arm64: mdscr_el1: avoid exposing DCC to userspace



We don't want to expose the DCC to userspace, particularly as there is
a kernel console driver for it.

This patch resets mdscr_el1 to disable userspace access to the DCC
registers on the cold boot path.

Signed-off-by: Will Deacon <will.deacon@arm.com>

parent bf0c4e04

arch/arm64/mm/proc.S

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -151,7 +151,8 @@ ENTRY(__cpu_setup)

	mov x0, #3 << 20		mov x0, #3 << 20
	msr cpacr_el1, x0 // Enable FP/ASIMD		msr cpacr_el1, x0 // Enable FP/ASIMD
	msr mdscr_el1, xzr // Reset mdscr_el1		mov x0, #1 << 12 // Reset mdscr_el1 and disable
			msr mdscr_el1, x0 // access to the DCC from EL0
	/*		/*
	* Memory region attributes for LPAE:		* Memory region attributes for LPAE:
	*		*