arm64: mm: Map entry trampoline into trampoline and kernel page tables

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Commit 51a0048beb upstream.

The exception entry trampoline needs to be mapped at the same virtual
address in both the trampoline page table (which maps nothing else)
and also the kernel page table, so that we can swizzle TTBR1_EL1 on
exceptions from and return to EL0.

This patch maps the trampoline at a fixed virtual address in the fixmap
area of the kernel virtual address space, which allows the kernel proper
to be randomized with respect to the trampoline when KASLR is enabled.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Will Deacon 2017-11-14 14:14:17 +00:00 • committed by Greg Kroah-Hartman

parent a1f8eeab0e

commit 3f14b03dde

4 changed files with 33 additions and 1 deletions

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4

arch/arm64/include/asm/fixmap.h

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1

arch/arm64/include/asm/pgtable.h

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6

arch/arm64/kernel/asm-offsets.c

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23

arch/arm64/mm/mmu.c

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