arm64: mm: move vmemmap region right below the linear region

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This moves the vmemmap region right below PAGE_OFFSET, aka the start
of the linear region, and redefines its size to be a power of two.
Due to the placement of PAGE_OFFSET in the middle of the address space,
whose size is a power of two as well, this guarantees that virt to
page conversions and vice versa can be implemented efficiently, by
masking and shifting rather than ordinary arithmetic.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

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Ard Biesheuvel 2016-03-30 16:46:00 +02:00 • committed by Will Deacon

parent e44308e62e

commit 3e1907d5bf

4 changed files with 38 additions and 21 deletions

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18

arch/arm64/include/asm/memory.h

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11

arch/arm64/include/asm/pgtable.h

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16

arch/arm64/mm/dump.c

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14

arch/arm64/mm/init.c

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