HI Olivier,
ArmPkg\Drivers\CpuDxe\AArch64\Mmu.c has the code to find the memory type
programmed for the given region.
Equates are defined in AARch64mmu.h
#define TT_TYPE_MASK 0x3
#define TT_TYPE_TABLE_ENTRY 0x3
#define TT_TYPE_BLOCK_ENTRY 0x1
#define TT_TYPE_BLOCK_ENTRY_LEVEL3 0x3
In the below code, If level 3 table, Blockentrytype = 3. Since this entry
type satisfies (EntryType == TT_TYPE_TABLE_ENTRY) condition, It will try to
call the GetMemoryRegionRec() again instead . Do we need another condition
to make it reach the else part?
In other words, How to handle the situation (EntryType == TT_TYPE_TABLE_ENTRY)
= TRUE and (EntryType == BlockEntryType) = TRUE
Thanks
Siva
ArmPkg\Drivers\CpuDxe\AArch64\Mmu.c code snippet
if (TableLevel != 3) {
BlockEntryType = TT_TYPE_BLOCK_ENTRY;
} else {
BlockEntryType = TT_TYPE_BLOCK_ENTRY_LEVEL3;
}
// Find the block entry linked to the Base Address
BlockEntry = (UINT64*)TT_GET_ENTRY_FOR_ADDRESS (TranslationTable, TableLevel,
*BaseAddress);
EntryType = *BlockEntry & TT_TYPE_MASK;
if (EntryType == TT_TYPE_TABLE_ENTRY) {
NextTranslationTable = (UINT64*)(*BlockEntry &
TT_ADDRESS_MASK_DESCRIPTION_TABLE);
// The entry is a page table, so we go to the next level
Status = GetMemoryRegionRec (
NextTranslationTable, // Address of the next level page table
TableLevel + 1, // Next Page Table level
(UINTN*)TT_LAST_BLOCK_ADDRESS(NextTranslationTable, TT_ENTRY_COUNT),
BaseAddress, RegionLength, RegionAttributes);
// In case of 'Success', it means the end of the block region has been
found into the upper
// level translation table
if (!EFI_ERROR(Status)) {
return EFI_SUCCESS;
}
} else if (EntryType == BlockEntryType) {
// We have found the BlockEntry attached to the address. We save its start
address (the start
// address might be before the 'BaseAdress') and attributes
*BaseAddress = *BaseAddress & ~(TT_ADDRESS_AT_LEVEL(TableLevel) - 1);
*RegionLength = 0;
*RegionAttributes = *BlockEntry & TT_ATTRIBUTES_MASK;
} else {
// We have an 'Invalid' entry
return EFI_UNSUPPORTED;
}
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