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      1 /*	$NetBSD: compat_13_machdep.c,v 1.27 2017/09/17 09:41:35 maxv Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1996, 1997, 1998, 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Charles M. Hannum.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: compat_13_machdep.c,v 1.27 2017/09/17 09:41:35 maxv Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/systm.h>
     37 #include <sys/signalvar.h>
     38 #include <sys/kernel.h>
     39 #include <sys/proc.h>
     40 #include <sys/mount.h>
     41 #include <sys/syscallargs.h>
     42 
     43 #include <compat/sys/signal.h>
     44 #include <compat/sys/signalvar.h>
     45 
     46 int
     47 compat_13_sys_sigreturn(struct lwp *l, const struct compat_13_sys_sigreturn_args *uap, register_t *retval)
     48 {
     49 	/* {
     50 		syscallarg(struct sigcontext13 *) sigcntxp;
     51 	} */
     52 	struct proc *p = l->l_proc;
     53 	struct sigcontext13 *scp, context;
     54 	struct trapframe *tf;
     55 	sigset_t mask;
     56 
     57 	/*
     58 	 * The trampoline code hands us the context.
     59 	 * It is unsafe to keep track of it ourselves, in the event that a
     60 	 * program jumps out of a signal handler.
     61 	 */
     62 	scp = SCARG(uap, sigcntxp);
     63 	if (copyin((void *)scp, &context, sizeof(*scp)) != 0)
     64 		return (EFAULT);
     65 
     66 	/* Restore register context. */
     67 	tf = l->l_md.md_regs;
     68 
     69 	/*
     70 	 * Check for security violations.  If we're returning to
     71 	 * protected mode, the CPU will validate the segment registers
     72 	 * automatically and generate a trap on violations.  We handle
     73 	 * the trap, rather than doing all of the checking here.
     74 	 */
     75 	if (((context.sc_eflags ^ tf->tf_eflags) & PSL_USERSTATIC) != 0 ||
     76 	    !USERMODE(context.sc_cs))
     77 		return (EINVAL);
     78 
     79 	tf->tf_gs = context.sc_gs;
     80 	tf->tf_fs = context.sc_fs;
     81 	tf->tf_es = context.sc_es;
     82 	tf->tf_ds = context.sc_ds;
     83 	tf->tf_eflags &= ~PSL_USER;
     84 	tf->tf_eflags |= context.sc_eflags & PSL_USER;
     85 
     86 	tf->tf_edi = context.sc_edi;
     87 	tf->tf_esi = context.sc_esi;
     88 	tf->tf_ebp = context.sc_ebp;
     89 	tf->tf_ebx = context.sc_ebx;
     90 	tf->tf_edx = context.sc_edx;
     91 	tf->tf_ecx = context.sc_ecx;
     92 	tf->tf_eax = context.sc_eax;
     93 	tf->tf_eip = context.sc_eip;
     94 	tf->tf_cs = context.sc_cs;
     95 	tf->tf_esp = context.sc_esp;
     96 	tf->tf_ss = context.sc_ss;
     97 
     98 	mutex_enter(p->p_lock);
     99 	/* Restore signal stack. */
    100 	if (context.sc_onstack & SS_ONSTACK)
    101 		l->l_sigstk.ss_flags |= SS_ONSTACK;
    102 	else
    103 		l->l_sigstk.ss_flags &= ~SS_ONSTACK;
    104 	/* Restore signal mask. */
    105 	native_sigset13_to_sigset(&context.sc_mask, &mask);
    106 	(void) sigprocmask1(l, SIG_SETMASK, &mask, 0);
    107 	mutex_exit(p->p_lock);
    108 
    109 	return (EJUSTRETURN);
    110 }
    111