1 /*-
2 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Berkeley Software Design Inc's name may not be used to endorse or
13 * promote products derived from this software without specific prior
14 * written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * from: BSDI: wstate.h,v 1.4 1997/09/18 13:05:51 torek Exp
29 * $FreeBSD: releng/6.4/sys/sparc64/include/wstate.h 91246 2002-02-25 18:37:17Z jake $
30 */
31
32 #ifndef _MACHINE_WSTATE_H_
33 #define _MACHINE_WSTATE_H_
34
35 /*
36 * Window state register bits.
37 *
38 * There really are no bits per se, just the two fields WSTATE.NORMAL
39 * and WSTATE.OTHER. The rest is up to software.
40 *
41 * We use WSTATE_NORMAL to represent user mode or kernel mode saves
42 * (whichever is currently in effect) and WSTATE_OTHER to represent
43 * user mode saves (only).
44 *
45 * We use the low bit to suggest 32-bit mode, with the next bit set
46 * once we succeed in saving in some mode. That is, if the WSTATE_ASSUME
47 * bit is set, the spill or fill handler we use will be one that makes
48 * an assumption about the proper window-save mode. If the spill or
49 * fill fails with an alignment fault, the spill or fill op should
50 * take the `assume' bit away retry the instruction that caused the
51 * spill or fill. This will use the new %wstate, which will test for
52 * which mode to use. The alignment fault code helps us out here by
53 * resuming the spill vector at offset +70, where we are allowed to
54 * execute two instructions (i.e., write to %wstate and RETRY).
55 *
56 * If the ASSUME bit is not set when the alignment fault occurs, the
57 * given stack pointer is hopelessly wrong (and the spill, if it is a
58 * spill, should be done as a sort of "panic spill") -- so those two
59 * instructions will be a branch sequence.
60 *
61 * Note that locore.s assumes this same bit layout (since the translation
62 * from "bits" to "{spill,fill}_N_{normal,other}" is done in hardware).
63 *
64 * The value 0 is preferred for unknown to make it easy to start in
65 * unknown state and continue in whichever state unknown succeeds in --
66 * a successful "other" save, for instance, can just set %wstate to
67 * ASSUMExx << USERSHIFT and thus leave the kernel state "unknown".
68 *
69 * We also need values for managing the somewhat tricky transition from
70 * user to kernel and back, so we use the one remaining free bit to mean
71 * "although this looks like kernel mode, the window(s) involved are
72 * user windows and should be saved ASI_AIUP". Everything else is
73 * otherwise the same, but we need not bother with assumptions in this
74 * mode (we expect it to apply to at most one window spill or fill),
75 * i.e., WSTATE_TRANSITION can ignore WSTATE_ASSUME if it likes.
76 */
77
78 #define WSTATE_NORMAL_MASK 1 /* wstate normal minus transition */
79 #define WSTATE_OTHER_SHIFT 3 /* for wstate other / user */
80 #define WSTATE_OTHER_MASK /* wstate other minus nested */ \
81 (WSTATE_NORMAL_MASK << WSTATE_OTHER_SHIFT)
82
83 #define WSTATE_KERNEL 0 /* normal kernel wstate */
84 #define WSTATE_USER_64 0 /* normal 64bit user wstate */
85 #define WSTATE_USER_32 1 /* normal 32bit user wstate */
86
87 #define WSTATE_TRANSITION 2 /* if set, force user window */
88 #define WSTATE_NESTED /* if set, spill must not fault */ \
89 (WSTATE_TRANSITION << WSTATE_OTHER_SHIFT)
90
91 #endif /* !_MACHINE_WSTATE_H_ */
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