/*      $OpenBSD: process.S,v 1.27 2022/12/06 18:50:59 guenther Exp $   */
/*
 * Copyright (c) 1996 Nivas Madhur
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Nivas Madhur.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 */

#include "assym.h"
#include <machine/asm.h>
#include <machine/psl.h>

/*
 * void cpu_switchto(struct proc *oldproc, struct proc *newproc)
 *
 * Switch context from oldproc to newproc. oldproc may be NULL if there is
 * no need to save the current context.
 *
 * Note that this code assumes that oldproc == curproc if not NULL.
 */
ENTRY(cpu_switchto)
        /*
         * Save state of previous process in its pcb if required.
         */
        bcnd    eq0,  %r2, 1f

        ldcr    %r2,  CPU
        ld      %r2,  %r2,  CI_CURPCB
        st      %r1,  %r2,  PCB_PC              /* save return address */
        bsr     __savectx
        /* note that we don't need to recover r1 at this point */

        /* inline pmap_deactivate(oldproc) */
        ldcr    %r11, CPU
        st      %r0,  %r11, CI_CURPMAP

1:
        ldcr    %r2, PSR
        set     %r2, %r2, 1<PSR_INTERRUPT_DISABLE_BIT>
        stcr    %r2, PSR
        FLUSH_PIPELINE

        ldcr    %r11, CPU
        st      %r3,  %r11, CI_CURPROC                  /* curproc = newproc */

        or      %r2,  %r0,  SONPROC
        st.b    %r2,  %r3,  P_STAT
#ifdef MULTIPROCESSOR
        st      %r11, %r3,  P_CPU                       /* p->p_cpu = curcpu */
#endif
        ld      %r2,  %r3,  P_ADDR
        st      %r2,  %r11, CI_CURPCB                   /* curpcb = p->p_addr */

        bsr.n   pmap_activate                   /* pmap_activate(newproc) */
         or     %r2, %r0, %r3

        ldcr    %r2, PSR
        clr     %r2, %r2, 1<PSR_INTERRUPT_DISABLE_BIT>
        stcr    %r2, PSR
        FLUSH_PIPELINE

        ldcr    %r10,  CPU
        ld      %r10,  %r10, CI_CURPCB

        /* restore from the current context */
        ld.d    %r2,  %r10, PCB_FCR62
        fstcr   %r2,  %fcr62
        fstcr   %r3,  %fcr63
        ld      %r1,  %r10, PCB_PC
        ld.d    %r14, %r10, PCB_R14
        ld.d    %r16, %r10, PCB_R16
        ld.d    %r18, %r10, PCB_R18
        ld.d    %r20, %r10, PCB_R20
        ld.d    %r22, %r10, PCB_R22
        ld.d    %r24, %r10, PCB_R24
        ld.d    %r26, %r10, PCB_R26
        ld.d    %r28, %r10, PCB_R28
        jmp.n   %r1
         ld.d   %r30, %r10, PCB_R30     /* restore frame pointer & stack */

/*
 * savectx(pcb)
 * Update pcb, saving current processor state.
 */
ENTRY(savectx)
        /*
         * Save preserved general register set.
         */
        st      %r1,  %r2,  PCB_PC              /* save return address */
ASLOCAL(__savectx)
        st.d    %r14, %r2,  PCB_R14
        st.d    %r16, %r2,  PCB_R16
        st.d    %r18, %r2,  PCB_R18
        st.d    %r20, %r2,  PCB_R20
        st.d    %r22, %r2,  PCB_R22
        st.d    %r24, %r2,  PCB_R24
        st.d    %r26, %r2,  PCB_R26
        st.d    %r28, %r2,  PCB_R28
        st.d    %r30, %r2,  PCB_R30     /* save frame pointer & stack pointer */

        /*
         * Save FP state.
         */
        fldcr   %r4,  %fcr62
        fldcr   %r5,  %fcr63
        jmp.n   %r1
         st.d   %r4,  %r2, PCB_FCR62