xref: /freebsd/sys/x86/include/psl.h (revision 640235e2c2ba32947f7c59d168437ffa1280f1e6)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * William Jolitz.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	from: @(#)psl.h	5.2 (Berkeley) 1/18/91
33  * $FreeBSD$
34  */
35 
36 #ifndef _MACHINE_PSL_H_
37 #define	_MACHINE_PSL_H_
38 
39 /*
40  * 386 processor status longword.
41  */
42 #define	PSL_C		0x00000001	/* carry bit */
43 #define	PSL_PF		0x00000004	/* parity bit */
44 #define	PSL_AF		0x00000010	/* bcd carry bit */
45 #define	PSL_Z		0x00000040	/* zero bit */
46 #define	PSL_N		0x00000080	/* negative bit */
47 #define	PSL_T		0x00000100	/* trace enable bit */
48 #define	PSL_I		0x00000200	/* interrupt enable bit */
49 #define	PSL_D		0x00000400	/* string instruction direction bit */
50 #define	PSL_V		0x00000800	/* overflow bit */
51 #define	PSL_IOPL	0x00003000	/* i/o privilege level */
52 #define	PSL_NT		0x00004000	/* nested task bit */
53 #define	PSL_RF		0x00010000	/* resume flag bit */
54 #define	PSL_VM		0x00020000	/* virtual 8086 mode bit */
55 #define	PSL_AC		0x00040000	/* alignment checking */
56 #define	PSL_VIF		0x00080000	/* virtual interrupt enable */
57 #define	PSL_VIP		0x00100000	/* virtual interrupt pending */
58 #define	PSL_ID		0x00200000	/* identification bit */
59 
60 /*
61  * The i486 manual says that we are not supposed to change reserved flags,
62  * but this is too much trouble since the reserved flags depend on the cpu
63  * and setting them to their historical values works in practice.
64  */
65 #define	PSL_RESERVED_DEFAULT	0x00000002
66 
67 /*
68  * Initial flags for kernel and user mode.  The kernel later inherits
69  * PSL_I and some other flags from user mode.
70  */
71 #define	PSL_KERNEL	PSL_RESERVED_DEFAULT
72 #define	PSL_USER	(PSL_RESERVED_DEFAULT | PSL_I)
73 
74 /*
75  * Bits that can be changed in user mode on 486's.  We allow these bits
76  * to be changed using ptrace(), sigreturn() and procfs.  Setting PS_NT
77  * is undesirable but it may as well be allowed since users can inflict
78  * it on the kernel directly.  Changes to PSL_AC are silently ignored on
79  * 386's.
80  *
81  * Users are allowed to change the privileged flag PSL_RF.  The cpu sets PSL_RF
82  * in tf_eflags for faults.  Debuggers should sometimes set it there too.
83  * tf_eflags is kept in the signal context during signal handling and there is
84  * no other place to remember it, so the PSL_RF bit may be corrupted by the
85  * signal handler without us knowing.  Corruption of the PSL_RF bit at worst
86  * causes one more or one less debugger trap, so allowing it is fairly
87  * harmless.
88  */
89 #define	PSL_USERCHANGE (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_T \
90 			| PSL_D | PSL_V | PSL_NT | PSL_RF | PSL_AC | PSL_ID)
91 
92 #endif /* !_MACHINE_PSL_H_ */
93