1/*	$OpenBSD: pcb.h,v 1.11 2022/10/21 18:55:42 miod Exp $	*/
2/*	$NetBSD: pcb.h,v 1.7 2000/12/29 17:12:05 eeh Exp $ */
3
4/*
5 * Copyright (c) 1992, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * This software was developed by the Computer Systems Engineering group
9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
10 * contributed to Berkeley.
11 *
12 * All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 *	This product includes software developed by the University of
15 *	California, Lawrence Berkeley Laboratory.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 * 3. Neither the name of the University nor the names of its contributors
26 *    may be used to endorse or promote products derived from this software
27 *    without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 *	@(#)pcb.h	8.1 (Berkeley) 6/11/93
42 */
43
44#ifndef _MACHINE_PCB_H_
45#define _MACHINE_PCB_H_
46
47#include <machine/reg.h>
48
49#ifdef notyet
50#define	PCB_MAXWIN	32	/* architectural limit */
51#else
52#define	PCB_MAXWIN	8	/* worried about u area sizes ... */
53#endif
54
55/*
56 * SPARC Process Control Block.
57 *
58 * pcb_uw is positive if there are any user windows that are
59 * are currently in the CPU windows rather than on the user
60 * stack.  Whenever we are running in the kernel with traps
61 * enabled, we decrement pcb_uw for each ``push'' of a CPU
62 * register window into the stack, and we increment it for
63 * each ``pull'' from the stack into the CPU.  (If traps are
64 * disabled, or if we are in user mode, pcb_uw is junk.)
65 *
66 * To ease computing pcb_uw on traps from user mode, we keep track
67 * of the log base 2 of the single bit that is set in %wim.
68 *
69 * If an overflow occurs while the associated user stack pages
70 * are invalid (paged out), we have to store the registers
71 * in a page that is locked in core while the process runs,
72 * i.e., right here in the pcb.  We also need the stack pointer
73 * for the last such window (but only the last, as the others
74 * are in each window) and the count of windows saved.  We
75 * cheat by having a whole window structure for that one %sp.
76 * Thus, to save window pcb_rw[i] to memory, we write it at
77 * pcb_rw[i + 1].rw_in[6].
78 *
79 * pcb_nsaved has three `kinds' of values.  If 0, it means no
80 * registers are in the PCB (though if pcb_uw is positive,
81 * there may be the next time you look).  If positive, it means
82 * there are no user registers in the CPU, but there are some
83 * saved in pcb_rw[].  As a special case, traps that needed
84 * assistance to pull user registers from the stack also store
85 * the registers in pcb_rw[], and set pcb_nsaved to -1.  This
86 * special state is normally short-term: it can only last until the
87 * trap returns, and it can never persist across entry to user code.
88 */
89/*
90 * v9 addendum:
91 *
92 * Window handling between v8 and v9 has changed somewhat.  There
93 * is no %wim.  Instead, we have a %cwp, %cansave, %canrestore,
94 * %cleanwin, and %otherwin.  By definition:
95 *
96 *	 %cansave + %canrestore + %otherwin = NWINDOWS - 2
97 *
98 * In addition, %cleanwin >= %canrestore since restorable windows
99 * are considered clean.  This means that by storing %canrestore
100 * and %otherwin, we should be able to compute the values of all
101 * the other registers.
102 *
103 * The only other register we need to save is %cwp because it cannot
104 * be trivially computed from the other registers.  The %cwp is
105 * stored in the %tstate register, but if the machine was in a register
106 * window spill/fill handler, the value of that %cwp may be off by
107 * as much as 2 register windows.  We will also store %cwp.  [We will
108 * try to steal pcb_uw or pcb_nsaved for this purpose eventually.]
109 *
110 * To calculate what registers are in the pcb, start with pcb_cwp
111 * and proceed to (pcb_cwp - pcb_canrestore) % NWINDOWS.  These should
112 * be saved to their appropriate register windows.  The client routine
113 * (trap handler) is responsible for saving pcb_cwp + 1 [%o1-%o7] in
114 * the trap frame or on the stack.
115 *
116 *
117 * Even more addendum:
118 *
119 * With the new system for keeping track of register windows we don't
120 * care about anything other than pcb_uw which keeps track of how many
121 * full windows we have.  As soon as a flush traps, we dump all user
122 * windows to the pcb, handle the fault, then restore all user windows.
123 *
124 * XXX we are using pcb_nsaved as the counter.  pcb_uw is still a mask.
125 * change this as soon as the new scheme is debugged.
126 */
127struct pcb {
128	u_int64_t	pcb_sp;		/* sp (%o6) when switch() was called */
129	u_int64_t	pcb_pc;		/* pc (%o7) when switch() was called */
130	caddr_t	pcb_onfault;	/* for copyin/out */
131	short	pcb_pstate;	/* %pstate when switch() was called -- may be useful if we support multiple memory models */
132	char	pcb_nsaved;	/* number of windows saved in pcb */
133
134	/* The rest is probably not needed except for pcb_rw */
135	char	pcb_cwp;	/* %cwp when switch() was called */
136	char	pcb_pil;	/* %pil when switch() was called -- probably not needed */
137
138	const char *lastcall;	/* DEBUG -- name of last system call */
139	u_int64_t	pcb_wcookie;
140
141	/* the following MUST be aligned on a 64-bit boundary */
142	struct	rwindow pcb_rw[PCB_MAXWIN];	/* saved windows */
143	u_int64_t	pcb_rwsp[PCB_MAXWIN];
144};
145
146#ifndef _KERNEL
147/* Let gdb compile.  We need fancier macros to make these make sense. */
148#define pcb_psr	pcb_pstate
149#define pcb_wim	pcb_cwp
150#endif /* _KERNEL */
151
152#endif /* _MACHINE_PCB_H_ */
153