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#ifndef CONFIG_ARM64
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 $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
144static struct ftrace_ops direct;
145
146static int __init ftrace_direct_multi_init(void)
147{
148 ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) wake_up_process, remove: 0, reset: 0);
149 ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) schedule, remove: 0, reset: 0);
150
151 return register_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp);
152}
153
154static void __exit ftrace_direct_multi_exit(void)
155{
156 unregister_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp, free_filters: true);
157}
158
159module_init(ftrace_direct_multi_init);
160module_exit(ftrace_direct_multi_exit);
161
162MODULE_AUTHOR("Jiri Olsa");
163MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
164MODULE_LICENSE("GPL");
165

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