* [Qemu-devel] [PATCH] exec: factor out duplicate mmap code
@ 2015-09-24 11:44 Michael S. Tsirkin
2015-09-24 11:49 ` Michael S. Tsirkin
0 siblings, 1 reply; 2+ messages in thread
From: Michael S. Tsirkin @ 2015-09-24 11:44 UTC (permalink / raw)
To: qemu-devel; +Cc: Paolo Bonzini, Peter Maydell
Anonymous and file-backed RAM allocation are now almost exactly the same.
Reduce code duplication by moving RAM mmap code out of oslib-posix.c and
exec.c.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
This is on top of the patchset:
add mitigation against buffer overflows
include/qemu/mmap-alloc.h | 10 +++++++++
exec.c | 38 +++++---------------------------
util/mmap-alloc.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
util/oslib-posix.c | 28 ++++--------------------
util/Makefile.objs | 2 +-
5 files changed, 77 insertions(+), 57 deletions(-)
create mode 100644 include/qemu/mmap-alloc.h
create mode 100644 util/mmap-alloc.c
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
new file mode 100644
index 0000000..3400e14
--- /dev/null
+++ b/include/qemu/mmap-alloc.h
@@ -0,0 +1,10 @@
+#ifndef QEMU_MMAP_ALLOC
+#define QEMU_MMAP_ALLOC
+
+#include "qemu-common.h"
+
+void *qemu_ram_mmap(int fd, size_t size, size_t align);
+
+void qemu_ram_munmap(void *ptr, size_t size);
+
+#endif
diff --git a/exec.c b/exec.c
index 7d90a52..dd8d40a 100644
--- a/exec.c
+++ b/exec.c
@@ -84,9 +84,9 @@ static MemoryRegion io_mem_unassigned;
*/
#define RAM_RESIZEABLE (1 << 2)
-/* An extra page is mapped on top of this RAM.
+/* RAM is backed by an mmapped file.
*/
-#define RAM_EXTRA (1 << 3)
+#define RAM_FILE (1 << 3)
#endif
struct CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus);
@@ -1250,40 +1250,14 @@ static void *file_ram_alloc(RAMBlock *block,
perror("ftruncate");
}
- ptr = mmap(0, total, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
- -1, 0);
- if (ptr == MAP_FAILED) {
- error_setg_errno(errp, errno,
- "unable to allocate memory range for hugepages");
- close(fd);
- goto error;
- }
-
- offset = QEMU_ALIGN_UP((uintptr_t)ptr, hpagesize) - (uintptr_t)ptr;
-
- area = mmap(ptr + offset, memory, PROT_READ | PROT_WRITE,
- (block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE) |
- MAP_FIXED,
- fd, 0);
+ area = qemu_ram_mmap(fd, memory, hpagesize);
if (area == MAP_FAILED) {
error_setg_errno(errp, errno,
"unable to map backing store for hugepages");
- munmap(ptr, total);
close(fd);
goto error;
}
- if (offset > 0) {
- munmap(ptr, offset);
- }
- ptr += offset;
- total -= offset;
-
- if (total > memory + getpagesize()) {
- munmap(ptr + memory + getpagesize(),
- total - memory - getpagesize());
- }
-
if (mem_prealloc) {
os_mem_prealloc(fd, area, memory);
}
@@ -1601,7 +1575,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
new_block->used_length = size;
new_block->max_length = size;
new_block->flags = share ? RAM_SHARED : 0;
- new_block->flags |= RAM_EXTRA;
+ new_block->flags |= RAM_FILE;
new_block->host = file_ram_alloc(new_block, size,
mem_path, errp);
if (!new_block->host) {
@@ -1703,8 +1677,8 @@ static void reclaim_ramblock(RAMBlock *block)
xen_invalidate_map_cache_entry(block->host);
#ifndef _WIN32
} else if (block->fd >= 0) {
- if (block->flags & RAM_EXTRA) {
- munmap(block->host, block->max_length + getpagesize());
+ if (block->flags & RAM_FILE) {
+ qemu_ram_munmap(block->host, block->max_length);
} else {
munmap(block->host, block->max_length);
}
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
new file mode 100644
index 0000000..6ea1f33
--- /dev/null
+++ b/util/mmap-alloc.c
@@ -0,0 +1,56 @@
+/*
+ * 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>
+
+void *qemu_ram_mmap(int fd, size_t size, size_t 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;
+
+ if (ptr == MAP_FAILED) {
+ return NULL;
+ }
+
+ if (alignment) {
+ *alignment = align;
+ }
+
+ ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
+ MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, fd, 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());
+ }
+
+ return ptr;
+}
+
+void qemu_ram_munmap(void *ptr)
+{
+ if (ptr) {
+ munmap(ptr, size + getpagesize());
+ }
+}
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index a0fcdc2..72a6bc1 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);
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)
diff --git a/util/Makefile.objs b/util/Makefile.objs
index 114d657..372e037 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-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o event_notifier-posix.o qemu-openpty.o mmap-alloc.o
util-obj-y += envlist.o path.o module.o
util-obj-$(call lnot,$(CONFIG_INT128)) += host-utils.o
util-obj-y += bitmap.o bitops.o hbitmap.o
--
MST
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] [PATCH] exec: factor out duplicate mmap code
2015-09-24 11:44 [Qemu-devel] [PATCH] exec: factor out duplicate mmap code Michael S. Tsirkin
@ 2015-09-24 11:49 ` Michael S. Tsirkin
0 siblings, 0 replies; 2+ messages in thread
From: Michael S. Tsirkin @ 2015-09-24 11:49 UTC (permalink / raw)
To: qemu-devel; +Cc: Paolo Bonzini, Peter Maydell
On Thu, Sep 24, 2015 at 02:44:41PM +0300, Michael S. Tsirkin wrote:
> Anonymous and file-backed RAM allocation are now almost exactly the same.
>
> Reduce code duplication by moving RAM mmap code out of oslib-posix.c and
> exec.c.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Och forgot to commit.
Wil send a fixed v2.
> ---
>
> This is on top of the patchset:
> add mitigation against buffer overflows
>
> include/qemu/mmap-alloc.h | 10 +++++++++
> exec.c | 38 +++++---------------------------
> util/mmap-alloc.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
> util/oslib-posix.c | 28 ++++--------------------
> util/Makefile.objs | 2 +-
> 5 files changed, 77 insertions(+), 57 deletions(-)
> create mode 100644 include/qemu/mmap-alloc.h
> create mode 100644 util/mmap-alloc.c
>
> diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
> new file mode 100644
> index 0000000..3400e14
> --- /dev/null
> +++ b/include/qemu/mmap-alloc.h
> @@ -0,0 +1,10 @@
> +#ifndef QEMU_MMAP_ALLOC
> +#define QEMU_MMAP_ALLOC
> +
> +#include "qemu-common.h"
> +
> +void *qemu_ram_mmap(int fd, size_t size, size_t align);
> +
> +void qemu_ram_munmap(void *ptr, size_t size);
> +
> +#endif
> diff --git a/exec.c b/exec.c
> index 7d90a52..dd8d40a 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -84,9 +84,9 @@ static MemoryRegion io_mem_unassigned;
> */
> #define RAM_RESIZEABLE (1 << 2)
>
> -/* An extra page is mapped on top of this RAM.
> +/* RAM is backed by an mmapped file.
> */
> -#define RAM_EXTRA (1 << 3)
> +#define RAM_FILE (1 << 3)
> #endif
>
> struct CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus);
> @@ -1250,40 +1250,14 @@ static void *file_ram_alloc(RAMBlock *block,
> perror("ftruncate");
> }
>
> - ptr = mmap(0, total, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
> - -1, 0);
> - if (ptr == MAP_FAILED) {
> - error_setg_errno(errp, errno,
> - "unable to allocate memory range for hugepages");
> - close(fd);
> - goto error;
> - }
> -
> - offset = QEMU_ALIGN_UP((uintptr_t)ptr, hpagesize) - (uintptr_t)ptr;
> -
> - area = mmap(ptr + offset, memory, PROT_READ | PROT_WRITE,
> - (block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE) |
> - MAP_FIXED,
> - fd, 0);
> + area = qemu_ram_mmap(fd, memory, hpagesize);
> if (area == MAP_FAILED) {
> error_setg_errno(errp, errno,
> "unable to map backing store for hugepages");
> - munmap(ptr, total);
> close(fd);
> goto error;
> }
>
> - if (offset > 0) {
> - munmap(ptr, offset);
> - }
> - ptr += offset;
> - total -= offset;
> -
> - if (total > memory + getpagesize()) {
> - munmap(ptr + memory + getpagesize(),
> - total - memory - getpagesize());
> - }
> -
> if (mem_prealloc) {
> os_mem_prealloc(fd, area, memory);
> }
> @@ -1601,7 +1575,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
> new_block->used_length = size;
> new_block->max_length = size;
> new_block->flags = share ? RAM_SHARED : 0;
> - new_block->flags |= RAM_EXTRA;
> + new_block->flags |= RAM_FILE;
> new_block->host = file_ram_alloc(new_block, size,
> mem_path, errp);
> if (!new_block->host) {
> @@ -1703,8 +1677,8 @@ static void reclaim_ramblock(RAMBlock *block)
> xen_invalidate_map_cache_entry(block->host);
> #ifndef _WIN32
> } else if (block->fd >= 0) {
> - if (block->flags & RAM_EXTRA) {
> - munmap(block->host, block->max_length + getpagesize());
> + if (block->flags & RAM_FILE) {
> + qemu_ram_munmap(block->host, block->max_length);
> } else {
> munmap(block->host, block->max_length);
> }
> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
> new file mode 100644
> index 0000000..6ea1f33
> --- /dev/null
> +++ b/util/mmap-alloc.c
> @@ -0,0 +1,56 @@
> +/*
> + * 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>
> +
> +void *qemu_ram_mmap(int fd, size_t size, size_t 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;
> +
> + if (ptr == MAP_FAILED) {
> + return NULL;
> + }
> +
> + if (alignment) {
> + *alignment = align;
> + }
> +
> + ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
> + MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, fd, 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());
> + }
> +
> + return ptr;
> +}
> +
> +void qemu_ram_munmap(void *ptr)
> +{
> + if (ptr) {
> + munmap(ptr, size + getpagesize());
> + }
> +}
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index a0fcdc2..72a6bc1 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);
>
> 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)
> diff --git a/util/Makefile.objs b/util/Makefile.objs
> index 114d657..372e037 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 mmap-alloc.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
> --
> MST
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-09-24 11:49 ` Michael S. Tsirkin
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