sys/kern/kern_physio.c

   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  * $FreeBSD: src/sys/kern/kern_physio.c,v 1.46.2.4 2003/11/14 09:51:47 simokawa Exp $
  20  * $DragonFly: src/sys/kern/kern_physio.c,v 1.25.4.1 2008/09/25 01:44:52 dillon Exp $
  21  */
  22
  23 #include <sys/param.h>
  24 #include <sys/systm.h>
  25 #include <sys/buf.h>
  26 #include <sys/conf.h>
  27 #include <sys/proc.h>
  28 #include <sys/uio.h>
  29 #include <sys/device.h>
  30 #include <sys/thread2.h>
  31
  32 #include <vm/vm.h>
  33 #include <vm/vm_extern.h>
  34
  35 static void
  36 physwakeup(struct bio *bio)
  37 {
  38         bio->bio_buf->b_cmd = BUF_CMD_DONE;
  39         wakeup(bio);
  40 }
  41
  42 static int
  43 physio(cdev_t dev, struct uio *uio, int ioflag)
  44 {
  45         int i;
  46         int error;
  47         int saflags;
  48         int iolen;
  49         int bcount;
  50         int bounceit;
  51         caddr_t ubase;
  52         struct buf *bp;
  53
  54         bp = getpbuf(NULL);
  55         saflags = bp->b_flags;
  56         error = 0;
  57
  58         /* XXX: sanity check */
  59         if (dev->si_iosize_max < PAGE_SIZE) {
  60                 kprintf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  61                     devtoname(dev), dev->si_iosize_max);
  62                 dev->si_iosize_max = DFLTPHYS;
  63         }
  64
  65         /* Must be a real uio */
  66         KKASSERT(uio->uio_segflg != UIO_NOCOPY);
  67
  68         for (i = 0; i < uio->uio_iovcnt; i++) {
  69                 while (uio->uio_iov[i].iov_len) {
  70                         if (uio->uio_rw == UIO_READ)
  71                                 bp->b_cmd = BUF_CMD_READ;
  72                         else
  73                                 bp->b_cmd = BUF_CMD_WRITE;
  74                         bp->b_flags = saflags;
  75                         bcount = uio->uio_iov[i].iov_len;
  76
  77                         reinitbufbio(bp);       /* clear translation cache */
  78                         bp->b_bio1.bio_offset = uio->uio_offset;
  79                         bp->b_bio1.bio_done = physwakeup;
  80
  81                         /*
  82                          * Setup for mapping the request into kernel memory.
  83                          *
  84                          * We can only write as much as fits in a pbuf,
  85                          * which is MAXPHYS, and no larger then the device's
  86                          * ability.
  87                          *
  88                          * If not using bounce pages the base address of the
  89                          * user mapping into the pbuf may be offset, further
  90                          * reducing how much will actually fit in the pbuf.
  91                          */
  92                         if (bcount > dev->si_iosize_max)
  93                                 bcount = dev->si_iosize_max;
  94
  95                         ubase = uio->uio_iov[i].iov_base;
  96                         bounceit = (int)(((vm_offset_t)ubase) & 15);
  97                         iolen = ((vm_offset_t)ubase) & PAGE_MASK;
  98                         if (bounceit) {
  99                                 if (bcount > bp->b_kvasize)
 100                                         bcount = bp->b_kvasize;
 101                         } else {
 102                                 if ((bcount + iolen) > bp->b_kvasize) {
 103                                         bcount = bp->b_kvasize;
 104                                         if (iolen != 0)
 105                                                 bcount -= PAGE_SIZE;
 106                                 }
 107                         }
 108
 109                         /*
 110                          * If we have to use a bounce buffer allocate kernel
 111                          * memory and copyin/copyout.  Otherwise map the
 112                          * user buffer directly into kernel memory without
 113                          * copying.
 114                          */
 115                         if (uio->uio_segflg == UIO_USERSPACE) {
 116                                 if (bounceit) {
 117                                         bp->b_data = bp->b_kvabase;
 118                                         bp->b_bcount = bcount;
 119                                         vm_hold_load_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 120                                         if (uio->uio_rw == UIO_WRITE) {
 121                                                 error = copyin(ubase, bp->b_data, bcount);
 122                                                 if (error) {
 123                                                         vm_hold_free_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 124                                                         goto doerror;
 125                                                 }
 126                                         }
 127                                 } else if (vmapbuf(bp, ubase, bcount) < 0) {
 128                                         error = EFAULT;
 129                                         goto doerror;
 130                                 }
 131                         } else {
 132                                 bp->b_data = uio->uio_iov[i].iov_base;
 133                                 bp->b_bcount = bcount;
 134                         }
 135                         dev_dstrategy(dev, &bp->b_bio1);
 136                         crit_enter();
 137                         while (bp->b_cmd != BUF_CMD_DONE)
 138                                 tsleep(&bp->b_bio1, 0, "physstr", 0);
 139                         crit_exit();
 140
 141                         iolen = bp->b_bcount - bp->b_resid;
 142                         if (uio->uio_segflg == UIO_USERSPACE) {
 143                                 if (bounceit) {
 144                                         if (uio->uio_rw == UIO_READ && iolen) {
 145                                                 error = copyout(bp->b_data, ubase, iolen);
 146                                                 if (error) {
 147                                                         bp->b_flags |= B_ERROR;
 148                                                         bp->b_error = error;
 149                                                 }
 150                                         }
 151                                         vm_hold_free_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 152                                 } else {
 153                                         vunmapbuf(bp);
 154                                 }
 155                         }
 156                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 157                                 goto doerror;   /* EOF */
 158                         uio->uio_iov[i].iov_len -= iolen;
 159                         uio->uio_iov[i].iov_base += iolen;
 160                         uio->uio_resid -= iolen;
 161                         uio->uio_offset += iolen;
 162                         if (bp->b_flags & B_ERROR) {
 163                                 error = bp->b_error;
 164                                 goto doerror;
 165                         }
 166                 }
 167         }
 168 doerror:
 169         relpbuf(bp, NULL);
 170         return (error);
 171 }
 172
 173 int
 174 physread(struct dev_read_args *ap)
 175 {
 176         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 177 }
 178
 179 int
 180 physwrite(struct dev_write_args *ap)
 181 {
 182         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 183 }
 184