Commit 6c862bd0 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Andrew Morton
Browse files

mm/mmap: clarify protection_map[] indices 

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: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 31d17076

mm/mmap.c

+16 −2
Original line number Diff line number Diff line
@@ -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