From d8d23fa0f27f3b2942a7bbc7378c7735324ed519 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 20 Aug 2015 11:47:13 +0100 Subject: [PATCH] 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 --- arch/arm64/mm/proc.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 6e8765a2bddd..e4ee7bd8830a 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -151,7 +151,8 @@ 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: * -- 2.45.2