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UPSTREAM: arm64: avoid TLB conflict with CONFIG_RANDOMIZE_BASE

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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: f80fb3a3d5 ("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 fd363bd417)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I6c23ce55cdd8b66587b6787b8f28df8535e39f24
This commit is contained in:
Mark Rutland
2016-08-24 18:02:08 +01:00
committed by Jeff Vander Stoep
parent 42f010ac16
commit 1488d59cb5
1 changed files with 3 additions and 0 deletions
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3
arch/arm64/kernel/head.S
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@@ -738,6 +738,9 @@ __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