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 <linux/sched/stat.h>
7 #if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32)
8 #include <asm/asm-offsets.h>
9 #endif
10
11 extern void my_direct_func(unsigned long ip);
12
my_direct_func(unsigned long ip)13 void my_direct_func(unsigned long ip)
14 {
15 trace_printk("ip %lx\n", ip);
16 }
17
18 extern void my_tramp(void *);
19
20 #ifdef CONFIG_RISCV
21 #include <asm/asm.h>
22
23 asm (
24 " .pushsection .text, \"ax\", @progbits\n"
25 " .type my_tramp, @function\n"
26 " .globl my_tramp\n"
27 " my_tramp:\n"
28 " addi sp,sp,-3*"SZREG"\n"
29 " "REG_S" a0,0*"SZREG"(sp)\n"
30 " "REG_S" t0,1*"SZREG"(sp)\n"
31 " "REG_S" ra,2*"SZREG"(sp)\n"
32 " mv a0,t0\n"
33 " call my_direct_func\n"
34 " "REG_L" a0,0*"SZREG"(sp)\n"
35 " "REG_L" t0,1*"SZREG"(sp)\n"
36 " "REG_L" ra,2*"SZREG"(sp)\n"
37 " addi sp,sp,3*"SZREG"\n"
38 " jr t0\n"
39 " .size my_tramp, .-my_tramp\n"
40 " .popsection\n"
41 );
42
43 #endif /* CONFIG_RISCV */
44
45 #ifdef CONFIG_X86_64
46
47 #include <asm/ibt.h>
48 #include <asm/nospec-branch.h>
49
50 asm (
51 " .pushsection .text, \"ax\", @progbits\n"
52 " .type my_tramp, @function\n"
53 " .globl my_tramp\n"
54 " my_tramp:"
55 ASM_ENDBR
56 " pushq %rbp\n"
57 " movq %rsp, %rbp\n"
58 CALL_DEPTH_ACCOUNT
59 " pushq %rdi\n"
60 " movq 8(%rbp), %rdi\n"
61 " call my_direct_func\n"
62 " popq %rdi\n"
63 " leave\n"
64 ASM_RET
65 " .size my_tramp, .-my_tramp\n"
66 " .popsection\n"
67 );
68
69 #endif /* CONFIG_X86_64 */
70
71 #ifdef CONFIG_S390
72
73 asm (
74 " .pushsection .text, \"ax\", @progbits\n"
75 " .type my_tramp, @function\n"
76 " .globl my_tramp\n"
77 " my_tramp:"
78 " lgr %r1,%r15\n"
79 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
80 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
81 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
82 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
83 " lgr %r2,%r0\n"
84 " brasl %r14,my_direct_func\n"
85 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
86 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
87 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
88 " lgr %r1,%r0\n"
89 " br %r1\n"
90 " .size my_tramp, .-my_tramp\n"
91 " .popsection\n"
92 );
93
94 #endif /* CONFIG_S390 */
95
96 #ifdef CONFIG_ARM64
97
98 asm (
99 " .pushsection .text, \"ax\", @progbits\n"
100 " .type my_tramp, @function\n"
101 " .globl my_tramp\n"
102 " my_tramp:"
103 " hint 34\n" // bti c
104 " sub sp, sp, #32\n"
105 " stp x9, x30, [sp]\n"
106 " str x0, [sp, #16]\n"
107 " mov x0, x30\n"
108 " bl my_direct_func\n"
109 " ldp x30, x9, [sp]\n"
110 " ldr x0, [sp, #16]\n"
111 " add sp, sp, #32\n"
112 " ret x9\n"
113 " .size my_tramp, .-my_tramp\n"
114 " .popsection\n"
115 );
116
117 #endif /* CONFIG_ARM64 */
118
119 #ifdef CONFIG_LOONGARCH
120
121 #include <asm/asm.h>
122 asm (
123 " .pushsection .text, \"ax\", @progbits\n"
124 " .type my_tramp, @function\n"
125 " .globl my_tramp\n"
126 " my_tramp:\n"
127 " addi.d $sp, $sp, -32\n"
128 " st.d $a0, $sp, 0\n"
129 " st.d $t0, $sp, 8\n"
130 " st.d $ra, $sp, 16\n"
131 " move $a0, $t0\n"
132 " bl my_direct_func\n"
133 " ld.d $a0, $sp, 0\n"
134 " ld.d $t0, $sp, 8\n"
135 " ld.d $ra, $sp, 16\n"
136 " addi.d $sp, $sp, 32\n"
137 " jr $t0\n"
138 " .size my_tramp, .-my_tramp\n"
139 " .popsection\n"
140 );
141
142 #endif /* CONFIG_LOONGARCH */
143
144 #ifdef CONFIG_PPC
145 #include <asm/ppc_asm.h>
146
147 #ifdef CONFIG_PPC64
148 #define STACK_FRAME_SIZE 48
149 #else
150 #define STACK_FRAME_SIZE 24
151 #endif
152
153 #if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL)
154 #define PPC64_TOC_SAVE_AND_UPDATE \
155 " std 2, 24(1)\n" \
156 " bcl 20, 31, 1f\n" \
157 " 1: mflr 12\n" \
158 " ld 2, (99f - 1b)(12)\n"
159 #define PPC64_TOC_RESTORE \
160 " ld 2, 24(1)\n"
161 #define PPC64_TOC \
162 " 99: .quad .TOC.@tocbase\n"
163 #else
164 #define PPC64_TOC_SAVE_AND_UPDATE ""
165 #define PPC64_TOC_RESTORE ""
166 #define PPC64_TOC ""
167 #endif
168
169 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
170 #define PPC_FTRACE_RESTORE_LR \
171 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \
172 " mtlr 0\n"
173 #define PPC_FTRACE_RET \
174 " blr\n"
175 #define PPC_FTRACE_RECOVER_IP \
176 " lwz 8, 4(3)\n" \
177 " li 9, 6\n" \
178 " slw 8, 8, 9\n" \
179 " sraw 8, 8, 9\n" \
180 " add 3, 3, 8\n" \
181 " addi 3, 3, 4\n"
182 #else
183 #define PPC_FTRACE_RESTORE_LR \
184 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \
185 " mtctr 0\n"
186 #define PPC_FTRACE_RET \
187 " mtlr 0\n" \
188 " bctr\n"
189 #define PPC_FTRACE_RECOVER_IP ""
190 #endif
191
192 asm (
193 " .pushsection .text, \"ax\", @progbits\n"
194 " .type my_tramp, @function\n"
195 " .globl my_tramp\n"
196 " my_tramp:\n"
197 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
198 PPC_STLU" 1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
199 " mflr 0\n"
200 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
201 PPC_STLU" 1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
202 PPC64_TOC_SAVE_AND_UPDATE
203 PPC_STL" 3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
204 " mr 3, 0\n"
205 PPC_FTRACE_RECOVER_IP
206 " bl my_direct_func\n"
207 PPC_LL" 3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
208 PPC64_TOC_RESTORE
209 " addi 1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
210 PPC_FTRACE_RESTORE_LR
211 " addi 1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
212 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
213 PPC_FTRACE_RET
214 PPC64_TOC
215 " .size my_tramp, .-my_tramp\n"
216 " .popsection\n"
217 );
218
219 #endif /* CONFIG_PPC */
220
221 static struct ftrace_ops direct;
222
ftrace_direct_multi_init(void)223 static int __init ftrace_direct_multi_init(void)
224 {
225 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
226 ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
227
228 return register_ftrace_direct(&direct, (unsigned long) my_tramp);
229 }
230
ftrace_direct_multi_exit(void)231 static void __exit ftrace_direct_multi_exit(void)
232 {
233 unregister_ftrace_direct(&direct, (unsigned long) my_tramp, true);
234 }
235
236 module_init(ftrace_direct_multi_init);
237 module_exit(ftrace_direct_multi_exit);
238
239 MODULE_AUTHOR("Jiri Olsa");
240 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
241 MODULE_LICENSE("GPL");
242