Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 039/268] arm64: mdscr_el1: avoid exposing DCC to userspace | Date | Wed, 27 Jan 2016 12:31:40 -0800 |
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4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon <will.deacon@arm.com>
commit d8d23fa0f27f3b2942a7bbc7378c7735324ed519 upstream.
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> [ kamal: 4.2-stable prereq for 60792ad arm64: kernel: enforce pmuserenr_el0 initialization and restore ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- 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 39139a3..f28a1fe 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -156,7 +156,8 @@ 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: * -- 1.9.1
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