/*      $NetBSD: compat_13_machdep.c,v 1.27 2017/09/17 09:41:35 maxv Exp $      */

/*-
 * Copyright (c) 1996, 1997, 1998, 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: compat_13_machdep.c,v 1.27 2017/09/17 09:41:35 maxv Exp $");

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

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

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, context;
        struct trapframe *tf;
        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 (copyin((void *)scp, &context, sizeof(*scp)) != 0)
                return (EFAULT);

        /* Restore register context. */
        tf = l->l_md.md_regs;

        /*
         * Check for security violations.  If we're returning to
         * protected mode, the CPU will validate the segment registers
         * automatically and generate a trap on violations.  We handle
         * the trap, rather than doing all of the checking here.
         */
        if (((context.sc_eflags ^ tf->tf_eflags) & PSL_USERSTATIC) != 0 ||
            !USERMODE(context.sc_cs))
                return (EINVAL);

        tf->tf_gs = context.sc_gs;
        tf->tf_fs = context.sc_fs;              
        tf->tf_es = context.sc_es;
        tf->tf_ds = context.sc_ds;
        tf->tf_eflags &= ~PSL_USER;
        tf->tf_eflags |= context.sc_eflags & PSL_USER;

        tf->tf_edi = context.sc_edi;
        tf->tf_esi = context.sc_esi;
        tf->tf_ebp = context.sc_ebp;
        tf->tf_ebx = context.sc_ebx;
        tf->tf_edx = context.sc_edx;
        tf->tf_ecx = context.sc_ecx;
        tf->tf_eax = context.sc_eax;
        tf->tf_eip = context.sc_eip;
        tf->tf_cs = context.sc_cs;
        tf->tf_esp = context.sc_esp;
        tf->tf_ss = context.sc_ss;

        mutex_enter(p->p_lock);
        /* Restore signal stack. */
        if (context.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(&context.sc_mask, &mask);
        (void) sigprocmask1(l, SIG_SETMASK, &mask, 0);
        mutex_exit(p->p_lock);

        return (EJUSTRETURN);
}