sys/kern/kern_xio.c

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_xio.c,v 1.9 2005/03/02 18:42:08 hmp Exp $
  35  */
  36 /*
  37  * Kernel XIO interface.  An initialized XIO is basically a collection of
  38  * appropriately held vm_page_t's.  XIO buffers are vmspace agnostic and
  39  * can represent userspace or kernelspace buffers, and can be passed to
  40  * foreign threads outside of the originating vmspace.  XIO buffers are
  41  * not mapped into KVM and thus can be manipulated and passed around with
  42  * very low overheads.
  43  *
  44  * The intent is for XIO to be used in the I/O path, VFS, CAPS, and other
  45  * places that need to pass (possibly userspace) data between threads.
  46  *
  47  * TODO: check for busy page when modifying, check writeable.
  48  */
  49
  50 #include <sys/param.h>
  51 #include <sys/systm.h>
  52 #include <sys/malloc.h>
  53 #include <sys/proc.h>
  54 #include <sys/vmmeter.h>
  55 #include <sys/vnode.h>
  56 #include <sys/xio.h>
  57 #include <sys/sfbuf.h>
  58
  59 #include <vm/vm.h>
  60 #include <vm/vm_param.h>
  61 #include <sys/lock.h>
  62 #include <vm/vm_kern.h>
  63 #include <vm/pmap.h>
  64 #include <vm/vm_map.h>
  65 #include <vm/vm_object.h>
  66 #include <vm/vm_page.h>
  67 #include <vm/vm_pageout.h>
  68 #include <vm/vm_pager.h>
  69 #include <vm/vm_extern.h>
  70 #include <vm/vm_page2.h>
  71
  72 /*
  73  * Just do basic initialization of an empty XIO
  74  */
  75 void
  76 xio_init(xio_t xio)
  77 {
  78     xio->xio_flags = 0;
  79     xio->xio_bytes = 0;
  80     xio->xio_error = 0;
  81     xio->xio_offset = 0;
  82     xio->xio_npages = 0;
  83     xio->xio_pages = xio->xio_internal_pages;
  84 }
  85
  86 /*
  87  * Initialize an XIO given a userspace buffer.  0 is returned on success,
  88  * an error code on failure.  The actual number of bytes that could be
  89  * accomodated in the XIO will be stored in xio_bytes and the page offset
  90  * will be stored in xio_offset.
  91  */
  92 int
  93 xio_init_ubuf(xio_t xio, void *ubase, size_t ubytes, int flags)
  94 {
  95     vm_offset_t addr;
  96     vm_paddr_t paddr;
  97     vm_page_t m;
  98     int i;
  99     int n;
 100     int s;
 101     int vmprot;
 102
 103     addr = trunc_page((vm_offset_t)ubase);
 104     xio->xio_flags = flags;
 105     xio->xio_bytes = 0;
 106     xio->xio_error = 0;
 107     if (ubytes == 0) {
 108         xio->xio_offset = 0;
 109         xio->xio_npages = 0;
 110     } else {
 111         vmprot = (flags & XIOF_WRITE) ? VM_PROT_WRITE : VM_PROT_READ;
 112         xio->xio_offset = (vm_offset_t)ubase & PAGE_MASK;
 113         xio->xio_pages = xio->xio_internal_pages;
 114         if ((n = PAGE_SIZE - xio->xio_offset) > ubytes)
 115             n = ubytes;
 116         for (i = 0; n && i < XIO_INTERNAL_PAGES; ++i) {
 117             if (vm_fault_quick((caddr_t)addr, vmprot) < 0)
 118                 break;
 119             if ((paddr = pmap_kextract(addr)) == 0)
 120                 break;
 121             s = splvm();
 122             m = PHYS_TO_VM_PAGE(paddr);
 123             vm_page_hold(m);
 124             splx(s);
 125             xio->xio_pages[i] = m;
 126             ubytes -= n;
 127             xio->xio_bytes += n;
 128             if ((n = ubytes) > PAGE_SIZE)
 129                 n = PAGE_SIZE;
 130             addr += PAGE_SIZE;
 131         }
 132         xio->xio_npages = i;
 133
 134         /*
 135          * If a failure occured clean out what we loaded and return EFAULT.
 136          * Return 0 on success.
 137          */
 138         if (i < XIO_INTERNAL_PAGES && n) {
 139             xio_release(xio);
 140             xio->xio_error = EFAULT;
 141         }
 142     }
 143     return(xio->xio_error);
 144 }
 145
 146 /*
 147  * Initialize an XIO given a kernelspace buffer.  0 is returned on success,
 148  * an error code on failure.  The actual number of bytes that could be
 149  * accomodated in the XIO will be stored in xio_bytes and the page offset
 150  * will be stored in xio_offset.
 151  */
 152 int
 153 xio_init_kbuf(xio_t xio, void *kbase, size_t kbytes)
 154 {
 155     vm_offset_t addr;
 156     vm_paddr_t paddr;
 157     vm_page_t m;
 158     int i;
 159     int n;
 160     int s;
 161
 162     addr = trunc_page((vm_offset_t)kbase);
 163     xio->xio_flags = 0;
 164     xio->xio_offset = (vm_offset_t)kbase & PAGE_MASK;
 165     xio->xio_bytes = 0;
 166     xio->xio_pages = xio->xio_internal_pages;
 167     xio->xio_error = 0;
 168     if ((n = PAGE_SIZE - xio->xio_offset) > kbytes)
 169         n = kbytes;
 170     for (i = 0; n && i < XIO_INTERNAL_PAGES; ++i) {
 171         if ((paddr = pmap_kextract(addr)) == 0)
 172             break;
 173         s = splvm();
 174         m = PHYS_TO_VM_PAGE(paddr);
 175         vm_page_hold(m);
 176         splx(s);
 177         xio->xio_pages[i] = m;
 178         kbytes -= n;
 179         xio->xio_bytes += n;
 180         if ((n = kbytes) > PAGE_SIZE)
 181             n = PAGE_SIZE;
 182         addr += PAGE_SIZE;
 183     }
 184     xio->xio_npages = i;
 185
 186     /*
 187      * If a failure occured clean out what we loaded and return EFAULT.
 188      * Return 0 on success.
 189      */
 190     if (i < XIO_INTERNAL_PAGES && n) {
 191         xio_release(xio);
 192         xio->xio_error = EFAULT;
 193     }
 194     return(xio->xio_error);
 195 }
 196
 197 /*
 198  * Cleanup an XIO so it can be destroyed.  The pages associated with the
 199  * XIO are released.
 200  */
 201 void
 202 xio_release(xio_t xio)
 203 {
 204     int i;
 205     int s;
 206     vm_page_t m;
 207
 208     s = splvm();
 209     for (i = 0; i < xio->xio_npages; ++i) {
 210         m = xio->xio_pages[i];
 211         vm_page_unhold(m);
 212     }
 213     splx(s);
 214     xio->xio_offset = 0;
 215     xio->xio_npages = 0;
 216     xio->xio_bytes = 0;
 217     xio->xio_error = ENOBUFS;
 218 }
 219
 220 /*
 221  * Copy data between an XIO and a UIO.  If the UIO represents userspace it
 222  * must be relative to the current context.
 223  *
 224  * uoffset is the abstracted starting offset in the XIO, not the actual
 225  * offset, and usually starts at 0.
 226  *
 227  * The XIO is not modified.  The UIO is updated to reflect the copy.
 228  *
 229  * UIO_READ     xio -> uio
 230  * UIO_WRITE    uio -> xio
 231  */
 232 int
 233 xio_uio_copy(xio_t xio, int uoffset, struct uio *uio, int *sizep)
 234 {
 235     int error;
 236     int bytes;
 237
 238     bytes = xio->xio_bytes - uoffset;
 239     if (bytes > uio->uio_resid)
 240         bytes = uio->uio_resid;
 241     KKASSERT(bytes >= 0);
 242     error = uiomove_fromphys(xio->xio_pages, xio->xio_offset + uoffset,
 243                                 bytes, uio);
 244     if (error == 0)
 245         *sizep = bytes;
 246     else
 247         *sizep = 0;
 248     return(error);
 249 }
 250
 251 /*
 252  * Copy the specified number of bytes from the xio to a userland
 253  * buffer.  Return an error code or 0 on success.
 254  *
 255  * uoffset is the abstracted starting offset in the XIO, not the actual
 256  * offset, and usually starts at 0.
 257  *
 258  * The XIO is not modified.
 259  */
 260 int
 261 xio_copy_xtou(xio_t xio, int uoffset, void *uptr, int bytes)
 262 {
 263     int i;
 264     int n;
 265     int error;
 266     int offset;
 267     vm_page_t m;
 268     struct sf_buf *sf;
 269
 270     if (bytes > xio->xio_bytes)
 271         return(EFAULT);
 272
 273     offset = (xio->xio_offset + uoffset) & PAGE_MASK;
 274     if ((n = PAGE_SIZE - offset) > bytes)
 275         n = bytes;
 276
 277     error = 0;
 278     for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT;
 279          i < xio->xio_npages;
 280          ++i
 281     ) {
 282         m = xio->xio_pages[i];
 283         sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
 284         error = copyout((char *)sf_buf_kva(sf) + offset, uptr, n);
 285         sf_buf_free(sf);
 286         if (error)
 287             break;
 288         bytes -= n;
 289         uptr = (char *)uptr + n;
 290         if (bytes == 0)
 291             break;
 292         if ((n = bytes) > PAGE_SIZE)
 293             n = PAGE_SIZE;
 294         offset = 0;
 295     }
 296     return(error);
 297 }
 298
 299 /*
 300  * Copy the specified number of bytes from the xio to a kernel
 301  * buffer.  Return an error code or 0 on success.
 302  *
 303  * uoffset is the abstracted starting offset in the XIO, not the actual
 304  * offset, and usually starts at 0.
 305  *
 306  * The XIO is not modified.
 307  */
 308 int
 309 xio_copy_xtok(xio_t xio, int uoffset, void *kptr, int bytes)
 310 {
 311     int i;
 312     int n;
 313     int error;
 314     int offset;
 315     vm_page_t m;
 316     struct sf_buf *sf;
 317
 318     if (bytes + uoffset > xio->xio_bytes)
 319         return(EFAULT);
 320
 321     offset = (xio->xio_offset + uoffset) & PAGE_MASK;
 322     if ((n = PAGE_SIZE - offset) > bytes)
 323         n = bytes;
 324
 325     error = 0;
 326     for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT;
 327          i < xio->xio_npages;
 328          ++i
 329     ) {
 330         m = xio->xio_pages[i];
 331         sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
 332         bcopy((char *)sf_buf_kva(sf) + offset, kptr, n);
 333         sf_buf_free(sf);
 334         bytes -= n;
 335         kptr = (char *)kptr + n;
 336         if (bytes == 0)
 337             break;
 338         if ((n = bytes) > PAGE_SIZE)
 339             n = PAGE_SIZE;
 340         offset = 0;
 341     }
 342     return(error);
 343 }
 344