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
  20 #include <sys/param.h>
  21 #include <sys/systm.h>
  22 #include <sys/buf.h>
  23 #include <sys/conf.h>
  24 #include <sys/proc.h>
  25 #include <sys/uio.h>
  26 #include <sys/device.h>
  27
  28 #include <vm/vm.h>
  29 #include <vm/vm_extern.h>
  30
  31 static int
  32 physio(cdev_t dev, struct uio *uio, int ioflag)
  33 {
  34         int i;
  35         int error;
  36         int saflags;
  37         size_t iolen;
  38         size_t bcount;
  39         caddr_t ubase;
  40         struct buf *bp;
  41
  42         if (uio->uio_segflg == UIO_USERSPACE)
  43                 bp = getpbuf_mem(NULL);
  44         else
  45                 bp = getpbuf_kva(NULL);
  46         saflags = bp->b_flags;
  47         error = 0;
  48
  49         /* XXX: sanity check */
  50         if (dev->si_iosize_max < PAGE_SIZE) {
  51                 kprintf("WARNING: %s si_iosize_max=%d, using MAXPHYS.\n",
  52                     devtoname(dev), dev->si_iosize_max);
  53                 dev->si_iosize_max = MAXPHYS;
  54         }
  55
  56         /* Must be a real uio */
  57         KKASSERT(uio->uio_segflg != UIO_NOCOPY);
  58
  59         for (i = 0; i < uio->uio_iovcnt; i++) {
  60                 while (uio->uio_iov[i].iov_len) {
  61                         if (uio->uio_rw == UIO_READ)
  62                                 bp->b_cmd = BUF_CMD_READ;
  63                         else
  64                                 bp->b_cmd = BUF_CMD_WRITE;
  65                         bp->b_flags = saflags;
  66                         bcount = uio->uio_iov[i].iov_len;
  67
  68                         reinitbufbio(bp);       /* clear translation cache */
  69                         bp->b_bio1.bio_offset = uio->uio_offset;
  70                         bp->b_bio1.bio_done = biodone_sync;
  71                         bp->b_bio1.bio_flags |= BIO_SYNC;
  72
  73                         /*
  74                          * Setup for mapping the request into kernel memory.
  75                          *
  76                          * We can only write as much as fits in a pbuf,
  77                          * which is MAXPHYS, and no larger then the device's
  78                          * ability.
  79                          *
  80                          * If not using bounce pages the base address of the
  81                          * user mapping into the pbuf may be offset, further
  82                          * reducing how much will actually fit in the pbuf.
  83                          */
  84                         if (bcount > dev->si_iosize_max)
  85                                 bcount = dev->si_iosize_max;
  86
  87                         ubase = uio->uio_iov[i].iov_base;
  88                         iolen = ((vm_offset_t)ubase) & PAGE_MASK;
  89                         if (bcount > bp->b_kvasize)
  90                                 bcount = bp->b_kvasize;
  91
  92                         /*
  93                          * If we have to use a bounce buffer allocate kernel
  94                          * memory and copyin/copyout.  Otherwise map the
  95                          * user buffer directly into kernel memory without
  96                          * copying.
  97                          */
  98                         if (uio->uio_segflg == UIO_USERSPACE) {
  99                                 bp->b_bcount = bcount;
 100                                 if (uio->uio_rw == UIO_WRITE) {
 101                                         error = copyin(ubase, bp->b_data, bcount);
 102                                         if (error)
 103                                                 goto doerror;
 104                                 }
 105                         } else {
 106                                 bp->b_data = uio->uio_iov[i].iov_base;
 107                                 bp->b_bcount = bcount;
 108                         }
 109                         dev_dstrategy(dev, &bp->b_bio1);
 110                         biowait(&bp->b_bio1, "physstr");
 111
 112                         iolen = bp->b_bcount - bp->b_resid;
 113                         if (uio->uio_segflg == UIO_USERSPACE) {
 114                                 if (uio->uio_rw == UIO_READ && iolen) {
 115                                         error = copyout(bp->b_data, ubase, iolen);
 116                                         if (error) {
 117                                                 bp->b_flags |= B_ERROR;
 118                                                 bp->b_error = error;
 119                                         }
 120                                 }
 121                         }
 122                         if (iolen == 0 && !(bp->b_flags & B_ERROR))
 123                                 goto doerror;   /* EOF */
 124                         uio->uio_iov[i].iov_len -= iolen;
 125                         uio->uio_iov[i].iov_base = (char *)uio->uio_iov[i].iov_base + iolen;
 126                         uio->uio_resid -= iolen;
 127                         uio->uio_offset += iolen;
 128                         if (bp->b_flags & B_ERROR) {
 129                                 error = bp->b_error;
 130                                 goto doerror;
 131                         }
 132                 }
 133         }
 134 doerror:
 135         relpbuf(bp, NULL);
 136         return (error);
 137 }
 138
 139 int
 140 physread(struct dev_read_args *ap)
 141 {
 142         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 143 }
 144
 145 int
 146 physwrite(struct dev_write_args *ap)
 147 {
 148         return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
 149 }
 150