5) For CR4, please use meaning definition for BIT4/BIT5.
if ((Cr4 & BIT4) != 0 && (*PageDirEntry & BIT7) != 0) {
if (((Cr4 & BIT5) != 0 && (UINT64)LinearAddress > 0xFFFFFFFFFULL) ||
6) For IA32 PAE/PSE calculation, same comment for 3 and 4.
7) Last but not least important, would you please share the information on how
do you validate the 32bit PAE/PSE/normal 4K page table?
Thank you
Yao Jiewen
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of Yao,
> Jiewen
> Sent: Thursday, January 4, 2018 9:36 AM
> To: Paulo Alcantara <pa...@paulo.ac>; edk2-devel@lists.01.org
> Cc: Laszlo Ersek <ler...@redhat.com>; Dong, Eric <eric.d...@intel.com>
> Subject: Re: [edk2] [RFC v4 4/6] UefiCpuPkg/CpuExceptionHandlerLib: Add
> helper to valid memory addresses
>
> Some suggestion:
>
> 1) I am not sure if it is proper to use ASSERT in an exception handler,
> because we
> know something is wrong.
>
> ASSERT ((PhysicalAddress & (sizeof (*Pml4TableEntry) - 1)) == 0);
>
> I suggest we just do the check, and return FALSE, if the prerequisite is not
> satisfied.
>
> 2) Can we use meaningful definition for BIT0, BIT7?
>
> if ((*Pml4TableEntry & BIT0) == 0) {
> if ((*PageDirPtrTableEntry & BIT7) != 0) {
>
> 3) I am not sure if I understand below code.
>
> PhysicalAddress = (UINT64)Cr3 & (((1ULL << MaxPhyAddrBits) - 1) << 12);
> PhysicalAddress = *Pml4TableEntry & (((1ULL << MaxPhyAddrBits) - 1) << 12);
> PhysicalAddress = *PageDirPtrTableEntry & (((1ULL << MaxPhyAddrBits) - 1)
> << 12);
> PhysicalAddress = *PageDirEntry & (((1ULL << MaxPhyAddrBits) - 1) << 12);
>
> If MaxPhyAddrBits is 48, you will get "Cr3 & 0x0FFFFFFFFFFFF000". Is that what
> you want? I think we need "Cr3 & 0x0000FFFFFFFFF000"
> Should it be: PhysicalAddress = (UINT64)Cr3 & ((1ULL << MaxPhyAddrBits) - 1) &
> (~0xFFF);
>
> 4) Can we use a more readable way to below? Personally, I do not suggest "<<
> 3",
> which is just the index calculation.
>
> PhysicalAddress = (UINT64)Cr3 & (((1ULL << MaxPhyAddrBits) - 1) << 12);
> PhysicalAddress |= (((UINT64)LinearAddress >> 39) & 0x1FF) << 3;
> Pml4TableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> PhysicalAddress = *Pml4TableEntry & (((1ULL << MaxPhyAddrBits) - 1) << 12);
>
> For example:
> PhysicalAddress = (UINT64)Cr3 & ((1ULL << MaxPhyAddrBits) - 1) & (~0xFFF);
> Pml4TableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> Index= (UINTN)(((UINT64)LinearAddress >> 39) & 0x1FF);
> PhysicalAddress = Pml4TableEntry[Index] & ((1ULL << MaxPhyAddrBits) - 1) &
> (~0xFFF);
>
>
>
> Thank you
> Yao Jiewen
>
>
> > -----Original Message-----
> > From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of
> Paulo
> > Alcantara
> > Sent: Friday, December 29, 2017 12:40 PM
> > To: edk2-devel@lists.01.org
> > Cc: Laszlo Ersek <ler...@redhat.com>; Dong, Eric <eric.d...@intel.com>
> > Subject: [edk2] [RFC v4 4/6] UefiCpuPkg/CpuExceptionHandlerLib: Add helper
> to
> > valid memory addresses
> >
> > Introduce IsLinearAddressValid() function that will be used for
> > validating memory addresses that would get dereferenced during stack
> > traces in IA32 and X64 CPU exceptions.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Cc: Eric Dong <eric.d...@intel.com>
> > Cc: Laszlo Ersek <ler...@redhat.com>
> > Requested-by: Brian Johnson <brian.john...@hpe.com>
> > Requested-by: Jiewen Yao <jiewen....@intel.com>
> > Signed-off-by: Paulo Alcantara <pa...@paulo.ac>
> > ---
> > UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c | 382
> > ++++++++++++++++++++
> > UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h |
> 16 +
> > 2 files changed, 398 insertions(+)
> >
> > diff --git
> > a/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
> > b/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
> > index 867c5c01d6..52b3eb1463 100644
> > --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
> > +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
> > @@ -14,6 +14,9 @@
> >
> > #include "CpuExceptionCommon.h"
> >
> > +#include <Register/Msr.h>
> > +#include <Library/DebugLib.h>
> > +
> > //
> > // Error code flag indicating whether or not an error code will be
> > // pushed on the stack if an exception occurs.
> > @@ -194,3 +197,382 @@ GetPdbFileName (
> > }
> > }
> > }
> > +
> > +/**
> > + Check if a linear address is valid by walking the page tables in 4-level
> > + paging mode.
> > +
> > + @param[in] Cr3 CR3 control register.
> > + @param[in] MaxPhyAddrBits MAXPHYADDRBITS bits.
> > + @param[in] LinearAddress Linear address to be checked.
> > +**/
> > +STATIC
> > +BOOLEAN
> > +Do4LevelPagingModeCheck (
> > + IN UINTN Cr3,
> > + IN UINT8 MaxPhyAddrBits,
> > + IN UINTN LinearAddress
> > + )
> > +{
> > + UINT64 PhysicalAddress;
> > + UINT64 *Pml4TableEntry;
> > + UINT64 *PageDirPtrTableEntry;
> > + UINT64 *PageDirEntry;
> > + UINT64 *PageTableEntry;
> > +
> > + //
> > + // In 4-level paging mode, linear addresses are 48 bits wide
> > + //
> > + if ((UINT64)LinearAddress > (1ULL << 48) - 1) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PML4E
> > + //
> > + PhysicalAddress = (UINT64)Cr3 & (((1ULL << MaxPhyAddrBits) - 1) << 12);
> > + PhysicalAddress |= (((UINT64)LinearAddress >> 39) & 0x1FF) << 3;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*Pml4TableEntry) - 1)) == 0);
> > +
> > + Pml4TableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check if a PDPTE is present
> > + //
> > + if ((*Pml4TableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PDPTE
> > + //
> > + PhysicalAddress = *Pml4TableEntry & (((1ULL << MaxPhyAddrBits) - 1) <<
> > 12);
> > + PhysicalAddress |= (((UINT64)LinearAddress >> 30) & 0x1FF) << 3;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*PageDirPtrTableEntry) - 1)) == 0);
> > +
> > + PageDirPtrTableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check whether a PDPTE or 1GiB page entry is present
> > + //
> > + if ((*PageDirPtrTableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Check if PDPTE maps an 1GiB page
> > + //
> > + if ((*PageDirPtrTableEntry & BIT7) != 0) {
> > + return TRUE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PDE
> > + //
> > + PhysicalAddress = *PageDirPtrTableEntry & (((1ULL << MaxPhyAddrBits) -
> 1)
> > <<
> > + 12);
> > + PhysicalAddress |= (((UINT64)LinearAddress >> 21) & 0x1FF) << 3;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*PageDirEntry) - 1)) == 0);
> > +
> > + PageDirEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check whether a PDE or a 2MiB page entry is present
> > + //
> > + if ((*PageDirEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Check if PDE maps a 2MiB page
> > + //
> > + if ((*PageDirEntry & BIT7) != 0) {
> > + return TRUE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PTE
> > + //
> > + PhysicalAddress = *PageDirEntry & (((1ULL << MaxPhyAddrBits) - 1) <<
> 12);
> > + PhysicalAddress |= (((UINT64)LinearAddress >> 12) & 0x1FF) << 3;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*PageTableEntry) - 1)) == 0);
> > +
> > + PageTableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check if PTE maps a 4KiB page
> > + //
> > + if ((*PageTableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + return TRUE;
> > +}
> > +
> > +/**
> > + Check if a linear address is valid by walking the page tables in 32-bit
> > paging
> > + mode.
> > +
> > + @param[in] Cr3 CR3 control register.
> > + @param[in] Cr4 CR4 control register.
> > + @param[in] LinearAddress Linear address to be checked.
> > +**/
> > +STATIC
> > +BOOLEAN
> > +Do32BitPagingModeCheck (
> > + IN UINTN Cr3,
> > + IN UINTN Cr4,
> > + IN UINTN LinearAddress
> > + )
> > +{
> > + UINT64 PhysicalAddress;
> > + UINT32 *PageDirEntry;
> > + UINT32 *PageTableEntry;
> > +
> > + if (LinearAddress > MAX_UINT32) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PDE
> > + //
> > + PhysicalAddress = (UINT32)Cr3 & (((1ULL << 20) - 1) << 12);
> > + PhysicalAddress |= (((UINT32)LinearAddress >> 22) & 0x3FF) << 2;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*PageDirEntry) - 1)) == 0);
> > +
> > + PageDirEntry = (UINT32 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check whether a PTE or a 4MiB page is present
> > + //
> > + if ((*PageDirEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Check if PDE maps a 4MiB page
> > + //
> > + if ((Cr4 & BIT4) != 0 && (*PageDirEntry & BIT7) != 0) {
> > + return TRUE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PTE
> > + //
> > + PhysicalAddress = *PageDirEntry & (((1ULL << 20) - 1) << 12);
> > + PhysicalAddress |= (((UINT32)LinearAddress >> 12) & 0x3FF) << 2;
> > +
> > + ASSERT ((PhysicalAddress & (sizeof (*PageTableEntry) - 1)) == 0);
> > +
> > + PageTableEntry = (UINT32 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check if PTE maps a 4KiB page
> > + //
> > + if ((*PageTableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + return TRUE;
> > +}
> > +
> > +/**
> > + Check if a linear address is valid by walking the page tables in PAE
> > paging
> > + mode.
> > +
> > + @param[in] Cr3 CR3 control register.
> > + @param[in] MaxPhyAddrBits MAXPHYADDRBITS bits.
> > + @param[in] LinearAddress Linear address to be checked.
> > +**/
> > +STATIC
> > +BOOLEAN
> > +DoPAEPagingModeCheck (
> > + IN UINTN Cr3,
> > + IN UINT8 MaxPhyAddrBits,
> > + IN UINTN LinearAddress
> > + )
> > +{
> > + UINT64 PhysicalAddress;
> > + UINT64 *PageDirPtrTableEntry;
> > + UINT64 *PageDirEntry;
> > + UINT64 *PageTableEntry;
> > +
> > + if (LinearAddress > MAX_UINT32) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PDPTE
> > + //
> > + PhysicalAddress = (UINT32)Cr3 >> 5;
> > +
> > + //
> > + // Select PDPTE register
> > + //
> > + PhysicalAddress +=
> > + ((UINT32)LinearAddress >> 30) * sizeof (*PageDirPtrTableEntry);
> > +
> > + PageDirPtrTableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check if PDE is present
> > + //
> > + if ((*PageDirPtrTableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + PhysicalAddress = *PageDirPtrTableEntry & (((1ULL << MaxPhyAddrBits) -
> 1)
> > <<
> > + 12);
> > + PhysicalAddress |= ((LinearAddress >> 21) & 0x1FF) << 3;
> > + ASSERT ((PhysicalAddress & (sizeof (*PageDirEntry) - 1)) == 0);
> > +
> > + PageDirEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check whether a PTE or a 2MiB page is present
> > + //
> > + if ((*PageDirEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Check if PDE maps a 2MiB page
> > + //
> > + if ((*PageDirEntry & BIT7) != 0) {
> > + return TRUE;
> > + }
> > +
> > + //
> > + // Calculate physical address of PTE
> > + //
> > + PhysicalAddress = *PageDirEntry & (((1ULL << MaxPhyAddrBits) - 1) <<
> 12);
> > + PhysicalAddress |= ((LinearAddress >> 12) & 0x1FF) << 3;
> > + ASSERT ((PhysicalAddress & (sizeof (*PageTableEntry) - 1)) == 0);
> > +
> > + PageTableEntry = (UINT64 *)(UINTN)PhysicalAddress;
> > +
> > + //
> > + // Check if PTE maps a 4KiB page
> > + //
> > + if ((*PageTableEntry & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + return TRUE;
> > +}
> > +
> > +/**
> > + Check if a linear address is valid.
> > +
> > + @param[in] Cr0 CR0 control register.
> > + @param[in] Cr3 CR3 control register.
> > + @param[in] Cr4 CR4 control register.
> > + @param[in] LinearAddress Linear address to be checked.
> > +**/
> > +BOOLEAN
> > +IsLinearAddressValid (
> > + IN UINTN Cr0,
> > + IN UINTN Cr3,
> > + IN UINTN Cr4,
> > + IN UINTN LinearAddress
> > + )
> > +{
> > + UINT32 Eax;
> > + UINT32 Edx;
> > + UINT8 MaxPhyAddrBits;
> > + MSR_IA32_EFER_REGISTER Msr;
> > + BOOLEAN AddressValid;
> > +
> > + //
> > + // Check for valid input parameters
> > + //
> > + if (Cr0 == 0 || Cr4 == 0 || LinearAddress == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Check if paging is disabled
> > + //
> > + if ((Cr0 & BIT31) == 0) {
> > + //
> > + // If CR4.PAE bit is set, then the linear (or physical) address
> > supports
> > + // only up to 36 bits.
> > + //
> > + if (((Cr4 & BIT5) != 0 && (UINT64)LinearAddress > 0xFFFFFFFFFULL) ||
> > + LinearAddress > 0xFFFFFFFF) {
> > + return FALSE;
> > + }
> > +
> > + return TRUE;
> > + }
> > +
> > + //
> > + // Paging can be enabled only if CR0.PE bit is set
> > + //
> > + if ((Cr0 & BIT0) == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // CR3 register cannot be zero if paging is enabled
> > + //
> > + if (Cr3 == 0) {
> > + return FALSE;
> > + }
> > +
> > + //
> > + // Get MAXPHYADDR bits
> > + //
> > + AsmCpuid (0x80000000, &Eax, NULL, NULL, NULL);
> > + if (Eax >= 0x80000008) {
> > + AsmCpuid (0x80000008, &Eax, NULL, NULL, NULL);
> > + MaxPhyAddrBits = (UINT8)Eax;
> > + } else {
> > + AsmCpuid (1, NULL, NULL, NULL, &Edx);
> > + if ((Edx & BIT6) != 0) {
> > + MaxPhyAddrBits = 36;
> > + } else {
> > + MaxPhyAddrBits = 32;
> > + }
> > + }
> > +
> > + ASSERT (MaxPhyAddrBits > 0);
> > +
> > + AddressValid = FALSE;
> > +
> > + //
> > + // check if CR4.PAE bit is not set
> > + //
> > + if ((Cr4 & BIT5) == 0) {
> > + //
> > + // Check if linear address is valid in 32-bit paging mode
> > + //
> > + AddressValid = Do32BitPagingModeCheck (Cr3, Cr4, LinearAddress);
> > + } else {
> > + if (MaxPhyAddrBits > 52) {
> > + return FALSE;
> > + }
> > +
> > + Msr.Uint64 = AsmReadMsr64 (MSR_IA32_EFER);
> > +
> > + if (Msr.Bits.LME == 0) {
> > + //
> > + // Check if linear address is valid in PAE paging mode
> > + //
> > + AddressValid = DoPAEPagingModeCheck (Cr3, MaxPhyAddrBits,
> > LinearAddress);
> > + } else {
> > + //
> > + // Check if linear address is valid in 4-level paging mode
> > + //
> > + AddressValid = Do4LevelPagingModeCheck (Cr3, MaxPhyAddrBits,
> > + LinearAddress);
> > + }
> > + }
> > +
> > + return AddressValid;
> > +}
> > diff --git
> > a/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h
> > b/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h
> > index ec46c2d9d3..1b51034c25 100644
> > --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h
> > +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.h
> > @@ -330,5 +330,21 @@ GetPdbFileName (
> > OUT CHAR8 **PdbFileName
> > );
> >
> > +/**
> > + Check if a linear address is valid.
> > +
> > + @param[in] Cr0 CR0 control register.
> > + @param[in] Cr3 CR3 control register.
> > + @param[in] Cr4 CR4 control register.
> > + @param[in] LinearAddress Linear address to be checked.
> > +**/
> > +BOOLEAN
> > +IsLinearAddressValid (
> > + IN UINTN Cr0,
> > + IN UINTN Cr3,
> > + IN UINTN Cr4,
> > + IN UINTN LinearAddress
> > + );
> > +
> > #endif
> >
> > --
> > 2.14.3
> >
> > _______________________________________________
> > edk2-devel mailing list
> > edk2-devel@lists.01.org
> > https://lists.01.org/mailman/listinfo/edk2-devel
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel
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