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 1.27 2008/08/22 08:47:56 swildner 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 int
  36 physio(cdev_t dev, struct uio *uio, int ioflag)
  37 {
  38         int i;
  39         int error;
  40         int saflags;
  41         int iolen;
  42         int bcount;
  43         int bounceit;
  44         caddr_t ubase;
  45         struct buf *bp;
  46
  47         bp = getpbuf(NULL);
  48         saflags = bp->b_flags;
  49         error = 0;
  50
  51         /* XXX: sanity check */
  52         if (dev->si_iosize_max < PAGE_SIZE) {
  53                 kprintf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
  54                     devtoname(dev), dev->si_iosize_max);
  55                 dev->si_iosize_max = DFLTPHYS;
  56         }
  57
  58         /* Must be a real uio */
  59         KKASSERT(uio->uio_segflg != UIO_NOCOPY);
  60
  61         for (i = 0; i < uio->uio_iovcnt; i++) {
  62                 while (uio->uio_iov[i].iov_len) {
  63                         if (uio->uio_rw == UIO_READ)
  64                                 bp->b_cmd = BUF_CMD_READ;
  65                         else
  66                                 bp->b_cmd = BUF_CMD_WRITE;
  67                         bp->b_flags = saflags;
  68                         bcount = uio->uio_iov[i].iov_len;
  69
  70                         reinitbufbio(bp);       /* clear translation cache */
  71                         bp->b_bio1.bio_offset = uio->uio_offset;
  72                         bp->b_bio1.bio_done = biodone_sync;
  73                         bp->b_bio1.bio_flags |= BIO_SYNC;
  74
  75                         /*
  76                          * Setup for mapping the request into kernel memory.
  77                          *
  78                          * We can only write as much as fits in a pbuf,
  79                          * which is MAXPHYS, and no larger then the device's
  80                          * ability.
  81                          *
  82                          * If not using bounce pages the base address of the
  83                          * user mapping into the pbuf may be offset, further
  84                          * reducing how much will actually fit in the pbuf.
  85                          */
  86                         if (bcount > dev->si_iosize_max)
  87                                 bcount = dev->si_iosize_max;
  88
  89                         ubase = uio->uio_iov[i].iov_base;
  90                         bounceit = (int)(((vm_offset_t)ubase) & 15);
  91                         iolen = ((vm_offset_t)ubase) & PAGE_MASK;
  92                         if (bounceit) {
  93                                 if (bcount > bp->b_kvasize)
  94                                         bcount = bp->b_kvasize;
  95                         } else {
  96                                 if ((bcount + iolen) > bp->b_kvasize) {
  97                                         bcount = bp->b_kvasize;
  98                                         if (iolen != 0)
  99                                                 bcount -= PAGE_SIZE;
 100                                 }
 101                         }
 102
 103                         /*
 104                          * If we have to use a bounce buffer allocate kernel
 105                          * memory and copyin/copyout.  Otherwise map the
 106                          * user buffer directly into kernel memory without
 107                          * copying.
 108                          */
 109                         if (uio->uio_segflg == UIO_USERSPACE) {
 110                                 if (bounceit) {
 111                                         bp->b_data = bp->b_kvabase;
 112                                         bp->b_bcount = bcount;
 113                                         vm_hold_load_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 114                                         if (uio->uio_rw == UIO_WRITE) {
 115                                                 error = copyin(ubase, bp->b_data, bcount);
 116                                                 if (error) {
 117                                                         vm_hold_free_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 118                                                         goto doerror;
 119                                                 }
 120                                         }
 121                                 } else if (vmapbuf(bp, ubase, bcount) < 0) {
 122                                         error = EFAULT;
 123                                         goto doerror;
 124                                 }
 125                         } else {
 126                                 bp->b_data = uio->uio_iov[i].iov_base;
 127                                 bp->b_bcount = bcount;
 128                         }
 129                         dev_dstrategy(dev, &bp->b_bio1);
 130                         biowait(&bp->b_bio1, "physstr");
 131
 132                         iolen = bp->b_bcount - bp->b_resid;
 133                         if (uio->uio_segflg == UIO_USERSPACE) {
 134                                 if (bounceit) {
 135                                         if (uio->uio_rw == UIO_READ && iolen) {
 136                                                 error = copyout(bp->b_data, ubase, iolen);
 137                                                 if (error) {
 138                                                         bp->b_flags |= B_ERROR;
 139                                                         bp->b_error = error;
 140                                                 }
 141                                         }
 142                                         vm_hold_free_pages(bp, (vm_offset_t)bp->b_data, (vm_offset_t)bp->b_data + bcount);
 143                                 } else {
 144                                         vunmapbuf(bp);
 145                                 }
 146                         }
 147                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 148                                 goto doerror;   /* EOF */
 149                         uio->uio_iov[i].iov_len -= iolen;
 150                         uio->uio_iov[i].iov_base = (char *)uio->uio_iov[i].iov_base + iolen;
 151                         uio->uio_resid -= iolen;
 152                         uio->uio_offset += iolen;
 153                         if (bp->b_flags & B_ERROR) {
 154                                 error = bp->b_error;
 155                                 goto doerror;
 156                         }
 157                 }
 158         }
 159 doerror:
 160         relpbuf(bp, NULL);
 161         return (error);
 162 }
 163
 164 int
 165 physread(struct dev_read_args *ap)
 166 {
 167         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 168 }
 169
 170 int
 171 physwrite(struct dev_write_args *ap)
 172 {
 173         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 174 }
 175