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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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17
IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
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@@ -2279,6 +2279,7 @@ LegacyBiosInstallRom (
UINTN Function;
EFI_IA32_REGISTER_SET Regs;
UINT8 VideoMode;
UINT8 OldVideoMode;
EFI_TIME BootTime;
UINT32 *BdaPtr;
UINT32 LocalTime;
@@ -2299,6 +2300,7 @@ LegacyBiosInstallRom (
Device = 0;
Function = 0;
VideoMode = 0;
OldVideoMode = 0;
PhysicalAddress = 0;
MaxRomAddr = PcdGet32 (PcdEndOpromShadowAddress);
@@ -2401,6 +2403,8 @@ LegacyBiosInstallRom (
// 2. BBS compliants drives will not change 40:75 until boot time.
// 3. Onboard IDE controllers will change 40:75
//
DisableNullDetection ();
LocalDiskStart = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
if ((Private->Disk4075 + 0x80) < LocalDiskStart) {
//
@@ -2426,6 +2430,9 @@ LegacyBiosInstallRom (
//
VideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
}
EnableNullDetection ();
//
// Notify the platform that we are about to scan the ROM
//
@@ -2466,9 +2473,11 @@ LegacyBiosInstallRom (
// Multiply result by 18.2 for number of ticks since midnight.
// Use 182/10 to avoid floating point math.
//
DisableNullDetection ();
LocalTime = (LocalTime * 182) / 10;
BdaPtr = (UINT32 *) ((UINTN) 0x46C);
*BdaPtr = LocalTime;
EnableNullDetection ();
//
// Pass in handoff data
@@ -2564,7 +2573,11 @@ LegacyBiosInstallRom (
//
// Set mode settings since PrepareToScanRom may change mode
//
if (VideoMode != *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE))) {
DisableNullDetection ();
OldVideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));
EnableNullDetection ();
if (VideoMode != OldVideoMode) {
//
// The active video mode is changed, restore it to original mode.
//
@@ -2604,7 +2617,9 @@ LegacyBiosInstallRom (
}
}
DisableNullDetection ();
LocalDiskEnd = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);
EnableNullDetection ();
//
// Allow platform to perform any required actions after the