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-rw-r--r--util/Makefile.objs13
-rw-r--r--util/memfd.c162
-rw-r--r--util/mmap-alloc.c71
-rw-r--r--util/oslib-posix.c28
4 files changed, 247 insertions, 27 deletions
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 1363d1fce8..d7cc39907f 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -1,13 +1,20 @@
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-$(CONFIG_POSIX) += compatfd.o
+util-obj-$(CONFIG_POSIX) += event_notifier-posix.o
+util-obj-$(CONFIG_POSIX) += mmap-alloc.o
+util-obj-$(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
util-obj-$(call lnot,$(CONFIG_INT128)) += host-utils.o
util-obj-y += bitmap.o bitops.o hbitmap.o
util-obj-y += fifo8.o
util-obj-y += acl.o
util-obj-y += error.o qemu-error.o
-util-obj-$(CONFIG_POSIX) += compatfd.o
util-obj-y += id.o
util-obj-y += iov.o qemu-config.o qemu-sockets.o uri.o notify.o
util-obj-y += qemu-option.o qemu-progress.o
diff --git a/util/memfd.c b/util/memfd.c
new file mode 100644
index 0000000000..7c406914c5
--- /dev/null
+++ b/util/memfd.c
@@ -0,0 +1,162 @@
+/*
+ * 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 <glib.h>
+#include <glib/gprintf.h>
+
+#include <sys/mman.h>
+
+#include "qemu/memfd.h"
+
+#ifdef CONFIG_MEMFD
+#include <sys/memfd.h>
+#elif defined CONFIG_LINUX
+#include <sys/syscall.h>
+#include <asm/unistd.h>
+
+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
+
+/*
+ * This is a best-effort helper for shared memory allocation, with
+ * optional sealing. The helper will do his best to allocate using
+ * memfd with sealing, but may fallback on other methods without
+ * sealing.
+ */
+void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals,
+ int *fd)
+{
+ void *ptr;
+ int mfd = -1;
+
+ *fd = -1;
+
+#ifdef CONFIG_LINUX
+ if (seals) {
+ mfd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
+ }
+
+ if (mfd == -1) {
+ /* some systems have memfd without sealing */
+ mfd = memfd_create(name, MFD_CLOEXEC);
+ seals = 0;
+ }
+#endif
+
+ if (mfd != -1) {
+ if (ftruncate(mfd, size) == -1) {
+ perror("ftruncate");
+ close(mfd);
+ return NULL;
+ }
+
+ if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
+ perror("fcntl");
+ close(mfd);
+ return NULL;
+ }
+ } else {
+ const char *tmpdir = g_get_tmp_dir();
+ gchar *fname;
+
+ fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir);
+ mfd = mkstemp(fname);
+ unlink(fname);
+ g_free(fname);
+
+ if (mfd == -1) {
+ perror("mkstemp");
+ return NULL;
+ }
+
+ if (ftruncate(mfd, size) == -1) {
+ perror("ftruncate");
+ close(mfd);
+ return NULL;
+ }
+ }
+
+ ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0);
+ if (ptr == MAP_FAILED) {
+ perror("mmap");
+ close(mfd);
+ return NULL;
+ }
+
+ *fd = mfd;
+ return ptr;
+}
+
+void qemu_memfd_free(void *ptr, size_t size, int fd)
+{
+ if (ptr) {
+ munmap(ptr, size);
+ }
+
+ if (fd != -1) {
+ close(fd);
+ }
+}
+
+enum {
+ MEMFD_KO,
+ MEMFD_OK,
+ MEMFD_TODO
+};
+
+bool qemu_memfd_check(void)
+{
+ static int memfd_check = MEMFD_TODO;
+
+ if (memfd_check == MEMFD_TODO) {
+ int fd;
+ void *ptr;
+
+ ptr = qemu_memfd_alloc("test", 4096, 0, &fd);
+ memfd_check = ptr ? MEMFD_OK : MEMFD_KO;
+ qemu_memfd_free(ptr, 4096, fd);
+ }
+
+ return memfd_check == MEMFD_OK;
+}
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
new file mode 100644
index 0000000000..13942694cc
--- /dev/null
+++ b/util/mmap-alloc.c
@@ -0,0 +1,71 @@
+/*
+ * Support for RAM backed by mmaped host memory.
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * Authors:
+ * Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ */
+#include <qemu/mmap-alloc.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <assert.h>
+
+void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
+{
+ /*
+ * Note: this always allocates at least one extra page of virtual address
+ * space, even if size is already aligned.
+ */
+ size_t total = size + align;
+ void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
+ void *ptr1;
+
+ if (ptr == MAP_FAILED) {
+ return NULL;
+ }
+
+ /* Make sure align is a power of 2 */
+ assert(!(align & (align - 1)));
+ /* Always align to host page size */
+ assert(align >= getpagesize());
+
+ ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
+ MAP_FIXED |
+ (fd == -1 ? MAP_ANONYMOUS : 0) |
+ (shared ? MAP_SHARED : MAP_PRIVATE),
+ fd, 0);
+ if (ptr1 == MAP_FAILED) {
+ munmap(ptr, total);
+ return NULL;
+ }
+
+ ptr += offset;
+ total -= offset;
+
+ if (offset > 0) {
+ munmap(ptr - offset, offset);
+ }
+
+ /*
+ * Leave a single PROT_NONE page allocated after the RAM block, to serve as
+ * a guard page guarding against potential buffer overflows.
+ */
+ if (total > size + getpagesize()) {
+ munmap(ptr + size + getpagesize(), total - size - getpagesize());
+ }
+
+ return ptr;
+}
+
+void qemu_ram_munmap(void *ptr, size_t size)
+{
+ if (ptr) {
+ /* Unmap both the RAM block and the guard page */
+ munmap(ptr, size + getpagesize());
+ }
+}
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 40249183e6..914cef5c2c 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -72,6 +72,8 @@ extern int daemon(int, int);
#include <sys/sysctl.h>
#endif
+#include <qemu/mmap-alloc.h>
+
int qemu_get_thread_id(void)
{
#if defined(__linux__)
@@ -128,10 +130,7 @@ void *qemu_memalign(size_t alignment, size_t size)
void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
{
size_t align = QEMU_VMALLOC_ALIGN;
- size_t total = size + align;
- void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
- size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
- void *ptr1;
+ void *ptr = qemu_ram_mmap(-1, size, align, false);
if (ptr == MAP_FAILED) {
return NULL;
@@ -141,23 +140,6 @@ void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
*alignment = align;
}
- ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
- if (ptr1 == MAP_FAILED) {
- munmap(ptr, total);
- return NULL;
- }
-
- ptr += offset;
- total -= offset;
-
- if (offset > 0) {
- munmap(ptr - offset, offset);
- }
- if (total > size + getpagesize()) {
- munmap(ptr + size + getpagesize(), total - size - getpagesize());
- }
-
trace_qemu_anon_ram_alloc(size, ptr);
return ptr;
}
@@ -171,9 +153,7 @@ void qemu_vfree(void *ptr)
void qemu_anon_ram_free(void *ptr, size_t size)
{
trace_qemu_anon_ram_free(ptr, size);
- if (ptr) {
- munmap(ptr, size + getpagesize());
- }
+ qemu_ram_munmap(ptr, size);
}
void qemu_set_block(int fd)
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-18 06:53:34 +0000