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Commit ce3aaed8 authored by Steve Capper's avatar Steve Capper Committed by Will Deacon
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arm64: mm: Modify calculation of VMEMMAP_SIZE 



In a later patch we will need to have a slightly larger VMEMMAP region
to accommodate boot time selection between 48/52-bit kernel VAs.

This patch modifies the formula for computing VMEMMAP_SIZE to depend
explicitly on the PAGE_OFFSET and start of kernel addressable memory.
(This allows for a slightly larger direct linear map in future).

Signed-off-by: default avatarSteve Capper <steve.capper@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent c8b6d2cc

arch/arm64/include/asm/memory.h

+8 −1
Original line number Diff line number Diff line
@@ -26,8 +26,15 @@ 
/*

 * VMEMMAP_SIZE - allows the whole linear region to be covered by

 *                a struct page array

 *

 * If we are configured with a 52-bit kernel VA then our VMEMMAP_SIZE

 * neads to cover the memory region from the beginning of the 52-bit

 * PAGE_OFFSET all the way to VA_START for 48-bit. This allows us to

 * keep a constant PAGE_OFFSET and "fallback" to using the higher end

 * of the VMEMMAP where 52-bit support is not available in hardware.

 */

#define VMEMMAP_SIZE (UL(1) << (VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT))

#define VMEMMAP_SIZE ((_VA_START(VA_BITS_MIN) - PAGE_OFFSET) \

			>> (PAGE_SHIFT - STRUCT_PAGE_MAX_SHIFT))



/*

 * PAGE_OFFSET - the virtual address of the start of the linear map (top