fix includes; speed up writes to /dev/null

[unix-history] / usr / src / sys / hp300 / hp300 / mem.c

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990 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.
 *
 * %sccs.include.redist.c%
 *
 * from: Utah $Hdr: mem.c 1.13 89/10/08$
 *
 *	@(#)mem.c	7.4 (Berkeley) %G%
 */

/*
 * Memory special file
 */

#include "param.h"
#include "conf.h"
#include "buf.h"
#include "systm.h"
#include "malloc.h"

#include "../include/cpu.h"

#include "vm/vm_param.h"
#include "vm/lock.h"
#include "vm/vm_statistics.h"
#include "vm/pmap.h"
#include "vm/vm_prot.h"

/*ARGSUSED*/
mmrw(dev, uio, flags)
	dev_t dev;
	struct uio *uio;
	int flags;
{
	register int o;
	register u_int c, v;
	register struct iovec *iov;
	int error = 0;
	caddr_t zbuf = NULL;
	extern u_int lowram;

	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;
#ifndef DEBUG
			/* allow reads only in RAM (except for DEBUG) */
			if (v >= 0xFFFFFFFC || v < lowram)
				return (EFAULT);
#endif
			pmap_enter(pmap_kernel(), vmmap, v,
				uio->uio_rw == UIO_READ ? VM_PROT_READ : VM_PROT_WRITE,
				TRUE);
			o = (int)uio->uio_offset & PGOFSET;
			c = (u_int)(NBPG - ((int)iov->iov_base & PGOFSET));
			c = MIN(c, (u_int)(NBPG - o));
			c = MIN(c, (u_int)iov->iov_len);
			error = uiomove((caddr_t)&vmmap[o], (int)c, uio);
			pmap_remove(pmap_kernel(), vmmap, &vmmap[NBPG]);
			continue;

/* minor device 1 is kernel memory */
		case 1:
			c = MIN(iov->iov_len, MAXPHYS);
			if (!kernacc((caddr_t)uio->uio_offset, c,
			    uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
				return (EFAULT);
			error = uiomove((caddr_t)uio->uio_offset, (int)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 (zbuf == NULL) {
				zbuf = (caddr_t)
				    malloc(CLBYTES, M_TEMP, M_WAITOK);
				bzero(zbuf, CLBYTES);
			}
			c = MIN(iov->iov_len, CLBYTES);
			error = uiomove(zbuf, (int)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;
	}
	if (zbuf)
		free(zbuf, M_TEMP);
	return (error);
}