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  * SPDX-License-Identifier:	GPL-2.0+
14  */
15 
16 #ifndef __X86_CONTROL_REGS_H
17 #define __X86_CONTROL_REGS_H
18 
19 /*
20  * The memory clobber prevents the GCC from reordering the read/write order
21  * of CR0
22 */
23 static inline unsigned long read_cr0(void)
24 {
25 	unsigned long val;
26 
27 	asm volatile ("movl %%cr0, %0" : "=r" (val) : : "memory");
28 	return val;
29 }
30 
31 static inline void write_cr0(unsigned long val)
32 {
33 	asm volatile ("movl %0, %%cr0" : : "r" (val) : "memory");
34 }
35 
36 static inline unsigned long read_cr2(void)
37 {
38 	unsigned long val;
39 
40 	asm volatile("mov %%cr2,%0\n\t" : "=r" (val) : : "memory");
41 	return val;
42 }
43 
44 static inline unsigned long read_cr3(void)
45 {
46 	unsigned long val;
47 
48 	asm volatile("mov %%cr3,%0\n\t" : "=r" (val) : : "memory");
49 	return val;
50 }
51 
52 static inline unsigned long read_cr4(void)
53 {
54 	unsigned long val;
55 
56 	asm volatile("mov %%cr4,%0\n\t" : "=r" (val) : : "memory");
57 	return val;
58 }
59 
60 static inline unsigned long get_debugreg(int regno)
61 {
62 	unsigned long val = 0;  /* Damn you, gcc! */
63 
64 	switch (regno) {
65 	case 0:
66 		asm("mov %%db0, %0" : "=r" (val));
67 		break;
68 	case 1:
69 		asm("mov %%db1, %0" : "=r" (val));
70 		break;
71 	case 2:
72 		asm("mov %%db2, %0" : "=r" (val));
73 		break;
74 	case 3:
75 		asm("mov %%db3, %0" : "=r" (val));
76 		break;
77 	case 6:
78 		asm("mov %%db6, %0" : "=r" (val));
79 		break;
80 	case 7:
81 		asm("mov %%db7, %0" : "=r" (val));
82 		break;
83 	default:
84 		val = 0;
85 	}
86 	return val;
87 }
88 
89 #endif
90