/*      $NetBSD: freebsd_syscall.c,v 1.7 2023/10/05 19:41:06 ad Exp $   */

/*-
* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: freebsd_syscall.c,v 1.7 2023/10/05 19:41:06 ad Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/signal.h>
#include <sys/syscall.h>
#include <sys/syscallvar.h>

#include <uvm/uvm_extern.h>

#include <machine/cpu.h>
#include <machine/psl.h>
#include <machine/userret.h>

#include <compat/sys/signal.h>

#include <compat/freebsd/freebsd_machdep.h>
#include <compat/freebsd/freebsd_syscall.h>

void freebsd_syscall(struct trapframe *);

void
freebsd_syscall_intern(struct proc *p)
{

       p->p_md.md_syscall = freebsd_syscall;
}

/*
* syscall(frame):
*      System call request from POSIX system call gate interface to kernel.
* Like trap(), argument is call by reference.
*/
void
freebsd_syscall(struct trapframe *frame)
{
       char *params;
       const struct sysent *callp;
       struct lwp *l;
       struct proc *p;
       int error;
       size_t argsize;
       register_t code, args[8], rval[2];

       l = curlwp;
       p = l->l_proc;

       code = frame->tf_eax;
       callp = p->p_emul->e_sysent;
       params = (char *)frame->tf_esp + sizeof(int);

       switch (code) {
       case SYS_syscall:
               /*
                * Code is first argument, followed by actual args.
                */
               error = ufetch_long((void *)params, (u_long *)&code);
               if (error)
                       goto bad;
               params += sizeof(int);
               break;
       case SYS___syscall:
               /*
                * Like syscall, but code is a quad, so as to maintain
                * quad alignment for the rest of the arguments.
                */
               error = ufetch_long((void *)(params +
                                            _QUAD_LOWWORD * sizeof(int)),
                                   (u_long *)&code);
               if (error)
                       goto bad;
               params += sizeof(quad_t);
               break;
       default:
               break;
       }

       code &= (SYS_NSYSENT - 1);
       callp += code;
       argsize = callp->sy_argsize;
       if (argsize) {
               error = copyin(params, (void *)args, argsize);
               if (error)
                       goto bad;
       }

       if (!__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_entry))
           || (error = trace_enter(code, callp, args)) == 0) {
               rval[0] = 0;
               rval[1] = frame->tf_edx; /* need to keep edx for shared FreeBSD bins */
               error = sy_call(callp, l, args, rval);
       }

       switch (error) {
       case 0:
               frame->tf_eax = rval[0];
               frame->tf_edx = rval[1];
               frame->tf_eflags &= ~PSL_C;     /* carry bit */
               break;
       case ERESTART:
               /*
                * The offset to adjust the PC by depends on whether we entered
                * the kernel through the trap or call gate.  We pushed the
                * size of the instruction into tf_err on entry.
                */
               frame->tf_eip -= frame->tf_err;
               break;
       case EJUSTRETURN:
               /* nothing to do */
               break;
       default:
       bad:
               frame->tf_eax = error;
               frame->tf_eflags |= PSL_C;      /* carry bit */
               break;
       }

       if (__predict_false(p->p_trace_enabled || KDTRACE_ENTRY(callp->sy_return)))
               trace_exit(code, callp, args, rval, error);

       userret(l);
}