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mm/mmap: clarify protection_map[] indices

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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>
This commit is contained in:
Anshuman Khandual 2022-04-28 23:16:12 -07:00 committed by akpm
parent 31d17076b0
commit 6c862bd059
1 changed files with 16 additions and 2 deletions
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18
mm/mmap.c
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@ -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