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Commit 3ec3abcb authored by Will Deacon's avatar Will Deacon Committed by Greg Kroah-Hartman
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FROMLIST: arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 



Add a Kconfig entry to control use of the entry trampoline, which allows
us to unmap the kernel whilst running in userspace and improve the
robustness of KASLR.

Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Tested-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git


 commit 084eb77cd3a81134d02500977dc0ecc9277dc97d)

Change-Id: Iac41787b660dde902f32325afd2f454da600b60d
Signed-off-by: default avatarGreg Hackmann <ghackmann@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 2b4c5c1f

arch/arm64/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -527,6 +527,19 @@ config FORCE_MAX_ZONEORDER 
	default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)

	default "11"



config UNMAP_KERNEL_AT_EL0

	bool "Unmap kernel when running in userspace (aka \"KAISER\")"

	default y

	help

	  Some attacks against KASLR make use of the timing difference between

	  a permission fault which could arise from a page table entry that is

	  present in the TLB, and a translation fault which always requires a

	  page table walk. This option defends against these attacks by unmapping

	  the kernel whilst running in userspace, therefore forcing translation

	  faults for all of kernel space.



	  If unsure, say Y.



menuconfig ARMV8_DEPRECATED

	bool "Emulate deprecated/obsolete ARMv8 instructions"

	depends on COMPAT