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[PATCH v4 07/15] util/mmap-alloc: Factor out calculation of the pagesize
From: |
David Hildenbrand |
Subject: |
[PATCH v4 07/15] util/mmap-alloc: Factor out calculation of the pagesize for the guard page |
Date: |
Thu, 5 Mar 2020 15:29:37 +0100 |
Let's factor out calculating the size of the guard page and rename the
variable to make it clearer that this pagesize only applies to the
guard page.
Reviewed-by: Peter Xu <address@hidden>
Cc: "Michael S. Tsirkin" <address@hidden>
Cc: Murilo Opsfelder Araujo <address@hidden>
Cc: Greg Kurz <address@hidden>
Cc: Eduardo Habkost <address@hidden>
Cc: "Dr. David Alan Gilbert" <address@hidden>
Cc: Igor Mammedov <address@hidden>
Signed-off-by: David Hildenbrand <address@hidden>
---
util/mmap-alloc.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 27dcccd8ec..f0277f9fad 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -82,17 +82,27 @@ size_t qemu_mempath_getpagesize(const char *mem_path)
return qemu_real_host_page_size;
}
+static inline size_t mmap_guard_pagesize(int fd)
+{
+#if defined(__powerpc64__) && defined(__linux__)
+ /* Mappings in the same segment must share the same page size */
+ return qemu_fd_getpagesize(fd);
+#else
+ return qemu_real_host_page_size;
+#endif
+}
+
void *qemu_ram_mmap(int fd,
size_t size,
size_t align,
bool shared,
bool is_pmem)
{
+ const size_t guard_pagesize = mmap_guard_pagesize(fd);
int flags;
int map_sync_flags = 0;
int guardfd;
size_t offset;
- size_t pagesize;
size_t total;
void *guardptr;
void *ptr;
@@ -113,8 +123,7 @@ void *qemu_ram_mmap(int fd,
* anonymous memory is OK.
*/
flags = MAP_PRIVATE;
- pagesize = qemu_fd_getpagesize(fd);
- if (fd == -1 || pagesize == qemu_real_host_page_size) {
+ if (fd == -1 || guard_pagesize == qemu_real_host_page_size) {
guardfd = -1;
flags |= MAP_ANONYMOUS;
} else {
@@ -123,7 +132,6 @@ void *qemu_ram_mmap(int fd,
}
#else
guardfd = -1;
- pagesize = qemu_real_host_page_size;
flags = MAP_PRIVATE | MAP_ANONYMOUS;
#endif
@@ -135,7 +143,7 @@ void *qemu_ram_mmap(int fd,
assert(is_power_of_2(align));
/* Always align to host page size */
- assert(align >= pagesize);
+ assert(align >= guard_pagesize);
flags = MAP_FIXED;
flags |= fd == -1 ? MAP_ANONYMOUS : 0;
@@ -189,8 +197,8 @@ void *qemu_ram_mmap(int fd,
* a guard page guarding against potential buffer overflows.
*/
total -= offset;
- if (total > size + pagesize) {
- munmap(ptr + size + pagesize, total - size - pagesize);
+ if (total > size + guard_pagesize) {
+ munmap(ptr + size + guard_pagesize, total - size - guard_pagesize);
}
return ptr;
@@ -198,15 +206,8 @@ void *qemu_ram_mmap(int fd,
void qemu_ram_munmap(int fd, void *ptr, size_t size)
{
- size_t pagesize;
-
if (ptr) {
/* Unmap both the RAM block and the guard page */
-#if defined(__powerpc64__) && defined(__linux__)
- pagesize = qemu_fd_getpagesize(fd);
-#else
- pagesize = qemu_real_host_page_size;
-#endif
- munmap(ptr, size + pagesize);
+ munmap(ptr, size + mmap_guard_pagesize(fd));
}
}
--
2.24.1
- Re: [PATCH v4 03/15] util: vfio-helpers: Factor out removal from qemu_vfio_undo_mapping(), (continued)
- [PATCH v4 05/15] exec: Reuse qemu_ram_apply_settings() in qemu_ram_remap(), David Hildenbrand, 2020/03/05
- [PATCH v4 04/15] exec: Factor out setting ram settings (madvise ...) into qemu_ram_apply_settings(), David Hildenbrand, 2020/03/05
- [PATCH v4 08/15] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve(), David Hildenbrand, 2020/03/05
- [PATCH v4 06/15] exec: Drop "shared" parameter from ram_block_add(), David Hildenbrand, 2020/03/05
- [PATCH v4 09/15] util/mmap-alloc: Factor out activating of memory to mmap_activate(), David Hildenbrand, 2020/03/05
- [PATCH v4 10/15] util/mmap-alloc: Prepare for resizeable mmaps, David Hildenbrand, 2020/03/05
- [PATCH v4 11/15] util/mmap-alloc: Implement resizeable mmaps, David Hildenbrand, 2020/03/05
- [PATCH v4 07/15] util/mmap-alloc: Factor out calculation of the pagesize for the guard page,
David Hildenbrand <=
- [PATCH v4 13/15] util: oslib: Resizeable anonymous allocations under POSIX, David Hildenbrand, 2020/03/05
- [PATCH v4 12/15] util: vfio-helpers: Implement ram_block_resized(), David Hildenbrand, 2020/03/05
- [PATCH v4 14/15] numa: Introduce ram_block_notifiers_support_resize(), David Hildenbrand, 2020/03/05
- [PATCH v4 15/15] exec: Ram blocks with resizeable anonymous allocations under POSIX, David Hildenbrand, 2020/03/05