From: Mark Rutland <mark.rutland@arm.com>
Date: Wed, 24 Aug 2016 17:02:08 +0000 (+0100)
Subject: UPSTREAM: arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE
X-Git-Tag: firefly_0821_release~176^2~159
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=firefly-linux-kernel-4.4.55.git;a=commitdiff_plain;h=feffbe70d5610268474c76f429fa9dc4e9696d70

UPSTREAM: arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE

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.

Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR")
Cc: <stable@vger.kernel.org> # 4.6+
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 30369029
Patchset: kaslr-arm64-4.4

(cherry picked from commit fd363bd417ddb6103564c69cfcbd92d9a7877431)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I6c23ce55cdd8b66587b6787b8f28df8535e39f24
---

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 9890d04a96cb..488708687fda 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -697,6 +697,9 @@ __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