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ArmPkg/CpuDxe ARM: Fix page-to-section attribute conversion 

The section-to-page attribute conversion takes the shareability and
execute-never attributes into account, whereas the page-to-section
counterpart does not. The result is that GetMemoryRegionPage () -which
takes a section attribute argument (via *RegionAttributes) that is
ostensibly based on the first page in the range, but differs from the
actual page attributes when converted back- may return with a
RegionLength of zero. This is incorrect, and confuses code that scans a
region by calling GetMemoryRegion () in sequence.

So fix the conversion, and ASSERT () on a non-zero region length.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
This commit is contained in:
Ard Biesheuvel 2023-02-06 19:29:09 +01:00 committed by mergify[bot]
parent 3b76284883
commit 699372d388
2 changed files with 5 additions and 0 deletions
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3
ArmPkg/Drivers/CpuDxe/Arm/Mmu.c
View File

@ -480,6 +480,8 @@ GetMemoryRegion (
PageAttributes = PageTable[PageTableIndex] & TT_DESCRIPTOR_PAGE_ATTRIBUTE_MASK;
*RegionAttributes = TT_DESCRIPTOR_CONVERT_TO_SECTION_CACHE_POLICY (PageAttributes) |
TT_DESCRIPTOR_CONVERT_TO_SECTION_S (PageAttributes) |
TT_DESCRIPTOR_CONVERT_TO_SECTION_XN (PageAttributes) |
TT_DESCRIPTOR_CONVERT_TO_SECTION_AP (PageAttributes);
}
@ -494,6 +496,7 @@ GetMemoryRegion (
// Scan the page table to find the end of the region.
Status = GetMemoryRegionPage (PageTable, BaseAddress, RegionLength, RegionAttributes);
ASSERT (*RegionLength > 0);
// If we have found the end of the region (Status == EFI_SUCCESS) then we exit the for-loop
if (Status == EFI_SUCCESS) {

2
ArmPkg/Include/Chipset/ArmV7Mmu.h
View File

@ -128,6 +128,8 @@
#define TT_DESCRIPTOR_CONVERT_TO_PAGE_CACHE_POLICY(Desc) ((((Desc) & (0x3 << 12)) >> 6) | (Desc & (0x3 << 2)))
#define TT_DESCRIPTOR_CONVERT_TO_SECTION_AP(Desc) ((((Desc) & TT_DESCRIPTOR_PAGE_AP_MASK) << 6) & TT_DESCRIPTOR_SECTION_AP_MASK)
#define TT_DESCRIPTOR_CONVERT_TO_SECTION_S(Desc) ((((Desc) & TT_DESCRIPTOR_PAGE_S_MASK) << 6) & TT_DESCRIPTOR_SECTION_S_MASK)
#define TT_DESCRIPTOR_CONVERT_TO_SECTION_XN(Desc) ((((Desc) & TT_DESCRIPTOR_PAGE_XN_MASK) << 4) & TT_DESCRIPTOR_SECTION_XN_MASK)
#define TT_DESCRIPTOR_CONVERT_TO_SECTION_CACHE_POLICY(Desc) ((((Desc) & (0x3 << 6)) << 6) | (Desc & (0x3 << 2)))
#define TT_DESCRIPTOR_SECTION_ATTRIBUTE_MASK (TT_DESCRIPTOR_SECTION_NS_MASK | TT_DESCRIPTOR_SECTION_NG_MASK | \