Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32)
7#include <asm/asm-offsets.h>
8#endif
9
10extern void my_direct_func(struct task_struct *p);
11
12void my_direct_func(struct task_struct *p)
13{
14 trace_printk("waking up %s-%d\n", p->comm, p->pid);
15}
16
17extern void my_tramp(void *);
18
19#ifdef CONFIG_RISCV
20#include <asm/asm.h>
21
22asm (
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
48asm (
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
70asm (
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
94asm (
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
116asm (
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#ifdef CONFIG_PPC
138#include <asm/ppc_asm.h>
139
140#ifdef CONFIG_PPC64
141#define STACK_FRAME_SIZE 48
142#else
143#define STACK_FRAME_SIZE 24
144#endif
145
146#if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL)
147#define PPC64_TOC_SAVE_AND_UPDATE \
148" std 2, 24(1)\n" \
149" bcl 20, 31, 1f\n" \
150" 1: mflr 12\n" \
151" ld 2, (99f - 1b)(12)\n"
152#define PPC64_TOC_RESTORE \
153" ld 2, 24(1)\n"
154#define PPC64_TOC \
155" 99: .quad .TOC.@tocbase\n"
156#else
157#define PPC64_TOC_SAVE_AND_UPDATE ""
158#define PPC64_TOC_RESTORE ""
159#define PPC64_TOC ""
160#endif
161
162#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
163#define PPC_FTRACE_RESTORE_LR \
164 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \
165" mtlr 0\n"
166#define PPC_FTRACE_RET \
167" blr\n"
168#else
169#define PPC_FTRACE_RESTORE_LR \
170 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \
171" mtctr 0\n"
172#define PPC_FTRACE_RET \
173" mtlr 0\n" \
174" bctr\n"
175#endif
176
177asm (
178" .pushsection .text, \"ax\", @progbits\n"
179" .type my_tramp, @function\n"
180" .globl my_tramp\n"
181" my_tramp:\n"
182 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
183 PPC_STLU" 1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
184" mflr 0\n"
185 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
186 PPC_STLU" 1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
187 PPC64_TOC_SAVE_AND_UPDATE
188 PPC_STL" 3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
189" bl my_direct_func\n"
190 PPC_LL" 3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
191 PPC64_TOC_RESTORE
192" addi 1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
193 PPC_FTRACE_RESTORE_LR
194" addi 1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
195 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n"
196 PPC_FTRACE_RET
197 PPC64_TOC
198" .size my_tramp, .-my_tramp\n"
199" .popsection\n"
200);
201
202#endif /* CONFIG_PPC */
203
204static struct ftrace_ops direct;
205
206static int __init ftrace_direct_init(void)
207{
208 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
209
210 return register_ftrace_direct(&direct, (unsigned long) my_tramp);
211}
212
213static void __exit ftrace_direct_exit(void)
214{
215 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
216}
217
218module_init(ftrace_direct_init);
219module_exit(ftrace_direct_exit);
220
221MODULE_AUTHOR("Steven Rostedt");
222MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()");
223MODULE_LICENSE("GPL");