Ard Biesheuvel ce82984fe7 ArmPkg/CpuDxe: translate invalid memory types in EfiAttributeToArmAttribute ... The single user of EfiAttributeToArmAttribute () is the protocol method EFI_CPU_ARCH_PROTOCOL.SetMemoryAttributes(), which uses the return value to compare against the ARM attributes of an existing mapping, to infer whether it is actually necessary to change anything, or whether the requested update is redundant. This saves some cache and TLB maintenance on 32-bit ARM systems that use uncached translation tables. However, EFI_CPU_ARCH_PROTOCOL.SetMemoryAttributes() may be invoked with only permission bits set, in which case the implied requested action is to update the permissions of the region without modifying the cacheability attributes. This is currently not possible, because EfiAttributeToArmAttribute () ASSERT()s [on AArch64] on Attributes arguments that lack a cacheability bit. So let's simply return TT_ATTR_INDX_MASK (AArch64) or TT_DESCRIPTOR_SECTION_TYPE_FAULT (ARM) in these cases (or'ed with the appropriate permission bits). This way, the return value is equally suitable for checking whether the attributes need to be modified, but in a way that accommodates the use without a cacheability bit set. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>		2017-02-21 17:23:03 +00:00
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Mmu.c	ArmPkg/CpuDxe: translate invalid memory types in EfiAttributeToArmAttribute	2017-02-21 17:23:03 +00:00