From 6c862bd05922af770c5b652037404c4f8131d984 Mon Sep 17 00:00:00 2001
From: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Thu, 28 Apr 2022 23:16:12 -0700
Subject: [PATCH] mm/mmap: clarify protection_map[] indices
References: jsc#PED-1981
Patch-mainline: v5.19-rc1
Git-commit: 6c862bd05922af770c5b652037404c4f8131d984
protection_map[] maps vm_flags access combinations into page protection
value as defined by the platform via __PXXX and __SXXX macros. The array
indices in protection_map[], represents vm_flags access combinations but
it's not very intuitive to derive. This makes it clear and explicit.
Link: https://lkml.kernel.org/r/20220404031840.588321-3-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
mm/mmap.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 042f01ec02fe..7873cc3ca24c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -102,8 +102,22 @@ static void unmap_region(struct mm_struct *mm,
* x: (yes) yes
*/
pgprot_t protection_map[16] __ro_after_init = {
- __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
- __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
+ [VM_NONE] = __P000,
+ [VM_READ] = __P001,
+ [VM_WRITE] = __P010,
+ [VM_WRITE | VM_READ] = __P011,
+ [VM_EXEC] = __P100,
+ [VM_EXEC | VM_READ] = __P101,
+ [VM_EXEC | VM_WRITE] = __P110,
+ [VM_EXEC | VM_WRITE | VM_READ] = __P111,
+ [VM_SHARED] = __S000,
+ [VM_SHARED | VM_READ] = __S001,
+ [VM_SHARED | VM_WRITE] = __S010,
+ [VM_SHARED | VM_WRITE | VM_READ] = __S011,
+ [VM_SHARED | VM_EXEC] = __S100,
+ [VM_SHARED | VM_EXEC | VM_READ] = __S101,
+ [VM_SHARED | VM_EXEC | VM_WRITE] = __S110,
+ [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = __S111
};
#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
--
2.35.3