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ArmPkg/ArmMmuLib ARM: fix thinko in second level page table handling 

PopulateLevel2PageTable () is invoked for [parts of] mappings that
start or end on a non-1 MB aligned address (or both). The size of
the mapping depends on both the start address modulo 1 MB and the
length of the mapping, but the logic that calculates this size is
flawed: subtracting 'start address modulo 1 MB' could result in a
negative value for the remaining length, which is obviously wrong.

So instead, take either RemainLength, or the rest of the 1 MB
block, whichever is smaller.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Eugene Cohen <eugene@hp.com>
This commit is contained in:
Ard Biesheuvel 2019-01-04 19:04:32 +01:00
parent e3ad54faa8
commit 28ce4cb359
1 changed files with 2 additions and 2 deletions
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4
ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
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@ -294,8 +294,8 @@ FillTranslationTable (
PhysicalBase += TT_DESCRIPTOR_SECTION_SIZE;
RemainLength -= TT_DESCRIPTOR_SECTION_SIZE;
} else {
PageMapLength = MIN (RemainLength, TT_DESCRIPTOR_SECTION_SIZE) -
(PhysicalBase % TT_DESCRIPTOR_SECTION_SIZE);
PageMapLength = MIN (RemainLength, TT_DESCRIPTOR_SECTION_SIZE -
(PhysicalBase % TT_DESCRIPTOR_SECTION_SIZE));
// Case: Physical address aligned on the Section Size (1MB) && the length
// does not fill a section