1/* $NetBSD$ */
2
3/*-
4 * Copyright (c) 2011 Reinoud Zandijk <reinoud@NetBSD.org>
5 * Copyright (c) 2012 Jared D. McNeill <jmcneill@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, "$NetBSD$");
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 */
47static void
48x86_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 */
98void *
99md_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