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[Qemu-devel] [PATCH v6 04/24] util: add linux-only memfd fallback
From: |
marcandre . lureau |
Subject: |
[Qemu-devel] [PATCH v6 04/24] util: add linux-only memfd fallback |
Date: |
Tue, 29 Sep 2015 18:34:34 +0200 |
From: Marc-André Lureau <address@hidden>
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.
Signed-off-by: Marc-André Lureau <address@hidden>
---
include/qemu/memfd.h | 20 +++++++++++++++++++
util/Makefile.objs | 2 +-
util/memfd.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 77 insertions(+), 1 deletion(-)
create mode 100644 include/qemu/memfd.h
create mode 100644 util/memfd.c
diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h
new file mode 100644
index 0000000..8b1fe6a
--- /dev/null
+++ b/include/qemu/memfd.h
@@ -0,0 +1,20 @@
+#ifndef QEMU_MEMFD_H
+#define QEMU_MEMFD_H
+
+#include "config-host.h"
+
+#ifndef F_LINUX_SPECIFIC_BASE
+#define F_LINUX_SPECIFIC_BASE 1024
+#endif
+
+#ifndef F_ADD_SEALS
+#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
+#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
+
+#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */
+#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */
+#define F_SEAL_GROW 0x0004 /* prevent file from growing */
+#define F_SEAL_WRITE 0x0008 /* prevent writes */
+#endif
+
+#endif /* QEMU_MEMFD_H */
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 114d657..84c5485 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -1,6 +1,6 @@
util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o
util-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o
event_notifier-win32.o
-util-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
event_notifier-posix.o qemu-openpty.o
+util-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
event_notifier-posix.o qemu-openpty.o memfd.o
util-obj-y += envlist.o path.o module.o
util-obj-$(call lnot,$(CONFIG_INT128)) += host-utils.o
util-obj-y += bitmap.o bitops.o hbitmap.o
diff --git a/util/memfd.c b/util/memfd.c
new file mode 100644
index 0000000..a98d57e
--- /dev/null
+++ b/util/memfd.c
@@ -0,0 +1,56 @@
+/*
+ * 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 "config-host.h"
+
+#include "qemu/memfd.h"
+
+#ifdef CONFIG_MEMFD
+#include <sys/memfd.h>
+#elif defined CONFIG_LINUX
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <asm/unistd.h>
+
+#ifndef MFD_CLOEXEC
+#define MFD_CLOEXEC 0x0001U
+#endif
+
+#ifndef MFD_ALLOW_SEALING
+#define MFD_ALLOW_SEALING 0x0002U
+#endif
+
+static inline int memfd_create(const char *name, unsigned int flags)
+{
+ return syscall(__NR_memfd_create, name, flags);
+}
+#else /* !LINUX */
+static inline int memfd_create(const char *name, unsigned int flags)
+{
+ return -1;
+}
+#endif
--
2.4.3
- [Qemu-devel] [PATCH v6 13/24] vhost: use a function for each call, (continued)
- [Qemu-devel] [PATCH v6 16/24] vhost user: add support of live migration, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 23/24] vhost-user-test: check ownership during migration, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 22/24] vhost-user-test: add live-migration test, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 24/24] vhost-user: use an enum helper for features mask, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 01/24] vhost-user: unit test for new messages, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 04/24] util: add linux-only memfd fallback,
marcandre . lureau <=
- [Qemu-devel] [PATCH v6 07/24] vhost: document log resizing, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 12/24] vhost-user: add a migration blocker, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 03/24] linux-headers: add unistd.h, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 17/24] vhost user: add rarp sending after live migration for legacy guest, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 20/24] vhost-user-test: wrap server in TestServer struct, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 02/24] configure: probe for memfd, marcandre . lureau, 2015/10/08
- [Qemu-devel] [PATCH v6 05/24] util: add memfd helpers, marcandre . lureau, 2015/10/08