arm64/mm: use fixmap to modify swapper_pg_dir

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Once swapper_pg_dir is in the rodata section, it will not be possible to
modify it directly, but we will need to modify it in some cases.

To enable this, we can use the fixmap when deliberately modifying
swapper_pg_dir. As the pgd is only transiently mapped, this provides
some resilience against illicit modification of the pgd, e.g. for
Kernel Space Mirror Attack (KSMA).

Signed-off-by: Jun Yao <yaojun8558363@gmail.com>
Reviewed-by: James Morse <james.morse@arm.com>
[Mark: simplify ifdeffery, commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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Jun Yao 2018-09-24 17:15:02 +01:00 • committed by Catalin Marinas

parent 2b5548b681

commit 2330b7ca78

2 changed files with 53 additions and 8 deletions

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35

arch/arm64/include/asm/pgtable.h

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26

arch/arm64/mm/mmu.c

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