arm64: mm: Move fixmap region above vmemmap region

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Move the fixmap region above the vmemmap region, so that the start of
the vmemmap delineates the end of the region available for vmalloc and
vmap allocations and the randomized placement of the kernel and modules.

In a subsequent patch, we will take advantage of this to reclaim most of
the vmemmap area when running a 52-bit VA capable build with 52-bit
virtual addressing disabled at runtime.

Note that the existing guard region of 256 MiB covers the fixmap and PCI
I/O regions as well, so we can reduce it 8 MiB, which is what we use in
other places too.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231213084024.2367360-11-ardb@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>

...

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Ard Biesheuvel 2023-12-13 09:40:27 +01:00 • committed by Catalin Marinas

parent 031e011d8b

commit b730b0f2b1

4 changed files with 7 additions and 4 deletions

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2

arch/arm64/include/asm/memory.h

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arch/arm64/include/asm/pgtable.h

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arch/arm64/mm/fixmap.c

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arch/arm64/mm/ptdump.c

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