/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

        .file   "vforkx.s"

#include "SYS.h"
#include <assym.h>

/*
 * pid = vforkx(flags);
 * syscall trap: forksys(2, flags)
 *
 * pid = vfork();
 * syscall trap: forksys(2, 0)
 *
 * From the syscall:
 * %o1 == 0 in parent process, %o1 == 1 in child process.
 * %o0 == pid of child in parent, %o0 == pid of parent in child.
 *
 * The child gets a zero return value.
 * The parent gets the pid of the child.
 */

/*
 * Note that since the SPARC architecture maintains stack maintence
 * information (return pc, sp, fp) in the register windows, both parent
 * and child can execute in a common address space without conflict.
 *
 * We block all blockable signals while performing the vfork() system call
 * trap.  This enables us to set curthread->ul_vfork safely, so that we
 * don't end up in a signal handler with curthread->ul_vfork set wrong.
 */

        ENTRY_NP(vforkx)
        ba      0f
        mov     %o0, %o5                /* flags */
        ENTRY_NP(vfork)
        clr     %o5                     /* flags = 0 */
0:
        mov     SIG_SETMASK, %o0        /* block all signals */
        set     MASKSET0, %o1
        set     MASKSET1, %o2
        set     MASKSET2, %o3
        set     MASKSET3, %o4
        SYSTRAP_RVAL1(lwp_sigmask)

        mov     %o5, %o1                /* flags */
        mov     2, %o0
        SYSTRAP_2RVALS(forksys)         /* vforkx(flags) */
        bcc,a,pt %icc, 1f
        tst     %o1

        mov     %o0, %o5                /* save the vfork() error number */

        mov     SIG_SETMASK, %o0        /* reinstate signals */
        ld      [%g7 + UL_SIGMASK], %o1
        ld      [%g7 + UL_SIGMASK + 4], %o2
        ld      [%g7 + UL_SIGMASK + 8], %o3
        ld      [%g7 + UL_SIGMASK + 12], %o4
        SYSTRAP_RVAL1(lwp_sigmask)

        ba      __cerror
        mov     %o5, %o0                /* restore the vfork() error number */

1:
        /*
         * To determine if we are (still) a child of vfork(), the child
         * increments curthread->ul_vfork by one and the parent decrements
         * it by one.  If the result is zero, then we are not a child of
         * vfork(), else we are.  We do this to deal with the case of
         * a vfork() child calling vfork().
         */
        bnz,pt  %icc, 2f
        ld      [%g7 + UL_VFORK], %g1
        brnz,a,pt %g1, 3f               /* don't let it go negative */
        sub     %g1, 1, %g1             /* curthread->ul_vfork--; */
        ba,a    3f
2:
        clr     %o0                     /* zero the return value in the child */
        add     %g1, 1, %g1             /* curthread->ul_vfork++; */
3:
        st      %g1, [%g7 + UL_VFORK]
        /*
         * Clear the schedctl interface in both parent and child.
         * (The child might have modified the parent.)
         */
        stn     %g0, [%g7 + UL_SCHEDCTL]
        stn     %g0, [%g7 + UL_SCHEDCTL_CALLED]
        mov     %o0, %o5                /* save the vfork() return value */

        mov     SIG_SETMASK, %o0        /* reinstate signals */
        ld      [%g7 + UL_SIGMASK], %o1
        ld      [%g7 + UL_SIGMASK + 4], %o2
        ld      [%g7 + UL_SIGMASK + 8], %o3
        ld      [%g7 + UL_SIGMASK + 12], %o4
        SYSTRAP_RVAL1(lwp_sigmask)

        retl
        mov     %o5, %o0                /* restore the vfork() return value */
        SET_SIZE(vfork)
        SET_SIZE(vforkx)