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      1 /* $NetBSD: syscallemu_x86.c,v 1.1 2012/01/06 13:16:20 jmcneill Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2011 Reinoud Zandijk <reinoud (at) NetBSD.org>
      5  * Copyright (c) 2012 Jared D. McNeill <jmcneill (at) invisible.ca>
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27  * POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include <sys/cdefs.h>
     31 __KERNEL_RCSID(0, "$NetBSD: syscallemu_x86.c,v 1.1 2012/01/06 13:16:20 jmcneill Exp $");
     32 
     33 #include <sys/param.h>
     34 #include <sys/proc.h>
     35 #include <sys/systm.h>
     36 
     37 #include <machine/userret.h>
     38 
     39 #include "syscallemu.h"
     40 
     41 /*
     42  * If syscallemu specific data is present for the process, verify that the
     43  * caller is allowed to execute system calls. If not, deliver a SIGILL to
     44  * the process. When syscallemu specific data is not present, simply defer
     45  * to the original syscall handler.
     46  */
     47 static void
     48 x86_syscall_emu(struct trapframe *frame)
     49 {
     50 	void (*md_syscall)(struct trapframe *) = NULL;
     51 	struct syscallemu_data *sce;
     52 	register_t rip_call;
     53 	struct proc *p;
     54 	ksiginfo_t ksi;
     55 	lwp_t *l;
     56 
     57 	l = curlwp;
     58 	p = l->l_proc;
     59 
     60 	rip_call = X86_TF_RIP(frame) - frame->tf_err;
     61 
     62 	/* Determine if we need to emulate the system call */
     63 	sce = syscallemu_getsce(p);
     64 	if (sce) {
     65 		if ((rip_call >= sce->sce_user_start &&
     66 		     rip_call < sce->sce_user_end) ||
     67 		    (rip_call + frame->tf_err >= sce->sce_user_start &&
     68 		     rip_call + frame->tf_err < sce->sce_user_end)) {
     69 			md_syscall = NULL;
     70 		} else {
     71 			md_syscall = sce->sce_md_syscall;
     72 		}
     73 	} else {
     74 		md_syscall = p->p_md.md_syscall;
     75 	}
     76 
     77 	if (md_syscall == NULL) {
     78 		/* If emulating, deliver SIGILL to process */
     79 		X86_TF_RIP(frame) = rip_call;
     80 		KSI_INIT_TRAP(&ksi);
     81 		ksi.ksi_signo = SIGILL;
     82 		ksi.ksi_code = ILL_ILLTRP;
     83 		ksi.ksi_addr = (void *)X86_TF_RIP(frame);
     84 		ksi.ksi_trap = 0;
     85 		trapsignal(l, &ksi);
     86 		userret(l);
     87 	} else {
     88 		/* Not emulating, so treat as a normal syscall */
     89 		KASSERT(md_syscall != NULL);
     90 		md_syscall(frame);
     91 	}
     92 }
     93 
     94 /*
     95  * Set p_md.md_syscall to our syscall filter, and return a pointer to the
     96  * original syscall handler.
     97  */
     98 void *
     99 md_syscallemu(struct proc *p)
    100 {
    101 	void *osyscall;
    102 
    103 	osyscall = p->p_md.md_syscall;
    104 	p->p_md.md_syscall = x86_syscall_emu;
    105 
    106 	return osyscall;
    107 }
    108