subr_uio.c

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/*-
 * 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.
 * 4. 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.
 *
 *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include "opt_zero.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#ifdef ZERO_COPY_SOCKETS
#include <vm/vm_object.h>
#endif

SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, UIO_MAXIOV,
        "Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");

static int uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault);

#ifdef ZERO_COPY_SOCKETS
/* Declared in uipc_socket.c */
extern int so_zero_copy_receive;

/*
 * Identify the physical page mapped at the given kernel virtual
 * address.  Insert this physical page into the given address space at
 * the given virtual address, replacing the physical page, if any,
 * that already exists there.
 */
static int
vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
{
        vm_map_t map = mapa;
        vm_page_t kern_pg, user_pg;
        vm_object_t uobject;
        vm_map_entry_t entry;
        vm_pindex_t upindex;
        vm_prot_t prot;
        boolean_t wired;

        KASSERT((uaddr & PAGE_MASK) == 0,
            ("vm_pgmoveco: uaddr is not page aligned"));

        /*
         * Herein the physical page is validated and dirtied.  It is
         * unwired in sf_buf_mext().
         */
        kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
        kern_pg->valid = VM_PAGE_BITS_ALL;
        KASSERT(kern_pg->queue == PQ_NONE && kern_pg->wire_count == 1,
            ("vm_pgmoveco: kern_pg is not correctly wired"));

        if ((vm_map_lookup(&map, uaddr,
                           VM_PROT_WRITE, &entry, &uobject,
                           &upindex, &prot, &wired)) != KERN_SUCCESS) {
                return(EFAULT);
        }
        VM_OBJECT_LOCK(uobject);
retry:
        if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
                if (vm_page_sleep_if_busy(user_pg, TRUE, "vm_pgmoveco"))
                        goto retry;
                vm_page_lock(user_pg);
                pmap_remove_all(user_pg);
                vm_page_free(user_pg);
                vm_page_unlock(user_pg);
        } else {
                /*
                 * Even if a physical page does not exist in the
                 * object chain's first object, a physical page from a
                 * backing object may be mapped read only.
                 */
                if (uobject->backing_object != NULL)
                        pmap_remove(map->pmap, uaddr, uaddr + PAGE_SIZE);
        }
        vm_page_insert(kern_pg, uobject, upindex);
        vm_page_dirty(kern_pg);
        VM_OBJECT_UNLOCK(uobject);
        vm_map_lookup_done(map, entry);
        return(KERN_SUCCESS);
}
#endif /* ZERO_COPY_SOCKETS */

int
copyin_nofault(const void *udaddr, void *kaddr, size_t len)
{
        int error, save;

        save = vm_fault_disable_pagefaults();
        error = copyin(udaddr, kaddr, len);
        vm_fault_enable_pagefaults(save);
        return (error);
}

int
copyout_nofault(const void *kaddr, void *udaddr, size_t len)
{
        int error, save;

        save = vm_fault_disable_pagefaults();
        error = copyout(kaddr, udaddr, len);
        vm_fault_enable_pagefaults(save);
        return (error);
}

#define PHYS_PAGE_COUNT(len)    (howmany(len, PAGE_SIZE) + 1)

int
physcopyin(void *src, vm_paddr_t dst, size_t len)
{
        vm_page_t m[PHYS_PAGE_COUNT(len)];
        struct iovec iov[1];
        struct uio uio;
        int i;

        iov[0].iov_base = src;
        iov[0].iov_len = len;
        uio.uio_iov = iov;
        uio.uio_iovcnt = 1;
        uio.uio_offset = 0;
        uio.uio_resid = len;
        uio.uio_segflg = UIO_SYSSPACE;
        uio.uio_rw = UIO_WRITE;
        for (i = 0; i < PHYS_PAGE_COUNT(len); i++, dst += PAGE_SIZE)
                m[i] = PHYS_TO_VM_PAGE(dst);
        return (uiomove_fromphys(m, dst & PAGE_MASK, len, &uio));
}

int
physcopyout(vm_paddr_t src, void *dst, size_t len)
{
        vm_page_t m[PHYS_PAGE_COUNT(len)];
        struct iovec iov[1];
        struct uio uio;
        int i;

        iov[0].iov_base = dst;
        iov[0].iov_len = len;
        uio.uio_iov = iov;
        uio.uio_iovcnt = 1;
        uio.uio_offset = 0;
        uio.uio_resid = len;
        uio.uio_segflg = UIO_SYSSPACE;
        uio.uio_rw = UIO_READ;
        for (i = 0; i < PHYS_PAGE_COUNT(len); i++, src += PAGE_SIZE)
                m[i] = PHYS_TO_VM_PAGE(src);
        return (uiomove_fromphys(m, src & PAGE_MASK, len, &uio));
}

#undef PHYS_PAGE_COUNT

int
uiomove(void *cp, int n, struct uio *uio)
{

        return (uiomove_faultflag(cp, n, uio, 0));
}

int
uiomove_nofault(void *cp, int n, struct uio *uio)
{

        return (uiomove_faultflag(cp, n, uio, 1));
}

static int
uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
{
        struct thread *td;
        struct iovec *iov;
        size_t cnt;
        int error, newflags, save;

        td = curthread;
        error = 0;

        KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
            ("uiomove: mode"));
        KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == td,
            ("uiomove proc"));
        if (!nofault)
                WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
                    "Calling uiomove()");

        /* XXX does it make a sense to set TDP_DEADLKTREAT for UIO_SYSSPACE ? */
        newflags = TDP_DEADLKTREAT;
        if (uio->uio_segflg == UIO_USERSPACE && nofault) {
                /*
                 * Fail if a non-spurious page fault occurs.
                 */
                newflags |= TDP_NOFAULTING | TDP_RESETSPUR;
        }
        save = curthread_pflags_set(newflags);

        while (n > 0 && uio->uio_resid) {
                iov = uio->uio_iov;
                cnt = iov->iov_len;
                if (cnt == 0) {
                        uio->uio_iov++;
                        uio->uio_iovcnt--;
                        continue;
                }
                if (cnt > n)
                        cnt = n;

                switch (uio->uio_segflg) {

                case UIO_USERSPACE:
                        maybe_yield();
                        if (uio->uio_rw == UIO_READ)
                                error = copyout(cp, iov->iov_base, cnt);
                        else
                                error = copyin(iov->iov_base, cp, cnt);
                        if (error)
                                goto out;
                        break;

                case UIO_SYSSPACE:
                        if (uio->uio_rw == UIO_READ)
                                bcopy(cp, iov->iov_base, cnt);
                        else
                                bcopy(iov->iov_base, cp, cnt);
                        break;
                case UIO_NOCOPY:
                        break;
                }
                iov->iov_base = (char *)iov->iov_base + cnt;
                iov->iov_len -= cnt;
                uio->uio_resid -= cnt;
                uio->uio_offset += cnt;
                cp = (char *)cp + cnt;
                n -= cnt;
        }
out:
        curthread_pflags_restore(save);
        return (error);
}

/*
 * Wrapper for uiomove() that validates the arguments against a known-good
 * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
 * is almost definitely a bad thing, so we catch that here as well.  We
 * return a runtime failure, but it might be desirable to generate a runtime
 * assertion failure instead.
 */
int
uiomove_frombuf(void *buf, int buflen, struct uio *uio)
{
        size_t offset, n;

        if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
            (offset = uio->uio_offset) != uio->uio_offset)
                return (EINVAL);
        if (buflen <= 0 || offset >= buflen)
                return (0);
        if ((n = buflen - offset) > IOSIZE_MAX)
                return (EINVAL);
        return (uiomove((char *)buf + offset, n, uio));
}

#ifdef ZERO_COPY_SOCKETS
/*
 * Experimental support for zero-copy I/O
 */
static int
userspaceco(void *cp, u_int cnt, struct uio *uio, int disposable)
{
        struct iovec *iov;
        int error;

        iov = uio->uio_iov;
        if (uio->uio_rw == UIO_READ) {
                if ((so_zero_copy_receive != 0)
                 && ((cnt & PAGE_MASK) == 0)
                 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
                 && ((uio->uio_offset & PAGE_MASK) == 0)
                 && ((((intptr_t) cp) & PAGE_MASK) == 0)
                 && (disposable != 0)) {
                        /* SOCKET: use page-trading */
                        /*
                         * We only want to call vm_pgmoveco() on
                         * disposeable pages, since it gives the
                         * kernel page to the userland process.
                         */
                        error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
                            (vm_offset_t)cp, (vm_offset_t)iov->iov_base);

                        /*
                         * If we get an error back, attempt
                         * to use copyout() instead.  The
                         * disposable page should be freed
                         * automatically if we weren't able to move
                         * it into userland.
                         */
                        if (error != 0)
                                error = copyout(cp, iov->iov_base, cnt);
                } else {
                        error = copyout(cp, iov->iov_base, cnt);
                }
        } else {
                error = copyin(iov->iov_base, cp, cnt);
        }
        return (error);
}

int
uiomoveco(void *cp, int n, struct uio *uio, int disposable)
{
        struct iovec *iov;
        u_int cnt;
        int error;

        KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
            ("uiomoveco: mode"));
        KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
            ("uiomoveco proc"));

        while (n > 0 && uio->uio_resid) {
                iov = uio->uio_iov;
                cnt = iov->iov_len;
                if (cnt == 0) {
                        uio->uio_iov++;
                        uio->uio_iovcnt--;
                        continue;
                }
                if (cnt > n)
                        cnt = n;

                switch (uio->uio_segflg) {

                case UIO_USERSPACE:
                        maybe_yield();
                        error = userspaceco(cp, cnt, uio, disposable);
                        if (error)
                                return (error);
                        break;

                case UIO_SYSSPACE:
                        if (uio->uio_rw == UIO_READ)
                                bcopy(cp, iov->iov_base, cnt);
                        else
                                bcopy(iov->iov_base, cp, cnt);
                        break;
                case UIO_NOCOPY:
                        break;
                }
                iov->iov_base = (char *)iov->iov_base + cnt;
                iov->iov_len -= cnt;
                uio->uio_resid -= cnt;
                uio->uio_offset += cnt;
                cp = (char *)cp + cnt;
                n -= cnt;
        }
        return (0);
}
#endif /* ZERO_COPY_SOCKETS */

/*
 * Give next character to user as result of read.
 */
int
ureadc(int c, struct uio *uio)
{
        struct iovec *iov;
        char *iov_base;

        WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
            "Calling ureadc()");

again:
        if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
                panic("ureadc");
        iov = uio->uio_iov;
        if (iov->iov_len == 0) {
                uio->uio_iovcnt--;
                uio->uio_iov++;
                goto again;
        }
        switch (uio->uio_segflg) {

        case UIO_USERSPACE:
                if (subyte(iov->iov_base, c) < 0)
                        return (EFAULT);
                break;

        case UIO_SYSSPACE:
                iov_base = iov->iov_base;
                *iov_base = c;
                iov->iov_base = iov_base;
                break;

        case UIO_NOCOPY:
                break;
        }
        iov->iov_base = (char *)iov->iov_base + 1;
        iov->iov_len--;
        uio->uio_resid--;
        uio->uio_offset++;
        return (0);
}

int
copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
    int seg)
{
        int error = 0;

        switch (seg) {
        case UIO_USERSPACE:
                error = copyin(src, dst, len);
                break;
        case UIO_SYSSPACE:
                bcopy(src, dst, len);
                break;
        default:
                panic("copyinfrom: bad seg %d\n", seg);
        }
        return (error);
}

int
copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
    size_t * __restrict copied, int seg)
{
        int error = 0;

        switch (seg) {
        case UIO_USERSPACE:
                error = copyinstr(src, dst, len, copied);
                break;
        case UIO_SYSSPACE:
                error = copystr(src, dst, len, copied);
                break;
        default:
                panic("copyinstrfrom: bad seg %d\n", seg);
        }
        return (error);
}

int
copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
{
        u_int iovlen;

        *iov = NULL;
        if (iovcnt > UIO_MAXIOV)
                return (error);
        iovlen = iovcnt * sizeof (struct iovec);
        *iov = malloc(iovlen, M_IOV, M_WAITOK);
        error = copyin(iovp, *iov, iovlen);
        if (error) {
                free(*iov, M_IOV);
                *iov = NULL;
        }
        return (error);
}

int
copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
{
        struct iovec *iov;
        struct uio *uio;
        u_int iovlen;
        int error, i;

        *uiop = NULL;
        if (iovcnt > UIO_MAXIOV)
                return (EINVAL);
        iovlen = iovcnt * sizeof (struct iovec);
        uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
        iov = (struct iovec *)(uio + 1);
        error = copyin(iovp, iov, iovlen);
        if (error) {
                free(uio, M_IOV);
                return (error);
        }
        uio->uio_iov = iov;
        uio->uio_iovcnt = iovcnt;
        uio->uio_segflg = UIO_USERSPACE;
        uio->uio_offset = -1;
        uio->uio_resid = 0;
        for (i = 0; i < iovcnt; i++) {
                if (iov->iov_len > IOSIZE_MAX - uio->uio_resid) {
                        free(uio, M_IOV);
                        return (EINVAL);
                }
                uio->uio_resid += iov->iov_len;
                iov++;
        }
        *uiop = uio;
        return (0);
}

struct uio *
cloneuio(struct uio *uiop)
{
        struct uio *uio;
        int iovlen;

        iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
        uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
        *uio = *uiop;
        uio->uio_iov = (struct iovec *)(uio + 1);
        bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
        return (uio);
}

/*
 * Map some anonymous memory in user space of size sz, rounded up to the page
 * boundary.
 */
int
copyout_map(struct thread *td, vm_offset_t *addr, size_t sz)
{
        struct vmspace *vms;
        int error;
        vm_size_t size;

        vms = td->td_proc->p_vmspace;

        /*
         * Map somewhere after heap in process memory.
         */
        PROC_LOCK(td->td_proc);
        *addr = round_page((vm_offset_t)vms->vm_daddr +
            lim_max(td->td_proc, RLIMIT_DATA));
        PROC_UNLOCK(td->td_proc);

        /* round size up to page boundry */
        size = (vm_size_t)round_page(sz);

        error = vm_mmap(&vms->vm_map, addr, size, PROT_READ | PROT_WRITE,
            VM_PROT_ALL, MAP_PRIVATE | MAP_ANON, OBJT_DEFAULT, NULL, 0);

        return (error);
}

/*
 * Unmap memory in user space.
 */
int
copyout_unmap(struct thread *td, vm_offset_t addr, size_t sz)
{
        vm_map_t map;
        vm_size_t size;

        if (sz == 0)
                return (0);

        map = &td->td_proc->p_vmspace->vm_map;
        size = (vm_size_t)round_page(sz);

        if (vm_map_remove(map, addr, addr + size) != KERN_SUCCESS)
                return (EINVAL);

        return (0);
}