Commit 6079041f authored Aug 20, 2015 by Will Deacon Committed by Sami Tolvanen Nov 22, 2016

UPSTREAM: 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>

Bug: 31432001
Change-Id: I0d2ac193d444a017cd1dbe234a8ead8572abdf87
(cherry picked from commit d8d23fa0f27f3b2942a7bbc7378c7735324ed519)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

parent 82d34266

arch/arm64/mm/proc.S

+2 −1

Original line number	Diff line number	Diff line
		@@ -196,7 +196,8 @@ ENTRY(__cpu_setup)

		mov x0, #3 << 20
		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:
		*