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#ifndef CONFIG_ARM64
  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
137static struct ftrace_ops direct;
138
139static int __init ftrace_direct_init(void)
140{
141	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
142
143	return register_ftrace_direct(&direct, (unsigned long) my_tramp);
144}
145
146static void __exit ftrace_direct_exit(void)
147{
148	unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
 
149}
150
151module_init(ftrace_direct_init);
152module_exit(ftrace_direct_exit);
153
154MODULE_AUTHOR("Steven Rostedt");
155MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()");
156MODULE_LICENSE("GPL");

 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
 7void my_direct_func(struct task_struct *p)
 8{
 9	trace_printk("waking up %s-%d\n", p->comm, p->pid);
10}
11
12extern void my_tramp(void *);
13
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
14asm (
15"	.pushsection    .text, \"ax\", @progbits\n"
16"	.type		my_tramp, @function\n"
17"	.globl		my_tramp\n"
18"   my_tramp:"
 
19"	pushq %rbp\n"
20"	movq %rsp, %rbp\n"
 
21"	pushq %rdi\n"
22"	call my_direct_func\n"
23"	popq %rdi\n"
24"	leave\n"
25"	ret\n"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
26"	.size		my_tramp, .-my_tramp\n"
27"	.popsection\n"
28);
29
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
30
31static int __init ftrace_direct_init(void)
32{
33	return register_ftrace_direct((unsigned long)wake_up_process,
34				     (unsigned long)my_tramp);
 
35}
36
37static void __exit ftrace_direct_exit(void)
38{
39	unregister_ftrace_direct((unsigned long)wake_up_process,
40				 (unsigned long)my_tramp);
41}
42
43module_init(ftrace_direct_init);
44module_exit(ftrace_direct_exit);
45
46MODULE_AUTHOR("Steven Rostedt");
47MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()");
48MODULE_LICENSE("GPL");