From f04cf9239addd12d6be9e7ff137262755e3680d3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Fri, 9 Oct 2015 17:17:19 +0200 Subject: util: add linux-only memfd fallback MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement memfd_create() fallback if not available in system libc. memfd_create() is still not included in glibc today, atlhough it's been available since Linux 3.17 in Oct 2014. memfd has numerous advantages over traditional shm/mmap for ipc memory sharing with fd handler, which we are going to make use of for vhost-user logging memory in following patches. The next patches are going to introduce helpers to use best practices of memfd usage and provide some compatibility fallback. memfd.c is thus temporarily useless and eventually empty if memfd_create() is provided by the system. Signed-off-by: Marc-André Lureau Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Tested-by: Thibaut Collet --- util/Makefile.objs | 1 + util/memfd.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+) create mode 100644 util/memfd.c (limited to 'util') diff --git a/util/Makefile.objs b/util/Makefile.objs index f217901..bab1722 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -6,6 +6,7 @@ util-obj-$(CONFIG_POSIX) += oslib-posix.o util-obj-$(CONFIG_POSIX) += qemu-openpty.o util-obj-$(CONFIG_POSIX) += qemu-thread-posix.o util-obj-$(CONFIG_WIN32) += event_notifier-win32.o +util-obj-$(CONFIG_POSIX) += memfd.o util-obj-$(CONFIG_WIN32) += oslib-win32.o util-obj-$(CONFIG_WIN32) += qemu-thread-win32.o util-obj-y += envlist.o path.o module.o diff --git a/util/memfd.c b/util/memfd.c new file mode 100644 index 0000000..c509692 --- /dev/null +++ b/util/memfd.c @@ -0,0 +1,54 @@ +/* + * memfd.c + * + * Copyright (c) 2015 Red Hat, Inc. + * + * QEMU library functions on POSIX which are shared between QEMU and + * the QEMU tools. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" + +#include "qemu/memfd.h" + +#ifdef CONFIG_MEMFD +#include +#elif defined CONFIG_LINUX +#include +#include + +inline static int memfd_create(const char *name, unsigned int flags) +{ +#ifdef __NR_memfd_create + return syscall(__NR_memfd_create, name, flags); +#else + return -1; +#endif +} +#endif + +#ifndef MFD_CLOEXEC +#define MFD_CLOEXEC 0x0001U +#endif + +#ifndef MFD_ALLOW_SEALING +#define MFD_ALLOW_SEALING 0x0002U +#endif -- cgit v1.1