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