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IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection

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Legacy has to access interrupt vector, BDA, etc. located in memory between
0-4095. To allow as much code as possible to be monitored by NULL pointer
detection, we add code to temporarily disable this feature right before
those memory access and enable it again afterwards.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
This commit is contained in:
Jian J Wang
2017-10-09 22:01:49 +08:00
committed by Eric Dong
parent f8c1133bbb
commit d057d8c4e9
10 changed files with 338 additions and 10 deletions
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27
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/Thunk.c
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@@ -57,7 +57,11 @@ LegacyBiosInt86 (
IN EFI_IA32_REGISTER_SET *Regs
)
{
UINT32 *VectorBase;
UINT16 Segment;
UINT16 Offset;
LEGACY_BIOS_INSTANCE *Private;
Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
Regs->X.Flags.Reserved1 = 1;
Regs->X.Flags.Reserved2 = 0;
@@ -72,12 +76,15 @@ LegacyBiosInt86 (
// The base address of legacy interrupt vector table is 0.
// We use this base address to get the legacy interrupt handler.
//
VectorBase = 0;
DisableNullDetection ();
Segment = (UINT16)(((UINT32 *)0)[BiosInt] >> 16);
Offset = (UINT16)((UINT32 *)0)[BiosInt];
EnableNullDetection ();
return InternalLegacyBiosFarCall (
This,
(UINT16) ((VectorBase)[BiosInt] >> 16),
(UINT16) (VectorBase)[BiosInt],
Segment,
Offset,
Regs,
&Regs->X.Flags,
sizeof (Regs->X.Flags)
@@ -293,9 +300,15 @@ InternalLegacyBiosFarCall (
UINTN EbdaBaseAddress;
UINTN ReservedEbdaBaseAddress;
EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);
ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
//
// Skip this part of debug code if NULL pointer detection is enabled
//
if ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT0) == 0) {
EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP
- PcdGet32 (PcdEbdaReservedMemorySize);
ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
}
}
);