Re: [MdeModulePkg][PeiCore] I seemed to have crashed the PEI Core by grabbing memory from PeiTemporaryRamBase?

[Andrew Fish <afish@apple.com>]

> On Aug 15, 2016, at 8:54 AM, Gao, Liming <liming.gao@intel.com> wrote:
> 
> Andrew:
>  In permanent memory, PeiCore places heap base as stack top. Heap is above stack. There is no hole between them. SEC needs to follow this layout and migrate the temporary memory to permanent memory. It should copy TemporaryRam HEAP and STACK range separately. HEAP range is specified by PeiTemporaryRamBase and PeiTemporaryRamSize, and STACK range is specified by StackBase and StackSize. The grabbed memory is not migrated, because PeiCore doesn't know it. But, EmulatorPkg Sec SecTemporaryRamSupport() migrates the whole temporary memory together. The grabbed memory is also migrated and wrongly regarded as heap data. So, the fix is to update SecTemporaryRamSupport() implementation in SEC. 
> 

Limiing,

I don't see any info in the PPI definition or the PI spec that defines the heap and stack are copied separately? The PPI just passes the entire ranges? That is why I assumes in the PPI case the offsets should be relative to the big shift?

/**
  This service of the EFI_PEI_TEMPORARY_RAM_SUPPORT_PPI that migrates temporary RAM into
  permanent memory.

  @param PeiServices            Pointer to the PEI Services Table.
  @param TemporaryMemoryBase    Source Address in temporary memory from which the SEC or PEIM will copy the
                                Temporary RAM contents.
  @param PermanentMemoryBase    Destination Address in permanent memory into which the SEC or PEIM will copy the
                                Temporary RAM contents.
  @param CopySize               Amount of memory to migrate from temporary to permanent memory.

  @retval EFI_SUCCESS           The data was successfully returned.
  @retval EFI_INVALID_PARAMETER PermanentMemoryBase + CopySize > TemporaryMemoryBase when
                                TemporaryMemoryBase > PermanentMemoryBase.

**/
typedef
EFI_STATUS
(EFIAPI * TEMPORARY_RAM_MIGRATION)(
  IN CONST EFI_PEI_SERVICES   **PeiServices,
  IN EFI_PHYSICAL_ADDRESS     TemporaryMemoryBase,
  IN EFI_PHYSICAL_ADDRESS     PermanentMemoryBase,
  IN UINTN                    CopySize
);


Thanks,

Andrew Fish

> Thanks
> Liming
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Andrew Fish
> Sent: Saturday, August 13, 2016 7:25 AM
> To: edk2-devel <edk2-devel@lists.01.org>
> Subject: [edk2] [MdeModulePkg][PeiCore] I seemed to have crashed the PEI Core by grabbing memory from PeiTemporaryRamBase?
> 
> I grabbed some memory between SEC and the PEI Core by adjusting SecCoreData-> PeiTemporaryRamBase and SecCoreData-> PeiTemporaryRamSize.
> 
> When looking at the code I don't really understand the logic of the algorithm? So maybe I'm doing something wrong. 
> 
> This adjustment does not seem right to me?
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c#L768
>      //
>      // Heap Offset
>      //
>      BaseOfNewHeap = TopOfNewStack;
>      if (BaseOfNewHeap >= (UINTN)SecCoreData->PeiTemporaryRamBase) {
>        Private->HeapOffsetPositive = TRUE;
>        Private->HeapOffset = (UINTN)(BaseOfNewHeap - (UINTN)SecCoreData->PeiTemporaryRamBase);
>      } else {
>        Private->HeapOffsetPositive = FALSE;
>        Private->HeapOffset = (UINTN)((UINTN)SecCoreData->PeiTemporaryRamBase - BaseOfNewHeap);
>      }
> 
> 
> The above code seems to be making a very strange adjustment. I noticed the adjustment in my failing case was off by 0xC0 which is the amount of memory I carved out prior to entering the PEI Core. 
> 
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c#L796
> 
>      //
>      // Temporary Ram Support PPI is provided by platform, it will copy 
>      // temporary memory to permenent memory and do stack switching.
>      // After invoking Temporary Ram Support PPI, the following code's 
>      // stack is in permanent memory.
>      //
>      TemporaryRamSupportPpi->TemporaryRamMigration (
>                                PeiServices,
>                                TemporaryRamBase,
>                                (EFI_PHYSICAL_ADDRESS)(UINTN)(TopOfNewStack - TemporaryStackSize),
>                                TemporaryRamSize
>                                );
> 
> 
> And this is also a case in which the stack got bigger. But it seems to me the shift if really defined by TemporaryRamBase, TopOfNewStack, and TemporaryStackSize in this case. 
> 
> The failure I hit was OldCoreData->Fv pointer was shifted so when the PPI was called the system crashed. Is this a bug in the gEfiTemporaryRamSupportPpiGuid path?
> 
> If I changed the HeadOffset algorithm my crash went away? Private->HeapOffset = ((UINTN)TopOfNewStack - TemporaryStackSize) - TemporaryRamBase;
> 
> Thanks,
> 
> Andrew Fish
> 
> PS My failure case was the EmulatorPkg. I've not had a chance to verify this failure in the open source yet, but I'm guessing reversing this #if will make it happen.
> 
> 
> https://github.com/tianocore/edk2/blob/master/EmulatorPkg/Sec/Sec.c#L107
> 
> #if 0
>  // Tell the PEI Core to not use our buffer in temp RAM
>  SecPpiList = (EFI_PEI_PPI_DESCRIPTOR *)SecCoreData->PeiTemporaryRamBase;
>  SecCoreData->PeiTemporaryRamBase = (VOID *)((UINTN)SecCoreData->PeiTemporaryRamBase + SecReseveredMemorySize);
>  SecCoreData->PeiTemporaryRamSize -= SecReseveredMemorySize;
> #else
>  {
>    //
>    // When I subtrack from SecCoreData->PeiTemporaryRamBase PEI Core crashes? Either there is a bug
>    // or I don't understand temp RAM correctly?
>    //
>    EFI_PEI_PPI_DESCRIPTOR    PpiArray[10];
> 
>    SecPpiList = &PpiArray[0];
>    ASSERT (sizeof (PpiArray) >= SecReseveredMemorySize);
>  }
> #endif
> 
> 
> 
> 
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