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UefiCpuPkg/MtrrLib: Fix bug that may incorrectly set <1MB attribute

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MtrrLibSetBelow1MBMemoryAttribute() may be called multiple times.
It's possible that in a 2nd call, Modified[0] is set to TRUE in
1st call but ClearMasks[0] and OrMasks[0] is uninitialized in
2nd call. It causes FixedSettings->Mtrr[0] be set to random
data.

The patch fixes this issue by introducing a local Modified[]
array and only updates FixedSettings->Mtrr[] when LocalModified[i]
is TRUE.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
This commit is contained in:
Ruiyu Ni 2017-10-19 10:43:08 +08:00
parent 1e3f7a3782
commit 86cabbcfa0
1 changed files with 15 additions and 4 deletions
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19
UefiCpuPkg/Library/MtrrLib/MtrrLib.c
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@ -2114,22 +2114,32 @@ MtrrLibSetBelow1MBMemoryAttribute (
UINT64 OrMask;
UINT64 ClearMasks[ARRAY_SIZE (mMtrrLibFixedMtrrTable)];
UINT64 OrMasks[ARRAY_SIZE (mMtrrLibFixedMtrrTable)];
BOOLEAN LocalModified[ARRAY_SIZE (mMtrrLibFixedMtrrTable)];
ASSERT (BaseAddress < BASE_1MB);
SetMem (LocalModified, sizeof (LocalModified), FALSE);
//
// (Value & ~0 | 0) still equals to (Value)
//
SetMem64 (ClearMasks, sizeof (ClearMasks), 0);
SetMem64 (OrMasks, sizeof (OrMasks), 0);
MsrIndex = (UINT32)-1;
while ((BaseAddress < BASE_1MB) && (Length != 0)) {
Status = MtrrLibProgramFixedMtrr (Type, &BaseAddress, &Length, &MsrIndex, &ClearMask, &OrMask);
if (RETURN_ERROR (Status)) {
return Status;
}
ClearMasks[MsrIndex] = ClearMask;
OrMasks[MsrIndex] = OrMask;
Modified[MsrIndex] = TRUE;
ClearMasks[MsrIndex] = ClearMask;
OrMasks[MsrIndex] = OrMask;
Modified[MsrIndex] = TRUE;
LocalModified[MsrIndex] = TRUE;
}
for (MsrIndex = 0; MsrIndex < ARRAY_SIZE (mMtrrLibFixedMtrrTable); MsrIndex++) {
if (Modified[MsrIndex]) {
if (LocalModified[MsrIndex]) {
FixedSettings->Mtrr[MsrIndex] = (FixedSettings->Mtrr[MsrIndex] & ~ClearMasks[MsrIndex]) | OrMasks[MsrIndex];
}
}
@ -2354,6 +2364,7 @@ MtrrSetMemoryAttributesInMtrrSettings (
//
// 3. Apply the below-1MB memory attribute settings.
//
ZeroMem (WorkingFixedSettings.Mtrr, sizeof (WorkingFixedSettings.Mtrr));
for (Index = 0; Index < RangeCount; Index++) {
if (Ranges[Index].BaseAddress >= BASE_1MB) {
continue;