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Subject[PATCH 5.4 231/340] arm64: Add missing ISB after invalidating TLB in __primary_switch
Date
From: Marc Zyngier <maz@kernel.org>

[ 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: 3c5e9f238bc4 ("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>
---
arch/arm64/kernel/head.S | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index bdb5ec3419006..438de2301cfe3 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -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
--
2.27.0


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