kern_physio.c revision 50108 
1/*
2 * Copyright (c) 1994 John S. Dyson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice immediately at the beginning of the file, without modification,
10 *    this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Absolutely no warranty of function or purpose is made by the author
15 *    John S. Dyson.
16 * 4. Modifications may be freely made to this file if the above conditions
17 *    are met.
18 *
19 * $Id: kern_physio.c,v 1.36 1999/08/14 11:40:42 phk Exp $
20 */
21
22#include <sys/param.h>
23#include <sys/systm.h>
24#include <sys/buf.h>
25#include <sys/conf.h>
26#include <sys/proc.h>
27#include <sys/uio.h>
28
29#include <vm/vm.h>
30#include <vm/vm_extern.h>
31
32static void	physwakeup __P((struct buf *bp));
33static struct buf * phygetvpbuf(dev_t dev, int resid);
34
35int
36physread(dev_t dev, struct uio *uio, int ioflag)
37{
38	return(physio(NULL, dev, 1, minphys, uio));
39}
40
41int
42physwrite(dev_t dev, struct uio *uio, int ioflag)
43{
44	return(physio(NULL, dev, 0, minphys, uio));
45}
46
47int
48physio(bp, dev, rw, minp, uio)
49	struct buf *bp;
50	dev_t dev;
51	int rw;
52	u_int (*minp) __P((struct buf *bp));
53	struct uio *uio;
54{
55	int i;
56	int bufflags = rw?B_READ:0;
57	int error;
58	int spl;
59	caddr_t sa;
60	off_t blockno;
61	int bp_alloc = (bp == 0);
62	struct buf *bpa;
63
64	/*
65	 * Keep the process UPAGES from being swapped. (XXX for performance?)
66	 */
67	PHOLD(curproc);
68
69	/* create and build a buffer header for a transfer */
70	bpa = (struct buf *)phygetvpbuf(dev, uio->uio_resid);
71	if (!bp_alloc)
72		BUF_LOCK(bp, LK_EXCLUSIVE);
73	else
74		bp = bpa;
75
76	/*
77	 * get a copy of the kva from the physical buffer
78	 */
79	sa = bpa->b_data;
80	error = bp->b_error = 0;
81
82	for (i = 0; i < uio->uio_iovcnt; i++) {
83		while (uio->uio_iov[i].iov_len) {
84
85			bp->b_dev = dev;
86			bp->b_bcount = uio->uio_iov[i].iov_len;
87			bp->b_flags = B_PHYS | B_CALL | bufflags;
88			bp->b_iodone = physwakeup;
89			bp->b_data = uio->uio_iov[i].iov_base;
90			bp->b_bcount = minp( bp);
91			if( minp != minphys)
92				bp->b_bcount = minphys( bp);
93			bp->b_bufsize = bp->b_bcount;
94			/*
95			 * pass in the kva from the physical buffer
96			 * for the temporary kernel mapping.
97			 */
98			bp->b_saveaddr = sa;
99			blockno = uio->uio_offset >> DEV_BSHIFT;
100			bp->b_blkno = blockno;
101			if (bp->b_blkno != blockno) {
102				error = EINVAL;
103				goto doerror;
104			}
105			bp->b_offset = uio->uio_offset;
106
107			if (uio->uio_segflg == UIO_USERSPACE) {
108				if (rw && !useracc(bp->b_data, bp->b_bufsize, B_WRITE)) {
109					error = EFAULT;
110					goto doerror;
111				}
112				if (!rw && !useracc(bp->b_data, bp->b_bufsize, B_READ)) {
113					error = EFAULT;
114					goto doerror;
115				}
116
117				/* bring buffer into kernel space */
118				vmapbuf(bp);
119			}
120
121			/* perform transfer */
122			BUF_STRATEGY(bp, 0);
123
124			spl = splbio();
125			while ((bp->b_flags & B_DONE) == 0)
126				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
127			splx(spl);
128
129			/* release mapping into kernel space */
130			if (uio->uio_segflg == UIO_USERSPACE)
131				vunmapbuf(bp);
132
133			/*
134			 * update the uio data
135			 */
136			{
137				int iolen = bp->b_bcount - bp->b_resid;
138
139				if (iolen == 0 && !(bp->b_flags & B_ERROR))
140					goto doerror;	/* EOF */
141				uio->uio_iov[i].iov_len -= iolen;
142				uio->uio_iov[i].iov_base += iolen;
143				uio->uio_resid -= iolen;
144				uio->uio_offset += iolen;
145			}
146
147			/*
148			 * check for an error
149			 */
150			if( bp->b_flags & B_ERROR) {
151				error = bp->b_error;
152				goto doerror;
153			}
154		}
155	}
156
157
158doerror:
159	relpbuf(bpa, NULL);
160	if (!bp_alloc) {
161		bp->b_flags &= ~B_PHYS;
162		BUF_UNLOCK(bp);
163	}
164	/*
165	 * Allow the process UPAGES to be swapped again.
166	 */
167	PRELE(curproc);
168
169	return (error);
170}
171
172u_int
173minphys(bp)
174	struct buf *bp;
175{
176	u_int maxphys = DFLTPHYS;
177	struct cdevsw *bdsw;
178
179	bdsw = devsw(bp->b_dev);
180
181	if (bdsw && bdsw->d_maxio) {
182		maxphys = bdsw->d_maxio;
183	}
184	if (bp->b_kvasize && (bp->b_kvasize < maxphys))
185		maxphys = bp->b_kvasize;
186
187	if(((vm_offset_t) bp->b_data) & PAGE_MASK) {
188		maxphys -= PAGE_SIZE;
189	}
190
191	if( bp->b_bcount > maxphys) {
192		bp->b_bcount = maxphys;
193	}
194
195	return bp->b_bcount;
196}
197
198struct buf *
199phygetvpbuf(dev_t dev, int resid)
200{
201	struct cdevsw *bdsw;
202	int maxio;
203
204	bdsw = devsw(dev);
205	if ((bdsw == NULL) || (bdsw->d_bmaj == -1))
206		return getpbuf(NULL);
207
208	maxio = bdsw->d_maxio;
209	if (resid > maxio)
210		resid = maxio;
211
212	return getpbuf(NULL);
213}
214
215static void
216physwakeup(bp)
217	struct buf *bp;
218{
219	wakeup((caddr_t) bp);
220	bp->b_flags &= ~B_CALL;
221}
222