1 /*
2  * Copyright (c) 2012 The Chromium OS Authors.
3  *
4  * (C) Copyright 2008-2011
5  * Graeme Russ, <graeme.russ@gmail.com>
6  *
7  * (C) Copyright 2002
8  * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
9  *
10  * Portions of this file are derived from the Linux kernel source
11  *  Copyright (C) 1991, 1992  Linus Torvalds
12  *
13  * See file CREDITS for list of people who contributed to this
14  * project.
15  *
16  * This program is free software; you can redistribute it and/or
17  * modify it under the terms of the GNU General Public License as
18  * published by the Free Software Foundation; either version 2 of
19  * the License, or (at your option) any later version.
20  *
21  * This program is distributed in the hope that it will be useful,
22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24  * GNU General Public License for more details.
25  *
26  * You should have received a copy of the GNU General Public License
27  * along with this program; if not, write to the Free Software
28  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
29  * MA 02111-1307 USA
30  */
31 
32 #ifndef __X86_CONTROL_REGS_H
33 #define __X86_CONTROL_REGS_H
34 
35 /*
36  * The memory clobber prevents the GCC from reordering the read/write order
37  * of CR0
38 */
39 static inline unsigned long read_cr0(void)
40 {
41 	unsigned long val;
42 
43 	asm volatile ("movl %%cr0, %0" : "=r" (val) : : "memory");
44 	return val;
45 }
46 
47 static inline void write_cr0(unsigned long val)
48 {
49 	asm volatile ("movl %0, %%cr0" : : "r" (val) : "memory");
50 }
51 
52 static inline unsigned long read_cr2(void)
53 {
54 	unsigned long val;
55 
56 	asm volatile("mov %%cr2,%0\n\t" : "=r" (val) : : "memory");
57 	return val;
58 }
59 
60 static inline unsigned long read_cr3(void)
61 {
62 	unsigned long val;
63 
64 	asm volatile("mov %%cr3,%0\n\t" : "=r" (val) : : "memory");
65 	return val;
66 }
67 
68 static inline unsigned long read_cr4(void)
69 {
70 	unsigned long val;
71 
72 	asm volatile("mov %%cr4,%0\n\t" : "=r" (val) : : "memory");
73 	return val;
74 }
75 
76 static inline unsigned long get_debugreg(int regno)
77 {
78 	unsigned long val = 0;  /* Damn you, gcc! */
79 
80 	switch (regno) {
81 	case 0:
82 		asm("mov %%db0, %0" : "=r" (val));
83 		break;
84 	case 1:
85 		asm("mov %%db1, %0" : "=r" (val));
86 		break;
87 	case 2:
88 		asm("mov %%db2, %0" : "=r" (val));
89 		break;
90 	case 3:
91 		asm("mov %%db3, %0" : "=r" (val));
92 		break;
93 	case 6:
94 		asm("mov %%db6, %0" : "=r" (val));
95 		break;
96 	case 7:
97 		asm("mov %%db7, %0" : "=r" (val));
98 		break;
99 	default:
100 		val = 0;
101 	}
102 	return val;
103 }
104 
105 #endif
106