diff options
Diffstat (limited to 'sys/kern/uipc_cow.c')
| -rw-r--r-- | sys/kern/uipc_cow.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/sys/kern/uipc_cow.c b/sys/kern/uipc_cow.c new file mode 100644 index 0000000..654b6d7 --- /dev/null +++ b/sys/kern/uipc_cow.c @@ -0,0 +1,181 @@ +/*-- + * Copyright (c) 1997, Duke University + * All rights reserved. + * + * Author: + * Andrew Gallatin <gallatin@cs.duke.edu> + * + * 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. The name of Duke University may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY DUKE UNIVERSITY ``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 DUKE UNIVERSITY 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 PROFITSOR 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. + */ + +/* + * This is a set of routines for enabling and disabling copy on write + * protection for data written into sockets. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/sysctl.h> +#include <sys/kernel.h> +#include <sys/proc.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#include <sys/mbuf.h> +#include <sys/sf_buf.h> +#include <sys/socketvar.h> +#include <sys/uio.h> + +#include <vm/vm.h> +#include <vm/vm_extern.h> +#include <vm/vm_param.h> +#include <vm/pmap.h> +#include <vm/vm_map.h> +#include <vm/vm_page.h> +#include <vm/vm_object.h> + +FEATURE(zero_copy_sockets, "Zero copy sockets support"); + +struct netsend_cow_stats { + int attempted; + int fail_not_mapped; + int fail_sf_buf; + int success; + int iodone; +}; + +static struct netsend_cow_stats socow_stats; + +static void socow_iodone(void *addr, void *args); + +static void +socow_iodone(void *addr, void *args) +{ + struct sf_buf *sf; + vm_page_t pp; + + sf = args; + pp = sf_buf_page(sf); + sf_buf_free(sf); + /* remove COW mapping */ + vm_page_lock(pp); + vm_page_cowclear(pp); + vm_page_unwire(pp, 0); + /* + * Check for the object going away on us. This can + * happen since we don't hold a reference to it. + * If so, we're responsible for freeing the page. + */ + if (pp->wire_count == 0 && pp->object == NULL) + vm_page_free(pp); + vm_page_unlock(pp); + socow_stats.iodone++; +} + +int +socow_setup(struct mbuf *m0, struct uio *uio) +{ + struct sf_buf *sf; + vm_page_t pp; + struct iovec *iov; + struct vmspace *vmspace; + struct vm_map *map; + vm_offset_t offset, uva; + vm_size_t len; + + socow_stats.attempted++; + vmspace = curproc->p_vmspace; + map = &vmspace->vm_map; + uva = (vm_offset_t) uio->uio_iov->iov_base; + offset = uva & PAGE_MASK; + len = PAGE_SIZE - offset; + + /* + * Verify that access to the given address is allowed from user-space. + */ + if (vm_fault_quick_hold_pages(map, uva, len, VM_PROT_READ, &pp, 1) < + 0) { + socow_stats.fail_not_mapped++; + return(0); + } + + /* + * set up COW + */ + vm_page_lock(pp); + if (vm_page_cowsetup(pp) != 0) { + vm_page_unhold(pp); + vm_page_unlock(pp); + return (0); + } + + /* + * wire the page for I/O + */ + vm_page_wire(pp); + vm_page_unhold(pp); + vm_page_unlock(pp); + /* + * Allocate an sf buf + */ + sf = sf_buf_alloc(pp, SFB_CATCH); + if (sf == NULL) { + vm_page_lock(pp); + vm_page_cowclear(pp); + vm_page_unwire(pp, 0); + /* + * Check for the object going away on us. This can + * happen since we don't hold a reference to it. + * If so, we're responsible for freeing the page. + */ + if (pp->wire_count == 0 && pp->object == NULL) + vm_page_free(pp); + vm_page_unlock(pp); + socow_stats.fail_sf_buf++; + return(0); + } + /* + * attach to mbuf + */ + MEXTADD(m0, sf_buf_kva(sf), PAGE_SIZE, socow_iodone, + (void*)sf_buf_kva(sf), sf, M_RDONLY, EXT_SFBUF); + m0->m_len = len; + m0->m_data = (caddr_t)sf_buf_kva(sf) + offset; + socow_stats.success++; + + iov = uio->uio_iov; + iov->iov_base = (char *)iov->iov_base + m0->m_len; + iov->iov_len -= m0->m_len; + uio->uio_resid -= m0->m_len; + uio->uio_offset += m0->m_len; + if (iov->iov_len == 0) { + uio->uio_iov++; + uio->uio_iovcnt--; + } + + return(m0->m_len); +} |
