[linux-2.6-block.git] / samples / ftrace / ftrace-direct-modify.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/ftrace.h>
#include <asm/asm-offsets.h>

extern void my_direct_func1(void);
extern void my_direct_func2(void);

void my_direct_func1(void)
{
	trace_printk("my direct func1\n");
}

void my_direct_func2(void)
{
	trace_printk("my direct func2\n");
}

extern void my_tramp1(void *);
extern void my_tramp2(void *);

static unsigned long my_ip = (unsigned long)schedule;

#ifdef CONFIG_X86_64

#include <asm/ibt.h>
#include <asm/nospec-branch.h>

asm (
"	.pushsection    .text, \"ax\", @progbits\n"
"	.type		my_tramp1, @function\n"
"	.globl		my_tramp1\n"
"   my_tramp1:"
	ASM_ENDBR
"	pushq %rbp\n"
"	movq %rsp, %rbp\n"
	CALL_DEPTH_ACCOUNT
"	call my_direct_func1\n"
"	leave\n"
"	.size		my_tramp1, .-my_tramp1\n"
	ASM_RET

"	.type		my_tramp2, @function\n"
"	.globl		my_tramp2\n"
"   my_tramp2:"
	ASM_ENDBR
"	pushq %rbp\n"
"	movq %rsp, %rbp\n"
	CALL_DEPTH_ACCOUNT
"	call my_direct_func2\n"
"	leave\n"
	ASM_RET
"	.size		my_tramp2, .-my_tramp2\n"
"	.popsection\n"
);

#endif /* CONFIG_X86_64 */

#ifdef CONFIG_S390

asm (
"	.pushsection	.text, \"ax\", @progbits\n"
"	.type		my_tramp1, @function\n"
"	.globl		my_tramp1\n"
"   my_tramp1:"
"	lgr		%r1,%r15\n"
"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
"	brasl		%r14,my_direct_func1\n"
"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
"	lgr		%r1,%r0\n"
"	br		%r1\n"
"	.size		my_tramp1, .-my_tramp1\n"
"	.type		my_tramp2, @function\n"
"	.globl		my_tramp2\n"
"   my_tramp2:"
"	lgr		%r1,%r15\n"
"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
"	brasl		%r14,my_direct_func2\n"
"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
"	lgr		%r1,%r0\n"
"	br		%r1\n"
"	.size		my_tramp2, .-my_tramp2\n"
"	.popsection\n"
);

#endif /* CONFIG_S390 */

#ifdef CONFIG_LOONGARCH

asm (
"	.pushsection    .text, \"ax\", @progbits\n"
"	.type		my_tramp1, @function\n"
"	.globl		my_tramp1\n"
"   my_tramp1:\n"
"	addi.d	$sp, $sp, -16\n"
"	st.d	$t0, $sp, 0\n"
"	st.d	$ra, $sp, 8\n"
"	bl	my_direct_func1\n"
"	ld.d	$t0, $sp, 0\n"
"	ld.d	$ra, $sp, 8\n"
"	addi.d	$sp, $sp, 16\n"
"	jr	$t0\n"
"	.size		my_tramp1, .-my_tramp1\n"

"	.type		my_tramp2, @function\n"
"	.globl		my_tramp2\n"
"   my_tramp2:\n"
"	addi.d	$sp, $sp, -16\n"
"	st.d	$t0, $sp, 0\n"
"	st.d	$ra, $sp, 8\n"
"	bl	my_direct_func2\n"
"	ld.d	$t0, $sp, 0\n"
"	ld.d	$ra, $sp, 8\n"
"	addi.d	$sp, $sp, 16\n"
"	jr	$t0\n"
"	.size		my_tramp2, .-my_tramp2\n"
"	.popsection\n"
);

#endif /* CONFIG_LOONGARCH */

static struct ftrace_ops direct;

static unsigned long my_tramp = (unsigned long)my_tramp1;
static unsigned long tramps[2] = {
	(unsigned long)my_tramp1,
	(unsigned long)my_tramp2,
};

static int simple_thread(void *arg)
{
	static int t;
	int ret = 0;

	while (!kthread_should_stop()) {
		set_current_state(TASK_INTERRUPTIBLE);
		schedule_timeout(2 * HZ);

		if (ret)
			continue;
		t ^= 1;
		ret = modify_ftrace_direct(&direct, tramps[t]);
		if (!ret)
			my_tramp = tramps[t];
		WARN_ON_ONCE(ret);
	}

	return 0;
}

static struct task_struct *simple_tsk;

static int __init ftrace_direct_init(void)
{
	int ret;

	ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0);
	ret = register_ftrace_direct(&direct, my_tramp);

	if (!ret)
		simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
	return ret;
}

static void __exit ftrace_direct_exit(void)
{
	kthread_stop(simple_tsk);
	unregister_ftrace_direct(&direct, my_tramp, true);
}

module_init(ftrace_direct_init);
module_exit(ftrace_direct_exit);

MODULE_AUTHOR("Steven Rostedt");
MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
MODULE_LICENSE("GPL");
Commit	Line	Data
ae0cc3b7 SRV	1	// SPDX-License-Identifier: GPL-2.0-only
	2	#include <linux/module.h>
	3	#include <linux/kthread.h>
	4	#include <linux/ftrace.h>
1254cfbc	5	#include <asm/asm-offsets.h>
ae0cc3b7	6
0daf5cb2 JO	7	extern void my_direct_func1(void);
	8	extern void my_direct_func2(void);
	9
ae0cc3b7 SRV	10	void my_direct_func1(void)
	11	{
	12	trace_printk("my direct func1\n");
	13	}
	14
	15	void my_direct_func2(void)
	16	{
	17	trace_printk("my direct func2\n");
	18	}
	19
	20	extern void my_tramp1(void *);
	21	extern void my_tramp2(void *);
	22
	23	static unsigned long my_ip = (unsigned long)schedule;
	24
1254cfbc HC	25	#ifdef CONFIG_X86_64
1254cfbc HC	26
0aec21cf	27	#include <asm/ibt.h>
01678fbc	28	#include <asm/nospec-branch.h>
0aec21cf	29
ae0cc3b7 SRV	30	asm (
ae0cc3b7 SRV	31	" .pushsection .text, \"ax\", @progbits\n"
9d907f1a	32	" .type my_tramp1, @function\n"
983df5f2	33	" .globl my_tramp1\n"
ae0cc3b7	34	" my_tramp1:"
0aec21cf	35	ASM_ENDBR
ae0cc3b7 SRV	36	" pushq %rbp\n"
ae0cc3b7 SRV	37	" movq %rsp, %rbp\n"
ee3e2469	38	CALL_DEPTH_ACCOUNT
ae0cc3b7 SRV	39	" call my_direct_func1\n"
ae0cc3b7 SRV	40	" leave\n"
9d907f1a	41	" .size my_tramp1, .-my_tramp1\n"
b17c2baa	42	ASM_RET
0aec21cf	43
9d907f1a	44	" .type my_tramp2, @function\n"
983df5f2	45	" .globl my_tramp2\n"
ae0cc3b7	46	" my_tramp2:"
0aec21cf	47	ASM_ENDBR
ae0cc3b7 SRV	48	" pushq %rbp\n"
ae0cc3b7 SRV	49	" movq %rsp, %rbp\n"
ee3e2469	50	CALL_DEPTH_ACCOUNT
ae0cc3b7 SRV	51	" call my_direct_func2\n"
ae0cc3b7 SRV	52	" leave\n"
b17c2baa	53	ASM_RET
9d907f1a	54	" .size my_tramp2, .-my_tramp2\n"
ae0cc3b7 SRV	55	" .popsection\n"
	56	);
	57
1254cfbc HC	58	#endif /* CONFIG_X86_64 */
	59
	60	#ifdef CONFIG_S390
	61
	62	asm (
	63	" .pushsection .text, \"ax\", @progbits\n"
	64	" .type my_tramp1, @function\n"
	65	" .globl my_tramp1\n"
	66	" my_tramp1:"
	67	" lgr %r1,%r15\n"
	68	" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
	69	" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
	70	" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
	71	" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
	72	" brasl %r14,my_direct_func1\n"
	73	" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
	74	" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
	75	" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
	76	" lgr %r1,%r0\n"
	77	" br %r1\n"
	78	" .size my_tramp1, .-my_tramp1\n"
	79	" .type my_tramp2, @function\n"
	80	" .globl my_tramp2\n"
	81	" my_tramp2:"
	82	" lgr %r1,%r15\n"
	83	" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
	84	" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
	85	" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
	86	" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
	87	" brasl %r14,my_direct_func2\n"
	88	" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
	89	" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
	90	" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
	91	" lgr %r1,%r0\n"
	92	" br %r1\n"
	93	" .size my_tramp2, .-my_tramp2\n"
	94	" .popsection\n"
	95	);
	96
	97	#endif /* CONFIG_S390 */
	98
22f367a6 YT	99	#ifdef CONFIG_LOONGARCH
	100
	101	asm (
	102	" .pushsection .text, \"ax\", @progbits\n"
	103	" .type my_tramp1, @function\n"
	104	" .globl my_tramp1\n"
	105	" my_tramp1:\n"
	106	" addi.d $sp, $sp, -16\n"
	107	" st.d $t0, $sp, 0\n"
	108	" st.d $ra, $sp, 8\n"
	109	" bl my_direct_func1\n"
	110	" ld.d $t0, $sp, 0\n"
	111	" ld.d $ra, $sp, 8\n"
	112	" addi.d $sp, $sp, 16\n"
	113	" jr $t0\n"
	114	" .size my_tramp1, .-my_tramp1\n"
	115
	116	" .type my_tramp2, @function\n"
	117	" .globl my_tramp2\n"
	118	" my_tramp2:\n"
	119	" addi.d $sp, $sp, -16\n"
	120	" st.d $t0, $sp, 0\n"
	121	" st.d $ra, $sp, 8\n"
	122	" bl my_direct_func2\n"
	123	" ld.d $t0, $sp, 0\n"
	124	" ld.d $ra, $sp, 8\n"
	125	" addi.d $sp, $sp, 16\n"
	126	" jr $t0\n"
	127	" .size my_tramp2, .-my_tramp2\n"
	128	" .popsection\n"
	129	);
	130
	131	#endif /* CONFIG_LOONGARCH */
	132
23edf483 FR	133	static struct ftrace_ops direct;
23edf483 FR	134
ae0cc3b7 SRV	135	static unsigned long my_tramp = (unsigned long)my_tramp1;
	136	static unsigned long tramps[2] = {
	137	(unsigned long)my_tramp1,
	138	(unsigned long)my_tramp2,
	139	};
	140
	141	static int simple_thread(void *arg)
	142	{
	143	static int t;
	144	int ret = 0;
	145
	146	while (!kthread_should_stop()) {
	147	set_current_state(TASK_INTERRUPTIBLE);
	148	schedule_timeout(2 * HZ);
	149
	150	if (ret)
	151	continue;
	152	t ^= 1;
da8bdfbd	153	ret = modify_ftrace_direct(&direct, tramps[t]);
ae0cc3b7 SRV	154	if (!ret)
	155	my_tramp = tramps[t];
	156	WARN_ON_ONCE(ret);
	157	}
	158
	159	return 0;
	160	}
	161
	162	static struct task_struct *simple_tsk;
	163
	164	static int __init ftrace_direct_init(void)
	165	{
	166	int ret;
	167
23edf483	168	ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0);
da8bdfbd	169	ret = register_ftrace_direct(&direct, my_tramp);
23edf483	170
ae0cc3b7 SRV	171	if (!ret)
	172	simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
	173	return ret;
	174	}
	175
	176	static void __exit ftrace_direct_exit(void)
	177	{
	178	kthread_stop(simple_tsk);
da8bdfbd	179	unregister_ftrace_direct(&direct, my_tramp, true);
ae0cc3b7 SRV	180	}
	181
	182	module_init(ftrace_direct_init);
	183	module_exit(ftrace_direct_exit);
	184
	185	MODULE_AUTHOR("Steven Rostedt");
da8bdfbd	186	MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()");
ae0cc3b7	187	MODULE_LICENSE("GPL");