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
11extern void my_direct_func(unsigned long ip);
12
13void my_direct_func(unsigned long ip)
14{
15 trace_printk("ip %lx\n", ip);
16}
17
18extern void my_tramp(void *);
19
20#ifdef CONFIG_RISCV
21#include <asm/asm.h>
22
23asm (
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
50asm (
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
73asm (
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
98asm (
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>
122asm (
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 $ra, $sp, 8\n"
135" ld.d $t0, $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
192asm (
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
221static struct ftrace_ops direct;
222
223static int __init ftrace_direct_multi_init(void)
224{
225 ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) wake_up_process, remove: 0, reset: 0);
226 ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) schedule, remove: 0, reset: 0);
227
228 return register_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp);
229}
230
231static void __exit ftrace_direct_multi_exit(void)
232{
233 unregister_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp, free_filters: true);
234}
235
236module_init(ftrace_direct_multi_init);
237module_exit(ftrace_direct_multi_exit);
238
239MODULE_AUTHOR("Jiri Olsa");
240MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
241MODULE_LICENSE("GPL");
242

source code of linux/samples/ftrace/ftrace-direct-multi.c