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ArmPkg/ArmMmuLib: Implement EFI_MEMORY_RP using access flag

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Implement support for read-protected memory by wiring it up to the
access flag in the page table descriptor. The resulting mapping is
implicitly non-writable and non-executable as well, but this is good
enough for implementing this attribute, as we never rely on write or
execute permissions without read permissions.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
This commit is contained in:
Ard Biesheuvel
2023-02-07 16:09:56 +01:00
committed by mergify[bot]
parent 041c7a31c2
commit 6b821be140
4 changed files with 144 additions and 4 deletions
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8
ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
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@@ -64,6 +64,10 @@ PageAttributeToGcdAttribute (
}
// Determine protection attributes
if ((PageAttributes & TT_AF) == 0) {
GcdAttributes |= EFI_MEMORY_RP;
}
if (((PageAttributes & TT_AP_MASK) == TT_AP_NO_RO) ||
((PageAttributes & TT_AP_MASK) == TT_AP_RO_RO))
{
@@ -301,7 +305,9 @@ EfiAttributeToArmAttribute (
}
// Set the access flag to match the block attributes
ArmAttributes |= TT_AF;
if ((EfiAttributes & EFI_MEMORY_RP) == 0) {
ArmAttributes |= TT_AF;
}
// Determine protection attributes
if ((EfiAttributes & EFI_MEMORY_RO) != 0) {