Memory protection keys (pkeys) uapi has two macros for pkeys restrictions:
- PKEY_DISABLE_ACCESS 0x1 - PKEY_DISABLE_WRITE 0x2
with implicit literal value of 0x0 that means "unrestricted". Code that works with pkeys has to use this literal value when implying that a pkey imposes no restrictions. This may reduce readability because 0 can be written in various ways (e.g. 0x0 or 0) and also because 0 in the context of pkeys can be mistaken for "no permissions" (akin PROT_NONE) while it actually means "no restrictions". This is important because pkeys are oftentimes used near mprotect() that uses PROT_ macros.
This patch adds PKEY_UNRESTRICTED macro defined as 0x0.
Signed-off-by: Yury Khrustalev yury.khrustalev@arm.com Acked-by: Dave Hansen dave.hansen@linux.intel.com --- include/uapi/asm-generic/mman-common.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index 1ea2c4c33b86..ef1c27fa3c57 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -85,6 +85,7 @@ /* compatibility flags */ #define MAP_FILE 0
+#define PKEY_UNRESTRICTED 0x0 #define PKEY_DISABLE_ACCESS 0x1 #define PKEY_DISABLE_WRITE 0x2 #define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS |\