arm64: kdump: protect crash dump kernel memory

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arch_kexec_protect_crashkres() and arch_kexec_unprotect_crashkres()
are meant to be called by kexec_load() in order to protect the memory
allocated for crash dump kernel once the image is loaded.

The protection is implemented by unmapping the relevant segments in crash
dump kernel memory, rather than making it read-only as other archs do,
to prevent coherency issues due to potential cache aliasing (with
mismatched attributes).

Page-level mappings are consistently used here so that we can change
the attributes of segments in page granularity as well as shrink the region
also in page granularity through /sys/kernel/kexec_crash_size, putting
the freed memory back to buddy system.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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This commit is contained in:

Takahiro Akashi 2017-04-03 11:24:34 +09:00 • committed by Catalin Marinas

parent 9b0aa14e31

commit 98d2e1539b

2 changed files with 80 additions and 55 deletions

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32

arch/arm64/kernel/machine_kexec.c

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105

arch/arm64/mm/mmu.c

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