/*      $NetBSD: compat_13_machdep.c,v 1.15 2011/02/08 20:20:16 rmind Exp $     */

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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.
 *
 *      from: Utah Hdr: machdep.c 1.74 92/12/20
 *      from: @(#)machdep.c     8.10 (Berkeley) 4/20/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: compat_13_machdep.c,v 1.15 2011/02/08 20:20:16 rmind Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/signal.h>
#include <sys/signalvar.h>

#include <sys/mount.h>
#include <sys/syscallargs.h>

#include <compat/sys/signal.h>
#include <compat/sys/signalvar.h>

#include <machine/cpu.h>
#include <machine/reg.h>

/*
 * System call to cleanup state after a signal
 * has been taken.  Reset signal mask and
 * stack state from context left by sendsig (above).
 * Return to previous pc and psl as specified by
 * context left by sendsig. Check carefully to
 * make sure that the user has not modified the
 * psl to gain improper privileges or to cause
 * a machine fault.
 */
int
compat_13_sys_sigreturn(struct lwp *l, const struct compat_13_sys_sigreturn_args *uap, register_t *retval)
{
        /* {
                syscallarg(struct sigcontext13 *) sigcntxp;
        } */
        struct proc *p = l->l_proc;
        struct sigcontext13 *scp;
        struct frame *frame;
        struct sigcontext13 tsigc;
        sigset_t mask;

        /*
         * The trampoline code hands us the context.
         * It is unsafe to keep track of it ourselves, in the event that a
         * program jumps out of a signal handler.
         */
        scp = SCARG(uap, sigcntxp);
        if ((int)scp & 1)
                return EINVAL;

        if (copyin(scp, &tsigc, sizeof(tsigc)) != 0)
                return EFAULT;
        scp = &tsigc;

        /* Make sure the user isn't pulling a fast one on us! */
        if ((scp->sc_ps & (PSL_MBZ|PSL_IPL|PSL_S)) != 0)
                return EINVAL;

        /* Restore register context. */
        frame = (struct frame *)l->l_md.md_regs;

        /*
         * We only support restoring the sigcontext13 in this call.
         * We are not called from the sigcode (per sendsig()), so
         * we will not have a sigstate to restore.
         */
        if (scp->sc_ap != 0)
                return EINVAL;

        /*
         * Restore the user supplied information.
         * This should be at the last so that the error (EINVAL)
         * is reported to the sigreturn caller, not to the
         * jump destination.
         */

        frame->f_regs[SP] = scp->sc_sp;
        frame->f_regs[A6] = scp->sc_fp;
        frame->f_pc = scp->sc_pc;
        frame->f_sr = scp->sc_ps;

        mutex_enter(p->p_lock);

        /* Restore signal stack. */
        if (scp->sc_onstack & SS_ONSTACK)
                l->l_sigstk.ss_flags |= SS_ONSTACK;
        else
                l->l_sigstk.ss_flags &= ~SS_ONSTACK;

        /* Restore signal mask. */
        native_sigset13_to_sigset(&scp->sc_mask, &mask);
        (void)sigprocmask1(l, SIG_SETMASK, &mask, 0);

        mutex_exit(p->p_lock);

        return EJUSTRETURN;
}