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arm64: Add missing ISB after invalidating TLB in __primary_switch 

[ Upstream commit 9d41053e8dc115c92b8002c3db5f545d7602498b ]

Although there has been a bit of back and forth on the subject, it
appears that invalidating TLBs requires an ISB instruction when FEAT_ETS
is not implemented by the CPU.

From the bible:

  | In an implementation that does not implement FEAT_ETS, a TLB
  | maintenance instruction executed by a PE, PEx, can complete at any
  | time after it is issued, but is only guaranteed to be finished for a
  | PE, PEx, after the execution of DSB by the PEx followed by a Context
  | synchronization event

Add the missing ISB in __primary_switch, just in case.

Fixes: 3c5e9f238b ("arm64: head.S: move KASLR processing out of __enable_mmu()")
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210224093738.3629662-3-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Marc Zyngier 2021-02-24 09:37:37 +00:00 committed by Greg Kroah-Hartman
parent 94a432151c
commit 1a47856548
1 changed files with 1 additions and 0 deletions
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arch/arm64/kernel/head.S
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@ -970,6 +970,7 @@ __primary_switch:
tlbi vmalle1 // Remove any stale TLB entries
dsb nsh
isb
msr sctlr_el1, x19 // re-enable the MMU
isb