93 lines
4.4 KiB
C
93 lines
4.4 KiB
C
/*-
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* Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
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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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* 3. Berkeley Software Design Inc's name may not be used to endorse or
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* promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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: BSDI: wstate.h,v 1.4 1997/09/18 13:05:51 torek Exp
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* $FreeBSD$
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*/
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#ifndef _MACHINE_WSTATE_H_
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#define _MACHINE_WSTATE_H_
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/*
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* Window state register bits.
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*
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* There really are no bits per se, just the two fields WSTATE.NORMAL
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* and WSTATE.OTHER. The rest is up to software.
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*
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* We use WSTATE_NORMAL to represent user mode or kernel mode saves
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* (whichever is currently in effect) and WSTATE_OTHER to represent
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* user mode saves (only).
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*
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* We use the low bit to suggest 32-bit mode, with the next bit set
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* once we succeed in saving in some mode. That is, if the WSTATE_ASSUME
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* bit is set, the spill or fill handler we use will be one that makes
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* an assumption about the proper window-save mode. If the spill or
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* fill fails with an alignment fault, the spill or fill op should
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* take the `assume' bit away retry the instruction that caused the
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* spill or fill. This will use the new %wstate, which will test for
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* which mode to use. The alignment fault code helps us out here by
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* resuming the spill vector at offset +70, where we are allowed to
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* execute two instructions (i.e., write to %wstate and RETRY).
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*
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* If the ASSUME bit is not set when the alignment fault occurs, the
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* given stack pointer is hopelessly wrong (and the spill, if it is a
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* spill, should be done as a sort of "panic spill") -- so those two
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* instructions will be a branch sequence.
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*
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* Note that locore.s assumes this same bit layout (since the translation
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* from "bits" to "{spill,fill}_N_{normal,other}" is done in hardware).
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*
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* The value 0 is preferred for unknown to make it easy to start in
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* unknown state and continue in whichever state unknown succeeds in --
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* a successful "other" save, for instance, can just set %wstate to
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* ASSUMExx << USERSHIFT and thus leave the kernel state "unknown".
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*
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* We also need values for managing the somewhat tricky transition from
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* user to kernel and back, so we use the one remaining free bit to mean
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* "although this looks like kernel mode, the window(s) involved are
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* user windows and should be saved ASI_AIUP". Everything else is
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* otherwise the same, but we need not bother with assumptions in this
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* mode (we expect it to apply to at most one window spill or fill),
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* i.e., WSTATE_TRANSITION can ignore WSTATE_ASSUME if it likes.
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*/
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#define WSTATE_32BIT 1 /* if set, probably 32-bit mode */
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#define WSTATE_ASSUME 2 /* if set, assume 32 or 64 */
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#define WSTATE_TRANSITION 4 /* if set, force user window */
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#define WSTATE_TEST64 0 /* test, but anticipate 64-bit mode */
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#define WSTATE_TEST32 1 /* test, but anticipate 32-bit mode */
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#define WSTATE_ASSUME64 2 /* assume 64-bit mode */
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#define WSTATE_ASSUME32 3 /* assume 32-bit mode */
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#define WSTATE_NORMAL_MASK 3 /* wstate normal minus transition */
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#define WSTATE_OTHER_SHIFT 3 /* for wstate other / user */
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#define WSTATE_KERNEL 0 /* normal kernel wstate */
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#endif /* !_MACHINE_WSTATE_H_ */
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