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: f80fb3a3d50843a4 ("arm64: add support for kernel ASLR")
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
arch/arm64/kernel/head.S | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index b77f583..3e7b050 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -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
--
2.7.4
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