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ArmPkg/ArmMmuLib ARM: Isolate the access flag from AP mask

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Split the ARM permission fields in the short descriptors into an access
flag and AP[2:1] as per the recommendation in the ARM ARM. This makes
the access flag available separately, which allows us to implement
EFI_MEMORY_RP memory analogous to how it will be implemented for
AArch64.

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 17:32:19 +01:00
committed by mergify[bot]
parent 699372d388
commit 28dce5b130
5 changed files with 63 additions and 39 deletions
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12
ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
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@@ -104,7 +104,7 @@ UpdatePageEntries (
// EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)
// EntryValue: values at bit positions specified by EntryMask
EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK | TT_DESCRIPTOR_PAGE_XN_MASK;
EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK | TT_DESCRIPTOR_PAGE_XN_MASK | TT_DESCRIPTOR_PAGE_AF;
EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE;
// Although the PI spec is unclear on this, the GCD guarantees that only
@@ -138,6 +138,10 @@ UpdatePageEntries (
return EFI_UNSUPPORTED;
}
if ((Attributes & EFI_MEMORY_RP) == 0) {
EntryValue |= TT_DESCRIPTOR_PAGE_AF;
}
if ((Attributes & EFI_MEMORY_RO) != 0) {
EntryValue |= TT_DESCRIPTOR_PAGE_AP_RO_RO;
} else {
@@ -237,7 +241,7 @@ UpdateSectionEntries (
// Make sure we handle a section range that is unmapped
EntryMask = TT_DESCRIPTOR_SECTION_TYPE_MASK | TT_DESCRIPTOR_SECTION_XN_MASK |
TT_DESCRIPTOR_SECTION_AP_MASK;
TT_DESCRIPTOR_SECTION_AP_MASK | TT_DESCRIPTOR_SECTION_AF;
EntryValue = TT_DESCRIPTOR_SECTION_TYPE_SECTION;
// Although the PI spec is unclear on this, the GCD guarantees that only
@@ -281,6 +285,10 @@ UpdateSectionEntries (
EntryValue |= TT_DESCRIPTOR_SECTION_XN_MASK;
}
if ((Attributes & EFI_MEMORY_RP) == 0) {
EntryValue |= TT_DESCRIPTOR_SECTION_AF;
}
// obtain page table base
FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();