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      1 /*	$NetBSD: freebsd_syscall.c,v 1.7 2023/10/05 19:41:06 ad 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 1.7 2023/10/05 19:41:06 ad 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 
     53 void freebsd_syscall(struct trapframe *);
     54 
     55 void
     56 freebsd_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  */
     67 void
     68 freebsd_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 
     81 	code = frame->tf_eax;
     82 	callp = p->p_emul->e_sysent;
     83 	params = (char *)frame->tf_esp + sizeof(int);
     84 
     85 	switch (code) {
     86 	case SYS_syscall:
     87 		/*
     88 		 * Code is first argument, followed by actual args.
     89 		 */
     90 		error = ufetch_long((void *)params, (u_long *)&code);
     91 		if (error)
     92 			goto bad;
     93 		params += sizeof(int);
     94 		break;
     95 	case SYS___syscall:
     96 		/*
     97 		 * Like syscall, but code is a quad, so as to maintain
     98 		 * quad alignment for the rest of the arguments.
     99 		 */
    100 		error = ufetch_long((void *)(params +
    101 					     _QUAD_LOWWORD * sizeof(int)),
    102 				    (u_long *)&code);
    103 		if (error)
    104 			goto bad;
    105 		params += sizeof(quad_t);
    106 		break;
    107 	default:
    108 		break;
    109 	}
    110 
    111 	code &= (SYS_NSYSENT - 1);
    112 	callp += code;
    113 	argsize = callp->sy_argsize;
    114 	if (argsize) {
    115 		error = copyin(params, (void *)args, argsize);
    116 		if (error)
    117 			goto bad;
    118 	}
    119 
    120 	if (!__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_entry))
    121 	    || (error = trace_enter(code, callp, args)) == 0) {
    122 		rval[0] = 0;
    123 		rval[1] = frame->tf_edx; /* need to keep edx for shared FreeBSD bins */
    124 		error = sy_call(callp, l, args, rval);
    125 	}
    126 
    127 	switch (error) {
    128 	case 0:
    129 		frame->tf_eax = rval[0];
    130 		frame->tf_edx = rval[1];
    131 		frame->tf_eflags &= ~PSL_C;	/* carry bit */
    132 		break;
    133 	case ERESTART:
    134 		/*
    135 		 * The offset to adjust the PC by depends on whether we entered
    136 		 * the kernel through the trap or call gate.  We pushed the
    137 		 * size of the instruction into tf_err on entry.
    138 		 */
    139 		frame->tf_eip -= frame->tf_err;
    140 		break;
    141 	case EJUSTRETURN:
    142 		/* nothing to do */
    143 		break;
    144 	default:
    145 	bad:
    146 		frame->tf_eax = error;
    147 		frame->tf_eflags |= PSL_C;	/* carry bit */
    148 		break;
    149 	}
    150 
    151 	if (__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_return)))
    152 		trace_exit(code, callp, args, rval, error);
    153 
    154 	userret(l);
    155 }
    156