/*      $OpenBSD: uvm_io.c,v 1.30 2022/10/07 14:59:39 deraadt Exp $     */
/*      $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $  */

/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
 */

/*
 * uvm_io.c: uvm i/o ops
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mman.h>
#include <sys/uio.h>

#include <uvm/uvm.h>

/*
 * functions
 */

/*
 * uvm_io: perform I/O on a map
 *
 * => caller must have a reference to "map" so that it doesn't go away
 *    while we are working.
 */

int
uvm_io(vm_map_t map, struct uio *uio, int flags)
{
        vaddr_t baseva, endva, pageoffset, kva;
        vsize_t chunksz, togo, sz;
        struct uvm_map_deadq dead_entries;
        int error, extractflags;

        /*
         * step 0: sanity checks and set up for copy loop.  start with a
         * large chunk size.  if we have trouble finding vm space we will
         * reduce it.
         */
        if (uio->uio_resid == 0)
                return(0);
        togo = uio->uio_resid;

        baseva = (vaddr_t) uio->uio_offset;
        endva = baseva + (togo - 1);

        if (endva < baseva)   /* wrap around? */
                return(EIO);

        if (baseva >= VM_MAXUSER_ADDRESS)
                return(0);
        if (endva >= VM_MAXUSER_ADDRESS)
                /* EOF truncate */
                togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
        pageoffset = baseva & PAGE_MASK;
        baseva = trunc_page(baseva);
        chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
        error = 0;

        extractflags = 0;
        if (flags & UVM_IO_FIXPROT)
                extractflags |= UVM_EXTRACT_FIXPROT;

        /*
         * step 1: main loop...  while we've got data to move
         */
        for (/*null*/; togo > 0 ; pageoffset = 0) {

                /*
                 * step 2: extract mappings from the map into kernel_map
                 */
                error = uvm_map_extract(map, baseva, chunksz, &kva,
                    extractflags);
                if (error) {

                        /* retry with a smaller chunk... */
                        if (error == ENOMEM && chunksz > PAGE_SIZE) {
                                chunksz = trunc_page(chunksz / 2);
                                if (chunksz < PAGE_SIZE)
                                        chunksz = PAGE_SIZE;
                                continue;
                        }

                        break;
                }

                /*
                 * step 3: move a chunk of data
                 */
                sz = chunksz - pageoffset;
                if (sz > togo)
                        sz = togo;
                error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
                togo -= sz;
                baseva += chunksz;


                /*
                 * step 4: unmap the area of kernel memory
                 */
                vm_map_lock(kernel_map);
                TAILQ_INIT(&dead_entries);
                uvm_unmap_remove(kernel_map, kva, kva+chunksz,
                    &dead_entries, FALSE, TRUE, FALSE);
                vm_map_unlock(kernel_map);
                uvm_unmap_detach(&dead_entries, AMAP_REFALL);

                if (error)
                        break;
        }

        return (error);
}