text: /*	$OpenBSD: mem.c,v 1.1 2010/12/31 21:38:08 miod Exp $ */
  
  /*
   * Copyright (c) 1988 University of Utah.
   * Copyright (c) 1982, 1986, 1990, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * the Systems Programming Group of the University of Utah Computer
   * Science Department.
   *
   * 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.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
   *
   *	@(#)mem.c	8.3 (Berkeley) 1/12/94
   */
  
  /*
   * Memory special file
   */
  
  #include <sys/param.h>
  #include <sys/buf.h>
  #include <sys/systm.h>
  #include <sys/uio.h>
  #include <sys/malloc.h>
  
  #include <machine/conf.h>
  
  #include <uvm/uvm_extern.h>
  
  caddr_t zpage;
  extern vaddr_t first_addr, last_addr;
  extern caddr_t kernelstart;
  extern void *etext;
  
  /*ARGSUSED*/
  int
  mmopen(dev, flag, mode, p)
  	dev_t dev;
  	int flag, mode;
  	struct proc *p;
  {
  
  	switch (minor(dev)) {
  		case 0:
  		case 1:
  		case 2:
  		case 12:
  			return (0);
  		default:
  			return (ENXIO);
  	}
  }
  
  /*ARGSUSED*/
  int
  mmclose(dev, flag, mode, p)
  	dev_t dev;
  	int flag, mode;
  	struct proc *p;
  {
  
  	return (0);
  }
  
  /*ARGSUSED*/
  int
  mmrw(dev, uio, flags)
  	dev_t dev;
  	struct uio *uio;
  	int flags;
  {
  	vaddr_t v;
  	int c;
  	struct iovec *iov;
  	int error = 0;
  
  	while (uio->uio_resid > 0 && error == 0) {
  		iov = uio->uio_iov;
  		if (iov->iov_len == 0) {
  			uio->uio_iov++;
  			uio->uio_iovcnt--;
  			if (uio->uio_iovcnt < 0)
  				panic("mmrw");
  			continue;
  		}
  		switch (minor(dev)) {
  
  /* minor device 0 is physical memory */
  		case 0:
  			v = uio->uio_offset;
  			error = uiomove((caddr_t)v, uio->uio_resid, uio);
  			continue;
  
  /* minor device 1 is kernel memory */
  		case 1:
  			v = uio->uio_offset;
  			c = min(iov->iov_len, MAXPHYS);
  			if (v >= (vaddr_t)&kernelstart &&
  			    v < (vaddr_t)first_addr) {
  				if (v < (vaddr_t)etext &&
  				    uio->uio_rw == UIO_WRITE)
  					return (EFAULT);
  			} else if (!uvm_kernacc((caddr_t)v, c,
  			    uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
  				return (EFAULT);
  			error = uiomove((caddr_t)v, c, uio);
  			continue;
  
  /* minor device 2 is EOF/RATHOLE */
  		case 2:
  			if (uio->uio_rw == UIO_WRITE)
  				uio->uio_resid = 0;
  			return (0);
  
  /* minor device 12 (/dev/zero) is source of nulls on read, rathole on write */
  		case 12:
  			if (uio->uio_rw == UIO_WRITE) {
  				c = iov->iov_len;
  				break;
  			}
  			if (zpage == NULL)
  				zpage = malloc(PAGE_SIZE, M_TEMP,
  				    M_WAITOK | M_ZERO);
  			c = min(iov->iov_len, PAGE_SIZE);
  			error = uiomove(zpage, c, uio);
  			continue;
  
  		default:
  			return (ENXIO);
  		}
  		if (error)
  			break;
  		iov->iov_base += c;
  		iov->iov_len -= c;
  		uio->uio_offset += c;
  		uio->uio_resid -= c;
  	}
  
  	return (error);
  }
  
  paddr_t
  mmmmap(dev, off, prot)
          dev_t dev;
          off_t off;
  	int prot;
  {
  	return (-1);
  }
  
  /*ARGSUSED*/
  int
  mmioctl(dev, cmd, data, flags, p)
  	dev_t dev;
  	u_long cmd;
  	caddr_t data;
  	int flags;
  	struct proc *p;
  {
  	return (EOPNOTSUPP);
  }
  