text: /*
   * 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.
   */
  /*
   * 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/uio.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 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.
   *
   * WARNING! We cannot map user memory directly into an xio unless we also
   *	    make the mapping use managed pages, otherwise modifications to
   *	    the memory will race against pageouts and flushes.
   */
  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);
  }
  