freebsd_syscall.c revision 1.2 
1/*	$NetBSD: freebsd_syscall.c,v 1.2 2017/08/08 08:04:06 maxv Exp $	*/
2
3/*-
4 * Copyright (c) 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: freebsd_syscall.c,v 1.2 2017/08/08 08:04:06 maxv Exp $");
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/proc.h>
38#include <sys/signal.h>
39#include <sys/syscall.h>
40#include <sys/syscallvar.h>
41
42#include <uvm/uvm_extern.h>
43
44#include <machine/cpu.h>
45#include <machine/psl.h>
46#include <machine/userret.h>
47
48#include <compat/sys/signal.h>
49
50#include <compat/freebsd/freebsd_machdep.h>
51#include <compat/freebsd/freebsd_syscall.h>
52
53void freebsd_syscall(struct trapframe *);
54
55void
56freebsd_syscall_intern(struct proc *p)
57{
58
59	p->p_md.md_syscall = freebsd_syscall;
60}
61
62/*
63 * syscall(frame):
64 *	System call request from POSIX system call gate interface to kernel.
65 * Like trap(), argument is call by reference.
66 */
67void
68freebsd_syscall(struct trapframe *frame)
69{
70	char *params;
71	const struct sysent *callp;
72	struct lwp *l;
73	struct proc *p;
74	int error;
75	size_t argsize;
76	register_t code, args[8], rval[2];
77
78	l = curlwp;
79	p = l->l_proc;
80	LWP_CACHE_CREDS(l, p);
81
82	code = frame->tf_eax;
83	callp = p->p_emul->e_sysent;
84	params = (char *)frame->tf_esp + sizeof(int);
85
86	switch (code) {
87	case SYS_syscall:
88		/*
89		 * Code is first argument, followed by actual args.
90		 */
91		code = fuword(params);
92		params += sizeof(int);
93		break;
94	case SYS___syscall:
95		/*
96		 * Like syscall, but code is a quad, so as to maintain
97		 * quad alignment for the rest of the arguments.
98		 */
99		code = fuword(params + _QUAD_LOWWORD * sizeof(int));
100		params += sizeof(quad_t);
101		break;
102	default:
103		break;
104	}
105
106	code &= (SYS_NSYSENT - 1);
107	callp += code;
108	argsize = callp->sy_argsize;
109	if (argsize) {
110		error = copyin(params, (void *)args, argsize);
111		if (error)
112			goto bad;
113	}
114
115	if (!__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_entry))
116	    || (error = trace_enter(code, callp, args)) == 0) {
117		rval[0] = 0;
118		rval[1] = frame->tf_edx; /* need to keep edx for shared FreeBSD bins */
119		error = sy_call(callp, l, args, rval);
120	}
121
122	switch (error) {
123	case 0:
124		frame->tf_eax = rval[0];
125		frame->tf_edx = rval[1];
126		frame->tf_eflags &= ~PSL_C;	/* carry bit */
127		break;
128	case ERESTART:
129		/*
130		 * The offset to adjust the PC by depends on whether we entered
131		 * the kernel through the trap or call gate.  We pushed the
132		 * size of the instruction into tf_err on entry.
133		 */
134		frame->tf_eip -= frame->tf_err;
135		break;
136	case EJUSTRETURN:
137		/* nothing to do */
138		break;
139	default:
140	bad:
141		frame->tf_eax = error;
142		frame->tf_eflags |= PSL_C;	/* carry bit */
143		break;
144	}
145
146	if (__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_return)))
147		trace_exit(code, callp, args, rval, error);
148
149	userret(l);
150}
151