Patch "arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-avoid-tlb-conflict-with-config_randomize_base.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mark Rutland <[email protected]>
Date: Wed, 24 Aug 2016 18:02:08 +0100
Subject: arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE

From: Mark Rutland <[email protected]>

commit fd363bd417ddb6103564c69cfcbd92d9a7877431 upstream.

When CONFIG_RANDOMIZE_BASE is selected, we modify the page tables to remap the kernel at a newly-chosen VA range. We do this with the MMU disabled, but do not invalidate TLBs prior to re-enabling the MMU with the new tables. Thus the old mappings entries may still live in TLBs, and we risk violating Break-Before-Make requirements, leading to TLB conflicts and/or other issues.

We invalidate TLBs when we uninsall the idmap in early setup code, but prior to this we are subject to issues relating to the Break-Before-Make violation.

Avoid these issues by invalidating the TLBs before the new mappings can be used by the hardware.

---
 arch/arm64/kernel/head.S |    3 +++
 1 file changed, 3 insertions(+)

@@ -757,6 +757,9 @@ ENTRY(__enable_mmu)
 	isb
 	bl	__create_page_tables		// recreate kernel mapping
 
+	tlbi	vmalle1				// Remove any stale TLB entries
+	dsb	nsh
+
 	msr	sctlr_el1, x19			// re-enable the MMU
 	isb
 	ic	iallu				// flush instructions fetched

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/arm64-kernel-avoid-literal-load-of-virtual-address-with-mmu-off.patch queue-4.7/arm64-avoid-tlb-conflict-with-config_randomize_base.patch