kern_physio.c revision 46625 
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 1.32 1999/05/06 20:00:25 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(cdevsw[major(dev)]->d_strategy, NULL, dev, 1, minphys, uio));
39}
40
41int
42physwrite(dev_t dev, struct uio *uio, int ioflag)
43{
44	return(physio(cdevsw[major(dev)]->d_strategy, NULL, dev, 0, minphys, uio));
45}
46
47int
48physio(strategy, bp, dev, rw, minp, uio)
49	d_strategy_t *strategy;
50	struct buf *bp;
51	dev_t dev;
52	int rw;
53	u_int (*minp) __P((struct buf *bp));
54	struct uio *uio;
55{
56	int i;
57	int bufflags = rw?B_READ:0;
58	int error;
59	int spl;
60	caddr_t sa;
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		spl = splbio();
73		while (bp->b_flags & B_BUSY) {
74			bp->b_flags |= B_WANTED;
75			tsleep((caddr_t)bp, PRIBIO, "physbw", 0);
76		}
77		bp->b_flags |= B_BUSY;
78		splx(spl);
79	} else {
80		bp = bpa;
81	}
82
83	/*
84	 * get a copy of the kva from the physical buffer
85	 */
86	sa = bpa->b_data;
87	error = bp->b_error = 0;
88
89	for(i=0;i<uio->uio_iovcnt;i++) {
90		while( uio->uio_iov[i].iov_len) {
91
92			bp->b_dev = dev;
93			bp->b_bcount = uio->uio_iov[i].iov_len;
94			bp->b_flags = B_BUSY | B_PHYS | B_CALL | bufflags;
95			bp->b_iodone = physwakeup;
96			bp->b_data = uio->uio_iov[i].iov_base;
97			bp->b_bcount = minp( bp);
98			if( minp != minphys)
99				bp->b_bcount = minphys( bp);
100			bp->b_bufsize = bp->b_bcount;
101			/*
102			 * pass in the kva from the physical buffer
103			 * for the temporary kernel mapping.
104			 */
105			bp->b_saveaddr = sa;
106			bp->b_blkno = btodb(uio->uio_offset);
107			bp->b_offset = uio->uio_offset;
108
109			if (uio->uio_segflg == UIO_USERSPACE) {
110				if (rw && !useracc(bp->b_data, bp->b_bufsize, B_WRITE)) {
111					error = EFAULT;
112					goto doerror;
113				}
114				if (!rw && !useracc(bp->b_data, bp->b_bufsize, B_READ)) {
115					error = EFAULT;
116					goto doerror;
117				}
118
119				/* bring buffer into kernel space */
120				vmapbuf(bp);
121			}
122
123			/* perform transfer */
124			(*strategy)(bp);
125
126			spl = splbio();
127			while ((bp->b_flags & B_DONE) == 0)
128				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
129			splx(spl);
130
131			/* release mapping into kernel space */
132			if (uio->uio_segflg == UIO_USERSPACE)
133				vunmapbuf(bp);
134
135			/*
136			 * update the uio data
137			 */
138			{
139				int iolen = bp->b_bcount - bp->b_resid;
140
141				if (iolen == 0 && !(bp->b_flags & B_ERROR))
142					goto doerror;	/* EOF */
143				uio->uio_iov[i].iov_len -= iolen;
144				uio->uio_iov[i].iov_base += iolen;
145				uio->uio_resid -= iolen;
146				uio->uio_offset += iolen;
147			}
148
149			/*
150			 * check for an error
151			 */
152			if( bp->b_flags & B_ERROR) {
153				error = bp->b_error;
154				goto doerror;
155			}
156		}
157	}
158
159
160doerror:
161	relpbuf(bpa, NULL);
162	if (!bp_alloc) {
163		bp->b_flags &= ~(B_BUSY|B_PHYS);
164		if( bp->b_flags & B_WANTED) {
165			bp->b_flags &= ~B_WANTED;
166			wakeup((caddr_t)bp);
167		}
168	}
169	/*
170	 * Allow the process UPAGES to be swapped again.
171	 */
172	PRELE(curproc);
173
174	return (error);
175}
176
177u_int
178minphys(bp)
179	struct buf *bp;
180{
181	u_int maxphys = DFLTPHYS;
182	struct cdevsw *bdsw;
183
184	bdsw = cdevsw[major(bp->b_dev)];
185
186	if (bdsw && bdsw->d_maxio) {
187		maxphys = bdsw->d_maxio;
188	}
189	if (bp->b_kvasize && (bp->b_kvasize < maxphys))
190		maxphys = bp->b_kvasize;
191
192	if(((vm_offset_t) bp->b_data) & PAGE_MASK) {
193		maxphys -= PAGE_SIZE;
194	}
195
196	if( bp->b_bcount > maxphys) {
197		bp->b_bcount = maxphys;
198	}
199
200	return bp->b_bcount;
201}
202
203struct buf *
204phygetvpbuf(dev_t dev, int resid)
205{
206	struct cdevsw *bdsw;
207	int maxio;
208
209	bdsw = cdevsw[major(dev)];
210	if ((bdsw == NULL) || (bdsw->d_bmaj == -1))
211		return getpbuf(NULL);
212
213	maxio = bdsw->d_maxio;
214	if (resid > maxio)
215		resid = maxio;
216
217	return getpbuf(NULL);
218}
219
220static void
221physwakeup(bp)
222	struct buf *bp;
223{
224	wakeup((caddr_t) bp);
225	bp->b_flags &= ~B_CALL;
226}
227