LibertyBSD_kernel/sys/arch/sparc/include/pcb.h

/*	$OpenBSD: pcb.h,v 1.7 2015/05/05 02:13:47 guenther Exp $	*/
/*	$NetBSD: pcb.h,v 1.4 1995/03/28 18:19:56 jtc Exp $ */

/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Lawrence Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)pcb.h	8.1 (Berkeley) 6/11/93
 */

#ifndef _MACHINE_PCB_H_
#define _MACHINE_PCB_H_

#include <machine/reg.h>

#ifdef notyet
#define	PCB_MAXWIN	32	/* architectural limit */
#else
#define	PCB_MAXWIN	8	/* worried about u area sizes ... */
#endif

/*
 * SPARC Process Control Block.
 *
 * pcb_uw is positive if there are any user windows that are
 * are currently in the CPU windows rather than on the user
 * stack.  Whenever we are running in the kernel with traps
 * enabled, we decrement pcb_uw for each ``push'' of a CPU
 * register window into the stack, and we increment it for
 * each ``pull'' from the stack into the CPU.  (If traps are
 * disabled, or if we are in user mode, pcb_uw is junk.)
 *
 * To ease computing pcb_uw on traps from user mode, we keep track
 * of the log base 2 of the single bit that is set in %wim.
 *
 * If an overflow occurs while the associated user stack pages
 * are invalid (paged out), we have to store the registers
 * in a page that is locked in core while the process runs,
 * i.e., right here in the pcb.  We also need the stack pointer
 * for the last such window (but only the last, as the others
 * are in each window) and the count of windows saved.  We
 * cheat by having a whole window structure for that one %sp.
 * Thus, to save window pcb_rw[i] to memory, we write it at
 * pcb_rw[i + 1].rw_in[6].
 *
 * pcb_nsaved has three `kinds' of values.  If 0, it means no
 * registers are in the PCB (though if pcb_uw is positive,
 * there may be the next time you look).  If positive, it means
 * there are no user registers in the CPU, but there are some
 * saved in pcb_rw[].  As a special case, traps that needed
 * assistance to pull user registers from the stack also store
 * the registers in pcb_rw[], and set pcb_nsaved to -1.  This
 * special state is normally short-term: it can only last until the
 * trap returns, and it can never persist across entry to user code.
 */
struct pcb {
	int	pcb_sp;		/* sp (%o6) when switch() was called */
	int	pcb_pc;		/* pc (%o7) when switch() was called */
	int	pcb_psr;	/* %psr when switch() was called */

	caddr_t	pcb_onfault;	/* for copyin/out */

	int	pcb_uw;		/* user windows inside CPU */
	int	pcb_wim;	/* log2(%wim) */
	int	pcb_nsaved;	/* number of windows saved in pcb */

#ifdef notdef
	int	pcb_winof;	/* number of window overflow traps */
	int	pcb_winuf;	/* number of window underflow traps */
#endif
	u_int32_t pcb_wcookie;	/* StackGhost cookie (must be unsigned) */

	/* the following MUST be aligned on a doubleword boundary */
	struct	rwindow pcb_rw[PCB_MAXWIN];	/* saved windows */
};

#ifdef _KERNEL
extern struct pcb *cpcb;
#endif /* _KERNEL */

#endif