Even with MMU turned off, instruction cache can speculate
and fetch instructions. This can cause a crash if region
being executed has been modified recently. With this patch,
we ensure that instruction cache is invalidated right after
MMU has been enabled and any potentially stale instruction
fetched earlier has been discarded.
This is specially helpful when the memory attributes of a
region in MMU are being changed and some instructions
operating on the region are prefetched in the instruction
cache.
Signed-off-by: Ashish Singhal <ashishsin...@nvidia.com>
---
ArmPkg/Library/ArmLib/AArch64/AArch64Support.S | 4 +++-
ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S | 2 ++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
index d3cc1e8671..047192ec91 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
@@ -89,7 +89,9 @@ ASM_FUNC(ArmEnableMmu)
dsb nsh
isb
msr sctlr_el3, x0 // Write back
-4: isb
+4: ic iallu
+ dsb nsh
+ isb
ret
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
index 66ebca571e..4fe75ec841 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S
@@ -37,6 +37,8 @@
// re-enable the MMU
msr sctlr_el\el, x8
+ ic iallu
+ dsb nsh
isb
.endm
--
2.17.1
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