9dcbb8e88d
Debuggers may need to change PSL_RF. Note that tf_eflags is already stored in the signal context during signal handling and PSL_RF previously could be modified via sigreturn, so this change should not provide any new ability to userspace. For background see the thread at: http://lists.freebsd.org/pipermail/freebsd-i386/2007-September/005910.html Reviewed by: jhb, kib Sponsored by: DARPA, AFRL
93 lines
4.0 KiB
C
93 lines
4.0 KiB
C
/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* William Jolitz.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)psl.h 5.2 (Berkeley) 1/18/91
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* $FreeBSD$
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*/
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#ifndef _MACHINE_PSL_H_
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#define _MACHINE_PSL_H_
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/*
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* 386 processor status longword.
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*/
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#define PSL_C 0x00000001 /* carry bit */
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#define PSL_PF 0x00000004 /* parity bit */
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#define PSL_AF 0x00000010 /* bcd carry bit */
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#define PSL_Z 0x00000040 /* zero bit */
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#define PSL_N 0x00000080 /* negative bit */
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#define PSL_T 0x00000100 /* trace enable bit */
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#define PSL_I 0x00000200 /* interrupt enable bit */
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#define PSL_D 0x00000400 /* string instruction direction bit */
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#define PSL_V 0x00000800 /* overflow bit */
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#define PSL_IOPL 0x00003000 /* i/o privilege level */
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#define PSL_NT 0x00004000 /* nested task bit */
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#define PSL_RF 0x00010000 /* resume flag bit */
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#define PSL_VM 0x00020000 /* virtual 8086 mode bit */
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#define PSL_AC 0x00040000 /* alignment checking */
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#define PSL_VIF 0x00080000 /* virtual interrupt enable */
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#define PSL_VIP 0x00100000 /* virtual interrupt pending */
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#define PSL_ID 0x00200000 /* identification bit */
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/*
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* The i486 manual says that we are not supposed to change reserved flags,
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* but this is too much trouble since the reserved flags depend on the cpu
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* and setting them to their historical values works in practice.
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*/
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#define PSL_RESERVED_DEFAULT 0x00000002
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/*
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* Initial flags for kernel and user mode. The kernel later inherits
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* PSL_I and some other flags from user mode.
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*/
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#define PSL_KERNEL PSL_RESERVED_DEFAULT
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#define PSL_USER (PSL_RESERVED_DEFAULT | PSL_I)
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/*
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* Bits that can be changed in user mode on 486's. We allow these bits
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* to be changed using ptrace(), sigreturn() and procfs. Setting PS_NT
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* is undesirable but it may as well be allowed since users can inflict
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* it on the kernel directly. Changes to PSL_AC are silently ignored on
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* 386's.
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*
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* Users are allowed to change the privileged flag PSL_RF. The cpu sets PSL_RF
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* in tf_eflags for faults. Debuggers should sometimes set it there too.
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* tf_eflags is kept in the signal context during signal handling and there is
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* no other place to remember it, so the PSL_RF bit may be corrupted by the
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* signal handler without us knowing. Corruption of the PSL_RF bit at worst
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* causes one more or one less debugger trap, so allowing it is fairly
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* harmless.
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*/
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#define PSL_USERCHANGE (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_T \
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| PSL_D | PSL_V | PSL_NT | PSL_RF | PSL_AC | PSL_ID)
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#endif /* !_MACHINE_PSL_H_ */
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