/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
 * Copyright (c) 1982, 1986, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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 University 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 REGENTS 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 REGENTS 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.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/uio.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_page.h>

#include <machine/vmparam.h>
#include <machine/md_var.h>

/*
 * Implement uiomove(9) from physical memory using the direct map to
 * avoid the creation and destruction of ephemeral mappings.
 */
int
uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
{
        struct iovec *iov;
        void *cp, *vaddr;
        vm_offset_t page_offset;
        size_t cnt;
        int error = 0;
        int save;
        bool mapped;

        KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
            ("uiomove_fromphys: mode"));
        KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
            ("uiomove_fromphys proc"));
        KASSERT(uio->uio_resid >= 0,
            ("%s: uio %p resid underflow", __func__, uio));

        save = curthread_pflags_set(TDP_DEADLKTREAT);
        mapped = false;
        while (n > 0 && uio->uio_resid) {
                KASSERT(uio->uio_iovcnt > 0,
                    ("%s: uio %p iovcnt underflow", __func__, uio));

                iov = uio->uio_iov;
                cnt = iov->iov_len;
                if (cnt == 0) {
                        uio->uio_iov++;
                        uio->uio_iovcnt--;
                        continue;
                }
                if (cnt > n)
                        cnt = n;
                page_offset = offset & PAGE_MASK;
                cnt = min(cnt, PAGE_SIZE - page_offset);
                if (uio->uio_segflg != UIO_NOCOPY) {
                        mapped = pmap_map_io_transient(
                            &ma[offset >> PAGE_SHIFT], &vaddr, 1, true);
                        cp = (char *)vaddr + page_offset;
                }
                error = uiomove_step(cp, iov->iov_base, cnt, uio);
                if (__predict_false(mapped)) {
                        pmap_unmap_io_transient(&ma[offset >> PAGE_SHIFT],
                            &vaddr, 1, true);
                        mapped = false;
                }
                if (error != 0)
                        break;
                iov->iov_base = (char *)iov->iov_base + cnt;
                iov->iov_len -= cnt;
                uio->uio_resid -= cnt;
                uio->uio_offset += cnt;
                offset += cnt;
                n -= cnt;
        }
        curthread_pflags_restore(save);
        return (error);
}

int
uiomove_mem(enum uiomove_mem_req req, struct uio *uio)
{
        struct iovec *iov;
        void *p, *vd;
        ssize_t orig_resid;
        vm_prot_t prot;
        u_long v;
        u_int c;
        int error;

        error = 0;
        orig_resid = uio->uio_resid;
        while (uio->uio_resid > 0 && error == 0) {
                iov = uio->uio_iov;
                if (iov->iov_len == 0) {
                        uio->uio_iov++;
                        uio->uio_iovcnt--;
                        if (uio->uio_iovcnt < 0)
                                panic("memrw");
                        continue;
                }
                v = uio->uio_offset;
                c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));

                switch (req) {
                case UIO_MEM_KMEM:
                        /*
                         * Since c is clamped to be less or equal than
                         * PAGE_SIZE, the uiomove() call does not
                         * access past the end of the direct map.
                         */
                        if (v >= kva_layout.dmap_low &&
                            v < kva_layout.dmap_high) {
                                error = uiomove((void *)v, c, uio);
                                break;
                        }

                        switch (uio->uio_rw) {
                        case UIO_READ:
                                prot = VM_PROT_READ;
                                break;
                        case UIO_WRITE:
                                prot = VM_PROT_WRITE;
                                break;
                        }

                        if (!kernacc((void *)v, c, prot)) {
                                error = EFAULT;
                                break;
                        }

                        /*
                         * If the extracted address is not accessible
                         * through the direct map, then we make a
                         * private (uncached) mapping because we can't
                         * depend on the existing kernel mapping
                         * remaining valid until the completion of
                         * uiomove().
                         *
                         * XXX We cannot provide access to the
                         * physical page 0 mapped into KVA.
                         */
                        v = pmap_extract(kernel_pmap, v);
                        if (v == 0) {
                                error = EFAULT;
                                break;
                        }
                        /* FALLTHROUGH */
                case UIO_MEM_MEM:
                        if (v < dmaplimit) {
                                vd = PHYS_TO_DMAP(v);
                                error = uiomove(vd, c, uio);
                                break;
                        }
                        if (v > cpu_getmaxphyaddr()) {
                                error = EFAULT;
                                break;
                        }
                        p = pmap_mapdev(v, PAGE_SIZE);
                        error = uiomove(p, c, uio);
                        pmap_unmapdev(p, PAGE_SIZE);
                        break;
                }
        }
        /*
         * Don't return error if any byte was written.  Read and write
         * can return error only if no i/o was performed.
         */
        if (uio->uio_resid != orig_resid)
                error = 0;
        return (error);
}