ArmPkg/AArch64Mmu: use correct AP[] bits in ArmClearMemoryRegionReadOnly

The function ArmClearMemoryRegionReadOnly() was supposed to undo the
effect of ArmSetMemoryRegionReadOnly(), but instead, it sets the permissions
to EL0-no access, EL1-read-only. Since the EL0 bit should be 1 to align
with EL2/3 (where the bit is SBO), use TT_AP_RW_RW instead, which makes the
entry read-write for EL0 when executing at EL1, and read-write for all other
levels.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
index f967a64788..b7d23c6f32 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
@@ -558,7 +558,7 @@ ArmClearMemoryRegionReadOnly (
   return SetMemoryRegionAttribute (

            BaseAddress,

            Length,

-           TT_AP_NO_RO,

+           TT_AP_RW_RW,

            ~(TT_ADDRESS_MASK_BLOCK_ENTRY | TT_AP_MASK));

 }