From 3b76284883df833170f741c9fb4037579635b7f2 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 9 Feb 2023 10:01:45 +0100 Subject: ArmPkg/ArmMmuLib ARM: Split off XN page descriptor bit from type field With large page support out of the picture, we can treat bits 1 and 0 of the page descriptor as individual valid and XN bits, instead of treating XN as a page type. Doing so aligns the handling of the attribute with the section descriptor layout, as well as the XN handling on AArch64, and this is beneficial for maintainability. Signed-off-by: Ard Biesheuvel Reviewed-by: Leif Lindholm --- ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'ArmPkg/Library/ArmMmuLib/Arm') diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c index 9ca00c976d..12d0f4c30f 100644 --- a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c +++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c @@ -104,12 +104,8 @@ 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; - if ((Attributes & EFI_MEMORY_XP) != 0) { - EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE_XN; - } else { - EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE; - } + EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK | TT_DESCRIPTOR_PAGE_XN_MASK; + EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE; // Although the PI spec is unclear on this, the GCD guarantees that only // one Attribute bit is set at a time, so the order of the conditionals below @@ -148,6 +144,10 @@ UpdatePageEntries ( EntryValue |= TT_DESCRIPTOR_PAGE_AP_RW_RW; } + if ((Attributes & EFI_MEMORY_XP) != 0) { + EntryValue |= TT_DESCRIPTOR_PAGE_XN_MASK; + } + // Obtain page table base FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress (); -- cgit v1.2.3