FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_xio.c

     /*
      * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
      * 
      * This code is derived from software contributed to The DragonFly Project
      * by Matthew Dillon <dillon@backplane.com>
      * 
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in
     *    the documentation and/or other materials provided with the
     *    distribution.
     * 3. Neither the name of The DragonFly Project nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific, prior written permission.
     * 
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
     * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
     * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     * 
     * $DragonFly: src/sys/kern/kern_xio.c,v 1.16 2008/05/09 07:24:45 dillon Exp $
     */
    /*
     * Kernel XIO interface.  An initialized XIO is basically a collection of
     * appropriately held vm_page_t's.  XIO buffers are vmspace agnostic and
     * can represent userspace or kernelspace buffers, and can be passed to
     * foreign threads outside of the originating vmspace.  XIO buffers are
     * not mapped into KVM and thus can be manipulated and passed around with
     * very low overheads.
     *
     * The intent is for XIO to be used in the I/O path, VFS, CAPS, and other
     * places that need to pass (possibly userspace) data between threads.
     *
     * TODO: check for busy page when modifying, check writeable.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/proc.h>
    #include <sys/vmmeter.h>
    #include <sys/vnode.h>
    #include <sys/xio.h>
    
    #include <cpu/lwbuf.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <sys/lock.h>
    #include <vm/vm_kern.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pageout.h>
    #include <vm/vm_pager.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_page2.h>
    
    /*
     * Just do basic initialization of an empty XIO
     */
    void
    xio_init(xio_t xio)
    {
        xio->xio_flags = 0;
        xio->xio_bytes = 0;
        xio->xio_error = 0;
        xio->xio_offset = 0;
        xio->xio_npages = 0;
        xio->xio_pages = xio->xio_internal_pages;
    }
    
    /*
     * Initialize an XIO given a userspace buffer.  0 is returned on success,
     * an error code on failure.  The actual number of bytes that could be
     * accomodated in the XIO will be stored in xio_bytes and the page offset
     * will be stored in xio_offset.
     */
    int
    xio_init_ubuf(xio_t xio, void *ubase, size_t ubytes, int flags)
    {
        vm_offset_t addr;
        vm_page_t m;
        vm_page_t m0;
        int error;
       int i;
       int n;
       int vmprot;
   
       addr = trunc_page((vm_offset_t)ubase);
       xio->xio_flags = flags;
       xio->xio_bytes = 0;
       xio->xio_error = 0;
       if (ubytes == 0) {
           xio->xio_offset = 0;
           xio->xio_npages = 0;
       } else {
           vmprot = (flags & XIOF_WRITE) ? VM_PROT_WRITE : VM_PROT_READ;
           xio->xio_offset = (vm_offset_t)ubase & PAGE_MASK;
           xio->xio_pages = xio->xio_internal_pages;
           if ((n = PAGE_SIZE - xio->xio_offset) > ubytes)
               n = ubytes;
           m0 = NULL;
           for (i = 0; n && i < XIO_INTERNAL_PAGES; ++i) {
               m = vm_fault_page_quick(addr, vmprot, &error);
               if (m == NULL)
                   break;
               xio->xio_pages[i] = m;
               ubytes -= n;
               xio->xio_bytes += n;
               if ((n = ubytes) > PAGE_SIZE)
                   n = PAGE_SIZE;
               addr += PAGE_SIZE;
   
               /*
                * Check linearity, used by syslink to memory map DMA buffers.
                */
               if (flags & XIOF_VMLINEAR) {
                   if (i == 0) {
                       m0 = m;
                   } else 
                   if (m->object != m0->object || m->pindex != m0->pindex + i) {
                       error = EINVAL;
                       break;
                   }
               }
           }
           xio->xio_npages = i;
   
           /*
            * If a failure occured clean out what we loaded and return EFAULT.
            * Return 0 on success.  Do not dirty the pages.
            */
           if (i < XIO_INTERNAL_PAGES && n) {
               xio->xio_flags &= ~XIOF_WRITE;
               xio_release(xio);
               xio->xio_error = EFAULT;
           }
       }
       return(xio->xio_error);
   }
   
   /*
    * Initialize an XIO given a kernelspace buffer.  0 is returned on success,
    * an error code on failure.  The actual number of bytes that could be
    * accomodated in the XIO will be stored in xio_bytes and the page offset
    * will be stored in xio_offset.
    */
   int
   xio_init_kbuf(xio_t xio, void *kbase, size_t kbytes)
   {
       vm_offset_t addr;
       vm_paddr_t paddr;
       vm_page_t m;
       int i;
       int n;
   
       addr = trunc_page((vm_offset_t)kbase);
       xio->xio_flags = 0;
       xio->xio_offset = (vm_offset_t)kbase & PAGE_MASK;
       xio->xio_bytes = 0;
       xio->xio_pages = xio->xio_internal_pages;
       xio->xio_error = 0;
       if ((n = PAGE_SIZE - xio->xio_offset) > kbytes)
           n = kbytes;
       for (i = 0; n && i < XIO_INTERNAL_PAGES; ++i) {
           if ((paddr = pmap_kextract(addr)) == 0)
               break;
           m = PHYS_TO_VM_PAGE(paddr);
           vm_page_hold(m);
           xio->xio_pages[i] = m;
           kbytes -= n;
           xio->xio_bytes += n;
           if ((n = kbytes) > PAGE_SIZE)
               n = PAGE_SIZE;
           addr += PAGE_SIZE;
       }
       xio->xio_npages = i;
   
       /*
        * If a failure occured clean out what we loaded and return EFAULT.
        * Return 0 on success.
        */
       if (i < XIO_INTERNAL_PAGES && n) {
           xio_release(xio);
           xio->xio_error = EFAULT;
       }
       return(xio->xio_error);
   }
   
   /*
    * Initialize an XIO given an array of vm_page pointers.  The caller is
    * responsible for any modified state changes for the pages.
    */
   int
   xio_init_pages(xio_t xio, struct vm_page **mbase, int npages, int xflags)
   {
       int i;
   
       KKASSERT(npages <= XIO_INTERNAL_PAGES);
   
       xio->xio_flags = xflags;
       xio->xio_offset = 0;
       xio->xio_bytes = npages * PAGE_SIZE;
       xio->xio_pages = xio->xio_internal_pages;
       xio->xio_npages = npages;
       xio->xio_error = 0;
       for (i = 0; i < npages; ++i) {
           vm_page_hold(mbase[i]);
           xio->xio_pages[i] = mbase[i];
       }
       return(0);
   }
   
   /*
    * Cleanup an XIO so it can be destroyed.  The pages associated with the
    * XIO are released.
    */
   void
   xio_release(xio_t xio)
   {
       int i;
       vm_page_t m;
   
       for (i = 0; i < xio->xio_npages; ++i) {
           m = xio->xio_pages[i];
           if (xio->xio_flags & XIOF_WRITE)
                   vm_page_dirty(m);
           vm_page_unhold(m);
       }
       xio->xio_offset = 0;
       xio->xio_npages = 0;
       xio->xio_bytes = 0;
       xio->xio_error = ENOBUFS;
   }
   
   /*
    * Copy data between an XIO and a UIO.  If the UIO represents userspace it
    * must be relative to the current context.
    *
    * uoffset is the abstracted starting offset in the XIO, not the actual
    * offset, and usually starts at 0.
    *
    * The XIO is not modified.  The UIO is updated to reflect the copy.
    *
    * UIO_READ     xio -> uio
    * UIO_WRITE    uio -> xio
    */
   int
   xio_uio_copy(xio_t xio, int uoffset, struct uio *uio, size_t *sizep)
   {
       size_t bytes;
       int error;
   
       bytes = xio->xio_bytes - uoffset;
       if (bytes > uio->uio_resid)
           bytes = uio->uio_resid;
       KKASSERT(bytes >= 0);
       error = uiomove_fromphys(xio->xio_pages, xio->xio_offset + uoffset, 
                                   bytes, uio);
       if (error == 0)
           *sizep = bytes;
       else
           *sizep = 0;
       return(error);
   }
   
   /*
    * Copy the specified number of bytes from the xio to a userland
    * buffer.  Return an error code or 0 on success.  
    *
    * uoffset is the abstracted starting offset in the XIO, not the actual
    * offset, and usually starts at 0.
    *
    * The XIO is not modified.
    */
   int
   xio_copy_xtou(xio_t xio, int uoffset, void *uptr, int bytes)
   {
       int i;
       int n;
       int error;
       int offset;
       vm_page_t m;
       struct lwbuf *lwb;
       struct lwbuf lwb_cache;
   
       if (uoffset + bytes > xio->xio_bytes)
           return(EFAULT);
   
       offset = (xio->xio_offset + uoffset) & PAGE_MASK;
       if ((n = PAGE_SIZE - offset) > bytes)
           n = bytes;
   
       error = 0;
       for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT; 
            i < xio->xio_npages; 
            ++i
       ) {
           m = xio->xio_pages[i];
           lwb = lwbuf_alloc(m, &lwb_cache);
           error = copyout((char *)lwbuf_kva(lwb) + offset, uptr, n);
           lwbuf_free(lwb);
           if (error)
               break;
           bytes -= n;
           uptr = (char *)uptr + n;
           if (bytes == 0)
               break;
           if ((n = bytes) > PAGE_SIZE)
               n = PAGE_SIZE;
           offset = 0;
       }
       return(error);
   }
   
   /*
    * Copy the specified number of bytes from the xio to a kernel
    * buffer.  Return an error code or 0 on success.
    *
    * uoffset is the abstracted starting offset in the XIO, not the actual
    * offset, and usually starts at 0.
    *
    * The XIO is not modified.
    */
   int
   xio_copy_xtok(xio_t xio, int uoffset, void *kptr, int bytes)
   {
       int i;
       int n;
       int error;
       int offset;
       vm_page_t m;
       struct lwbuf *lwb;
       struct lwbuf lwb_cache;
   
       if (bytes + uoffset > xio->xio_bytes)
           return(EFAULT);
   
       offset = (xio->xio_offset + uoffset) & PAGE_MASK;
       if ((n = PAGE_SIZE - offset) > bytes)
           n = bytes;
   
       error = 0;
       for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT; 
            i < xio->xio_npages; 
            ++i
       ) {
           m = xio->xio_pages[i];
           lwb = lwbuf_alloc(m, &lwb_cache);
           bcopy((char *)lwbuf_kva(lwb) + offset, kptr, n);
           lwbuf_free(lwb);
           bytes -= n;
           kptr = (char *)kptr + n;
           if (bytes == 0)
               break;
           if ((n = bytes) > PAGE_SIZE)
               n = PAGE_SIZE;
           offset = 0;
       }
       return(error);
   }
   
   /*
    * Copy the specified number of bytes from userland to the xio.
    * Return an error code or 0 on success.  
    *
    * uoffset is the abstracted starting offset in the XIO, not the actual
    * offset, and usually starts at 0.
    *
    * Data in pages backing the XIO will be modified.
    */
   int
   xio_copy_utox(xio_t xio, int uoffset, const void *uptr, int bytes)
   {
       int i;
       int n;
       int error;
       int offset;
       vm_page_t m;
       struct lwbuf *lwb;
       struct lwbuf lwb_cache;
   
       if (uoffset + bytes > xio->xio_bytes)
           return(EFAULT);
   
       offset = (xio->xio_offset + uoffset) & PAGE_MASK;
       if ((n = PAGE_SIZE - offset) > bytes)
           n = bytes;
   
       error = 0;
       for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT; 
            i < xio->xio_npages; 
            ++i
       ) {
           m = xio->xio_pages[i];
           lwb = lwbuf_alloc(m, &lwb_cache);
           error = copyin(uptr, (char *)lwbuf_kva(lwb) + offset, n);
           lwbuf_free(lwb);
           if (error)
               break;
           bytes -= n;
           uptr = (const char *)uptr + n;
           if (bytes == 0)
               break;
           if ((n = bytes) > PAGE_SIZE)
               n = PAGE_SIZE;
           offset = 0;
       }
       return(error);
   }
   
   /*
    * Copy the specified number of bytes from the kernel to the xio.
    * Return an error code or 0 on success.  
    *
    * uoffset is the abstracted starting offset in the XIO, not the actual
    * offset, and usually starts at 0.
    *
    * Data in pages backing the XIO will be modified.
    */
   int
   xio_copy_ktox(xio_t xio, int uoffset, const void *kptr, int bytes)
   {
       int i;
       int n;
       int error;
       int offset;
       vm_page_t m;
       struct lwbuf *lwb;
       struct lwbuf lwb_cache;
   
       if (uoffset + bytes > xio->xio_bytes)
           return(EFAULT);
   
       offset = (xio->xio_offset + uoffset) & PAGE_MASK;
       if ((n = PAGE_SIZE - offset) > bytes)
           n = bytes;
   
       error = 0;
       for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT; 
            i < xio->xio_npages; 
            ++i
       ) {
           m = xio->xio_pages[i];
           lwb = lwbuf_alloc(m, &lwb_cache);
           bcopy(kptr, (char *)lwbuf_kva(lwb) + offset, n);
           lwbuf_free(lwb);
           bytes -= n;
           kptr = (const char *)kptr + n;
           if (bytes == 0)
               break;
           if ((n = bytes) > PAGE_SIZE)
               n = PAGE_SIZE;
           offset = 0;
       }
       return(error);
   }

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