 | }; |
209 | |
210 | static int simple_thread(void *arg) |
211 | { |
212 | static int t; |
213 | int ret = 0; |
214 | |
215 | while (!kthread_should_stop()) { |
216 | set_current_state(TASK_INTERRUPTIBLE); |
217 | schedule_timeout(timeout: 2 * HZ); |
218 | |
219 | if (ret) |
220 | continue; |
221 | t ^= 1; |
222 | ret = modify_ftrace_direct(ops: &direct, addr: tramps[t]); |
223 | if (!ret) |
224 | my_tramp = tramps[t]; |
225 | WARN_ON_ONCE(ret); |
226 | } |
227 | |
228 | return 0; |
229 | } |
230 | |
231 | static struct task_struct *simple_tsk; |
232 | |
233 | static int __init ftrace_direct_init(void) |
234 | { |
235 | int ret; |
236 | |
237 | ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) my_ip, remove: 0, reset: 0); |
238 | ret = register_ftrace_direct(ops: &direct, addr: my_tramp); |
239 | |
240 | if (!ret) |
241 | simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn" ); |
242 | return ret; |
243 | } |
244 | |
245 | static void __exit ftrace_direct_exit(void) |
246 | { |
247 | kthread_stop(k: simple_tsk); |
248 | unregister_ftrace_direct(ops: &direct, addr: my_tramp, free_filters: true); |
249 | } |
250 | |
251 | module_init(ftrace_direct_init); |
252 | module_exit(ftrace_direct_exit); |
253 | |
254 | MODULE_AUTHOR("Steven Rostedt" ); |
255 | MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()" ); |
256 | MODULE_LICENSE("GPL" ); |
257 | |