aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/kernel/jump_label.c
blob: ea9d5f2f13efec411a79a0b43f003b29c06654d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
/*
 * jump label x86 support
 *
 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
 *
 */
#include <linux/jump_label.h>
#include <linux/memory.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/cpu.h>
#include <asm/kprobes.h>
#include <asm/alternative.h>

#ifdef HAVE_JUMP_LABEL

union jump_code_union {
	char code[JUMP_LABEL_NOP_SIZE];
	struct {
		char jump;
		int offset;
	} __attribute__((packed));
};

static void __jump_label_transform(struct jump_entry *entry,
				   enum jump_label_type type,
				   void *(*poker)(void *, const void *, size_t))
{
	union jump_code_union code;

	if (type == JUMP_LABEL_ENABLE) {
		code.jump = 0xe9;
		code.offset = entry->target -
				(entry->code + JUMP_LABEL_NOP_SIZE);
	} else
		memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);

	(*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
}

void arch_jump_label_transform(struct jump_entry *entry,
			       enum jump_label_type type)
{
	get_online_cpus();
	mutex_lock(&text_mutex);
	__jump_label_transform(entry, type, text_poke_smp);
	mutex_unlock(&text_mutex);
	put_online_cpus();
}

void arch_jump_label_transform_static(struct jump_entry *entry,
				      enum jump_label_type type)
{
	__jump_label_transform(entry, type, text_poke_early);
}

#endif