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 9890d04a96cb8a4eeeef14f392ded2f92a0311ad..488708687fdad1765abad99cf32e91c6b4dbf415 100644 (file)
--- 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