kern_physio.c revision 49771 
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 1.35 1999/06/26 02:46:02 mckusick 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	int bp_alloc = (bp == 0);
61	struct buf *bpa;
62
63	/*
64	 * Keep the process UPAGES from being swapped. (XXX for performance?)
65	 */
66	PHOLD(curproc);
67
68	/* create and build a buffer header for a transfer */
69	bpa = (struct buf *)phygetvpbuf(dev, uio->uio_resid);
70	if (!bp_alloc)
71		BUF_LOCK(bp, LK_EXCLUSIVE);
72	else
73		bp = bpa;
74
75	/*
76	 * get a copy of the kva from the physical buffer
77	 */
78	sa = bpa->b_data;
79	error = bp->b_error = 0;
80
81	for (i = 0; i < uio->uio_iovcnt; i++) {
82		while (uio->uio_iov[i].iov_len) {
83
84			bp->b_dev = dev;
85			bp->b_bcount = uio->uio_iov[i].iov_len;
86			bp->b_flags = B_PHYS | B_CALL | bufflags;
87			bp->b_iodone = physwakeup;
88			bp->b_data = uio->uio_iov[i].iov_base;
89			bp->b_bcount = minp( bp);
90			if( minp != minphys)
91				bp->b_bcount = minphys( bp);
92			bp->b_bufsize = bp->b_bcount;
93			/*
94			 * pass in the kva from the physical buffer
95			 * for the temporary kernel mapping.
96			 */
97			bp->b_saveaddr = sa;
98			bp->b_blkno = btodb(uio->uio_offset);
99			bp->b_offset = uio->uio_offset;
100
101			if (uio->uio_segflg == UIO_USERSPACE) {
102				if (rw && !useracc(bp->b_data, bp->b_bufsize, B_WRITE)) {
103					error = EFAULT;
104					goto doerror;
105				}
106				if (!rw && !useracc(bp->b_data, bp->b_bufsize, B_READ)) {
107					error = EFAULT;
108					goto doerror;
109				}
110
111				/* bring buffer into kernel space */
112				vmapbuf(bp);
113			}
114
115			/* perform transfer */
116			BUF_STRATEGY(bp, 0);
117
118			spl = splbio();
119			while ((bp->b_flags & B_DONE) == 0)
120				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
121			splx(spl);
122
123			/* release mapping into kernel space */
124			if (uio->uio_segflg == UIO_USERSPACE)
125				vunmapbuf(bp);
126
127			/*
128			 * update the uio data
129			 */
130			{
131				int iolen = bp->b_bcount - bp->b_resid;
132
133				if (iolen == 0 && !(bp->b_flags & B_ERROR))
134					goto doerror;	/* EOF */
135				uio->uio_iov[i].iov_len -= iolen;
136				uio->uio_iov[i].iov_base += iolen;
137				uio->uio_resid -= iolen;
138				uio->uio_offset += iolen;
139			}
140
141			/*
142			 * check for an error
143			 */
144			if( bp->b_flags & B_ERROR) {
145				error = bp->b_error;
146				goto doerror;
147			}
148		}
149	}
150
151
152doerror:
153	relpbuf(bpa, NULL);
154	if (!bp_alloc) {
155		bp->b_flags &= ~B_PHYS;
156		BUF_UNLOCK(bp);
157	}
158	/*
159	 * Allow the process UPAGES to be swapped again.
160	 */
161	PRELE(curproc);
162
163	return (error);
164}
165
166u_int
167minphys(bp)
168	struct buf *bp;
169{
170	u_int maxphys = DFLTPHYS;
171	struct cdevsw *bdsw;
172
173	bdsw = devsw(bp->b_dev);
174
175	if (bdsw && bdsw->d_maxio) {
176		maxphys = bdsw->d_maxio;
177	}
178	if (bp->b_kvasize && (bp->b_kvasize < maxphys))
179		maxphys = bp->b_kvasize;
180
181	if(((vm_offset_t) bp->b_data) & PAGE_MASK) {
182		maxphys -= PAGE_SIZE;
183	}
184
185	if( bp->b_bcount > maxphys) {
186		bp->b_bcount = maxphys;
187	}
188
189	return bp->b_bcount;
190}
191
192struct buf *
193phygetvpbuf(dev_t dev, int resid)
194{
195	struct cdevsw *bdsw;
196	int maxio;
197
198	bdsw = devsw(dev);
199	if ((bdsw == NULL) || (bdsw->d_bmaj == -1))
200		return getpbuf(NULL);
201
202	maxio = bdsw->d_maxio;
203	if (resid > maxio)
204		resid = maxio;
205
206	return getpbuf(NULL);
207}
208
209static void
210physwakeup(bp)
211	struct buf *bp;
212{
213	wakeup((caddr_t) bp);
214	bp->b_flags &= ~B_CALL;
215}
216