1 /*
2 * jump label x86 support
3 *
4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5 *
6 */
7 #include <linux/jump_label.h>
8 #include <linux/memory.h>
9 #include <linux/uaccess.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/jhash.h>
13 #include <linux/cpu.h>
14 #include <asm/kprobes.h>
15 #include <asm/alternative.h>
16
17 #ifdef HAVE_JUMP_LABEL
18
19 union jump_code_union {
20 char code[JUMP_LABEL_NOP_SIZE];
21 struct {
22 char jump;
23 int offset;
24 } __attribute__((packed));
25 };
26
__jump_label_transform(struct jump_entry * entry,enum jump_label_type type,void * (* poker)(void *,const void *,size_t))27 static void __jump_label_transform(struct jump_entry *entry,
28 enum jump_label_type type,
29 void *(*poker)(void *, const void *, size_t))
30 {
31 union jump_code_union code;
32
33 if (type == JUMP_LABEL_ENABLE) {
34 code.jump = 0xe9;
35 code.offset = entry->target -
36 (entry->code + JUMP_LABEL_NOP_SIZE);
37 } else
38 memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
39
40 (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
41 }
42
arch_jump_label_transform(struct jump_entry * entry,enum jump_label_type type)43 void arch_jump_label_transform(struct jump_entry *entry,
44 enum jump_label_type type)
45 {
46 get_online_cpus();
47 mutex_lock(&text_mutex);
48 __jump_label_transform(entry, type, text_poke_smp);
49 mutex_unlock(&text_mutex);
50 put_online_cpus();
51 }
52
arch_jump_label_transform_static(struct jump_entry * entry,enum jump_label_type type)53 __init_or_module void arch_jump_label_transform_static(struct jump_entry *entry,
54 enum jump_label_type type)
55 {
56 __jump_label_transform(entry, type, text_poke_early);
57 }
58
59 #endif
60