mm: export stable page flags

Rename get_uflags() to stable_page_flags() and make it a global function
for use in the hwpoison page flags filter, which need to compare user
page flags with the value provided by user space.

Also move KPF_* to kernel-page-flags.h for use by user space tools.

Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
CC: Nick Piggin <npiggin@suse.de>
CC: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

3 files changed, 51 insertions, 42 deletions

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 5033ce0d254b..180cf5a0bd67 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -8,6 +8,7 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/hugetlb.h>
+#include <linux/kernel-page-flags.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -71,52 +72,12 @@ static const struct file_operations proc_kpagecount_operations = {
  * physical page flags.
  */
 
-/* These macros are used to decouple internal flags from exported ones */
-
-#define KPF_LOCKED              0
-#define KPF_ERROR               1
-#define KPF_REFERENCED          2
-#define KPF_UPTODATE            3
-#define KPF_DIRTY               4
-#define KPF_LRU                 5
-#define KPF_ACTIVE              6
-#define KPF_SLAB                7
-#define KPF_WRITEBACK           8
-#define KPF_RECLAIM             9
-#define KPF_BUDDY               10
-
-/* 11-20: new additions in 2.6.31 */
-#define KPF_MMAP                11
-#define KPF_ANON                12
-#define KPF_SWAPCACHE           13
-#define KPF_SWAPBACKED          14
-#define KPF_COMPOUND_HEAD       15
-#define KPF_COMPOUND_TAIL       16
-#define KPF_HUGE                17
-#define KPF_UNEVICTABLE         18
-#define KPF_HWPOISON            19
-#define KPF_NOPAGE              20
-
-#define KPF_KSM                 21
-
-/* kernel hacking assistances
- * WARNING: subject to change, never rely on them!
- */
-#define KPF_RESERVED            32
-#define KPF_MLOCKED             33
-#define KPF_MAPPEDTODISK        34
-#define KPF_PRIVATE             35
-#define KPF_PRIVATE_2           36
-#define KPF_OWNER_PRIVATE       37
-#define KPF_ARCH                38
-#define KPF_UNCACHED            39
-
 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
 {
         return ((kflags >> kbit) & 1) << ubit;
 }
 
-static u64 get_uflags(struct page *page)
+u64 stable_page_flags(struct page *page)
 {
         u64 k;
         u64 u;
@@ -219,7 +180,7 @@ static ssize_t kpageflags_read(struct file *file, char __user *buf,
                 else
                         ppage = NULL;
 
-                if (put_user(get_uflags(ppage), out)) {
+                if (put_user(stable_page_flags(ppage), out)) {
                         ret = -EFAULT;
                         break;
                 }
diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h
new file mode 100644
index 000000000000..bd92a89f4b0a
--- /dev/null
+++ b/include/linux/kernel-page-flags.h
@@ -0,0 +1,46 @@
+#ifndef LINUX_KERNEL_PAGE_FLAGS_H
+#define LINUX_KERNEL_PAGE_FLAGS_H
+
+/*
+ * Stable page flag bits exported to user space
+ */
+
+#define KPF_LOCKED              0
+#define KPF_ERROR               1
+#define KPF_REFERENCED          2
+#define KPF_UPTODATE            3
+#define KPF_DIRTY               4
+#define KPF_LRU                 5
+#define KPF_ACTIVE              6
+#define KPF_SLAB                7
+#define KPF_WRITEBACK           8
+#define KPF_RECLAIM             9
+#define KPF_BUDDY               10
+
+/* 11-20: new additions in 2.6.31 */
+#define KPF_MMAP                11
+#define KPF_ANON                12
+#define KPF_SWAPCACHE           13
+#define KPF_SWAPBACKED          14
+#define KPF_COMPOUND_HEAD       15
+#define KPF_COMPOUND_TAIL       16
+#define KPF_HUGE                17
+#define KPF_UNEVICTABLE         18
+#define KPF_HWPOISON            19
+#define KPF_NOPAGE              20
+
+#define KPF_KSM                 21
+
+/* kernel hacking assistances
+ * WARNING: subject to change, never rely on them!
+ */
+#define KPF_RESERVED            32
+#define KPF_MLOCKED             33
+#define KPF_MAPPEDTODISK        34
+#define KPF_PRIVATE             35
+#define KPF_PRIVATE_2           36
+#define KPF_OWNER_PRIVATE       37
+#define KPF_ARCH                38
+#define KPF_UNCACHED            39
+
+#endif /* LINUX_KERNEL_PAGE_FLAGS_H */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index f9df6308af95..feee2ba8d06a 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -282,6 +282,8 @@ PAGEFLAG_FALSE(HWPoison)
 #define __PG_HWPOISON 0
 #endif
 
+u64 stable_page_flags(struct page *page);
+
 static inline int PageUptodate(struct page *page)
 {
         int ret = test_bit(PG_uptodate, &(page)->flags);