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      1 /*	$NetBSD: compat_13_machdep.c,v 1.15 2011/02/08 20:20:16 rmind Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988 University of Utah.
      5  * Copyright (c) 1982, 1986, 1990, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * This code is derived from software contributed to Berkeley by
      9  * the Systems Programming Group of the University of Utah Computer
     10  * Science Department.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  *	from: Utah Hdr: machdep.c 1.74 92/12/20
     37  *	from: @(#)machdep.c	8.10 (Berkeley) 4/20/94
     38  */
     39 
     40 #include <sys/cdefs.h>
     41 __KERNEL_RCSID(0, "$NetBSD: compat_13_machdep.c,v 1.15 2011/02/08 20:20:16 rmind Exp $");
     42 
     43 #include <sys/param.h>
     44 #include <sys/systm.h>
     45 #include <sys/kernel.h>
     46 #include <sys/proc.h>
     47 #include <sys/signal.h>
     48 #include <sys/signalvar.h>
     49 
     50 #include <sys/mount.h>
     51 #include <sys/syscallargs.h>
     52 
     53 #include <compat/sys/signal.h>
     54 #include <compat/sys/signalvar.h>
     55 
     56 #include <machine/cpu.h>
     57 #include <machine/reg.h>
     58 
     59 /*
     60  * System call to cleanup state after a signal
     61  * has been taken.  Reset signal mask and
     62  * stack state from context left by sendsig (above).
     63  * Return to previous pc and psl as specified by
     64  * context left by sendsig. Check carefully to
     65  * make sure that the user has not modified the
     66  * psl to gain improper privileges or to cause
     67  * a machine fault.
     68  */
     69 int
     70 compat_13_sys_sigreturn(struct lwp *l, const struct compat_13_sys_sigreturn_args *uap, register_t *retval)
     71 {
     72 	/* {
     73 		syscallarg(struct sigcontext13 *) sigcntxp;
     74 	} */
     75 	struct proc *p = l->l_proc;
     76 	struct sigcontext13 *scp;
     77 	struct frame *frame;
     78 	struct sigcontext13 tsigc;
     79 	sigset_t mask;
     80 
     81 	/*
     82 	 * The trampoline code hands us the context.
     83 	 * It is unsafe to keep track of it ourselves, in the event that a
     84 	 * program jumps out of a signal handler.
     85 	 */
     86 	scp = SCARG(uap, sigcntxp);
     87 	if ((int)scp & 1)
     88 		return EINVAL;
     89 
     90 	if (copyin(scp, &tsigc, sizeof(tsigc)) != 0)
     91 		return EFAULT;
     92 	scp = &tsigc;
     93 
     94 	/* Make sure the user isn't pulling a fast one on us! */
     95 	if ((scp->sc_ps & (PSL_MBZ|PSL_IPL|PSL_S)) != 0)
     96 		return EINVAL;
     97 
     98 	/* Restore register context. */
     99 	frame = (struct frame *)l->l_md.md_regs;
    100 
    101 	/*
    102 	 * We only support restoring the sigcontext13 in this call.
    103 	 * We are not called from the sigcode (per sendsig()), so
    104 	 * we will not have a sigstate to restore.
    105 	 */
    106 	if (scp->sc_ap != 0)
    107 		return EINVAL;
    108 
    109 	/*
    110 	 * Restore the user supplied information.
    111 	 * This should be at the last so that the error (EINVAL)
    112 	 * is reported to the sigreturn caller, not to the
    113 	 * jump destination.
    114 	 */
    115 
    116 	frame->f_regs[SP] = scp->sc_sp;
    117 	frame->f_regs[A6] = scp->sc_fp;
    118 	frame->f_pc = scp->sc_pc;
    119 	frame->f_sr = scp->sc_ps;
    120 
    121 	mutex_enter(p->p_lock);
    122 
    123 	/* Restore signal stack. */
    124 	if (scp->sc_onstack & SS_ONSTACK)
    125 		l->l_sigstk.ss_flags |= SS_ONSTACK;
    126 	else
    127 		l->l_sigstk.ss_flags &= ~SS_ONSTACK;
    128 
    129 	/* Restore signal mask. */
    130 	native_sigset13_to_sigset(&scp->sc_mask, &mask);
    131 	(void)sigprocmask1(l, SIG_SETMASK, &mask, 0);
    132 
    133 	mutex_exit(p->p_lock);
    134 
    135 	return EJUSTRETURN;
    136 }
    137