Currently, we allocate a full page for the root translation table, even if the configured translation only requires two entries (16 bytes) for the root level, which happens to be the case for a 40 bit VA. Likewise, for a 36-bit VA space, the root table only needs 16 entries of 8 bytes each, adding up to 128 bytes.
So switch to a pool allocation for the root table, but take into account that the architecture requires it to be naturally aligned to its size, i.e., a 64 byte table requires 64 byte alignment, whereas pool allocations in general are only guaranteed to be aligned to 8 bytes. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <[email protected]> --- ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 23 +++++++++++++------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c index b5900a761f80..297771a42761 100644 --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c @@ -580,11 +580,12 @@ ArmConfigureMmu ( ) { VOID* TranslationTable; - UINTN TranslationTablePageCount; + VOID* TranslationTableBuffer; UINT32 TranslationTableAttribute; UINT64 MaxAddress; UINTN T0SZ; UINTN RootTableEntryCount; + UINTN RootTableEntrySize; UINT64 TCR; RETURN_STATUS Status; @@ -656,12 +657,18 @@ ArmConfigureMmu ( // Set TCR ArmSetTCR (TCR); - // Allocate pages for translation table - TranslationTablePageCount = EFI_SIZE_TO_PAGES(RootTableEntryCount * sizeof(UINT64)); - TranslationTable = (UINT64*)AllocateAlignedPages (TranslationTablePageCount, TT_ALIGNMENT_DESCRIPTION_TABLE); - if (TranslationTable == NULL) { + // Allocate pages for translation table. Pool allocations are 8 byte aligned, + // but we may require a higher alignment based on the size of the root table. + RootTableEntrySize = RootTableEntryCount * sizeof(UINT64); + TranslationTableBuffer = AllocatePool (2 * RootTableEntrySize - 8); + if (TranslationTableBuffer == NULL) { return RETURN_OUT_OF_RESOURCES; } + // + // Naturally align the root table + // + TranslationTable = (VOID *)((UINTN)(TranslationTableBuffer - 1) | (RootTableEntrySize - 1)) + 1; + // We set TTBR0 just after allocating the table to retrieve its location from the subsequent // functions without needing to pass this value across the functions. The MMU is only enabled // after the translation tables are populated. @@ -672,10 +679,10 @@ ArmConfigureMmu ( } if (TranslationTableSize != NULL) { - *TranslationTableSize = RootTableEntryCount * sizeof(UINT64); + *TranslationTableSize = RootTableEntrySize; } - ZeroMem (TranslationTable, RootTableEntryCount * sizeof(UINT64)); + ZeroMem (TranslationTable, RootTableEntrySize); // Disable MMU and caches. ArmDisableMmu() also invalidates the TLBs ArmDisableMmu (); @@ -735,7 +742,7 @@ ArmConfigureMmu ( return RETURN_SUCCESS; FREE_TRANSLATION_TABLE: - FreePages (TranslationTable, TranslationTablePageCount); + FreePool (TranslationTableBuffer); return Status; } -- 2.7.4 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
