Re: [edk2-devel] [PATCH v1 2/2] StandaloneMmPkg: Fix HOB space and heap space conflicted issue

["Ming Huang" <huangming@linux.alibaba.com>]

在 5/3/22 5:10 PM, Ard Biesheuvel 写道:
> On Wed, 9 Feb 2022 at 13:26, Ming Huang <huangming@linux.alibaba.com> wrote:
>>
>> The heap space will be rewrote if a StandloneMmPkg module create HOB
>> by BuildGuidHob() interface and write data to HOB space.
> 
> Can you elaborate? What is supposed to happen and why, and what is
> happening instead?

I tried my best to explain the issue:

-----------------------------<--HandOffHob->EfiFreeMemoryTop
|                           |
|                           |
|                           |
|                           |
|                           |
|                           |
|          mMmMemoryMap     |
|---------------------------|<--HandOffHob->EfiFreeMemoryBottom
|          HobEnd           |
|---------------------------|<--HandOffHob->EfiEndOfHobList
|                           |
|          Hob #1           |
-----------------------------<--MmHobStart
1 The mMmMemoryMap which use for free page is on above the HobEnd.
2 Create a hob by BuildGuidHob(), the HobEnd will move up and cover
  the structure or list using by free page.

After this patch, there is a pre-allocation space for creating hob.

-----------------------------<--HandOffHob->EfiFreeMemoryTop
|                           |
|                           |
|                           |
|                           |
|         mMmMemoryMap      |
|---------------------------|<--HandOffHob->EfiFreeMemoryBottom
|          Hob free space   | by PcdMemoryHobSize
|---------------------------|
|          HobEnd           |
|---------------------------|<--HandOffHob->EfiEndOfHobList
|                           |
|          Hob #1           |
-----------------------------<--MmHobStart

> 
>> Add a PCD PcdMemoryHobSize for pre-allocation a space to create HOB to
>> fix this issue.
>>
>> Signed-off-by: Ming Huang <huangming@linux.alibaba.com>
>> ---
>>  StandaloneMmPkg/Core/StandaloneMmCore.c   | 17 ++++++++++++++++-
>>  StandaloneMmPkg/Core/StandaloneMmCore.inf |  3 +++
>>  StandaloneMmPkg/StandaloneMmPkg.dec       |  2 ++
>>  3 files changed, 21 insertions(+), 1 deletion(-)
>>
>> diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.c b/StandaloneMmPkg/Core/StandaloneMmCore.c
>> index d221f1d111..1cf259d946 100644
>> --- a/StandaloneMmPkg/Core/StandaloneMmCore.c
>> +++ b/StandaloneMmPkg/Core/StandaloneMmCore.c
>> @@ -512,6 +512,9 @@ StandaloneMmMain (
>>    EFI_MMRAM_DESCRIPTOR            *MmramRanges;
>>    UINTN                           MmramRangeCount;
>>    EFI_HOB_FIRMWARE_VOLUME         *BfvHob;
>> +  EFI_HOB_HANDOFF_INFO_TABLE      *HandOffHobNew;
>> +  EFI_HOB_HANDOFF_INFO_TABLE      *HandOffHobOrg;
>> +  UINT64                          MaxHobSize = PcdGet64 (PcdMemoryHobSize);
>>
>>    ProcessLibraryConstructorList (HobStart, &gMmCoreMmst);
>>
>> @@ -619,10 +622,22 @@ StandaloneMmMain (
>>    //
>>    HobSize = GetHobListSize (HobStart);
>>    DEBUG ((DEBUG_INFO, "HobSize - 0x%x\n", HobSize));
>> -  MmHobStart = AllocatePool (HobSize);
>> +  ASSERT (HobSize <= MaxHobSize);
>> +  MmHobStart = AllocatePool (MaxHobSize);
>>    DEBUG ((DEBUG_INFO, "MmHobStart - 0x%x\n", MmHobStart));
>>    ASSERT (MmHobStart != NULL);
>>    CopyMem (MmHobStart, HobStart, HobSize);
>> +  //
>> +  // Initlialize the new HOB table
>> +  //
>> +  HandOffHobOrg = (EFI_HOB_HANDOFF_INFO_TABLE *)HobStart;
>> +  HandOffHobNew = (EFI_HOB_HANDOFF_INFO_TABLE *)MmHobStart;
>> +  HandOffHobNew->EfiEndOfHobList = (EFI_PHYSICAL_ADDRESS)MmHobStart +
>> +    (HandOffHobOrg->EfiEndOfHobList - (EFI_PHYSICAL_ADDRESS)HobStart);
>> +  HandOffHobNew->EfiFreeMemoryBottom = HandOffHobNew->EfiEndOfHobList +
>> +                                       sizeof (EFI_HOB_GENERIC_HEADER);
>> +  HandOffHobNew->EfiFreeMemoryTop = (EFI_PHYSICAL_ADDRESS)MmHobStart + MaxHobSize;
>> +
>>    Status = MmInstallConfigurationTable (&gMmCoreMmst, &gEfiHobListGuid, MmHobStart, HobSize);
>>    ASSERT_EFI_ERROR (Status);
>>
>> diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.inf b/StandaloneMmPkg/Core/StandaloneMmCore.inf
>> index c44b9ff333..37e6135d73 100644
>> --- a/StandaloneMmPkg/Core/StandaloneMmCore.inf
>> +++ b/StandaloneMmPkg/Core/StandaloneMmCore.inf
>> @@ -76,6 +76,9 @@
>>    gEfiEventExitBootServicesGuid
>>    gEfiEventReadyToBootGuid
>>
>> +[FixedPcd]
>> +  gStandaloneMmPkgTokenSpaceGuid.PcdMemoryHobSize
>> +
>>  #
>>  # This configuration fails for CLANGPDB, which does not support PIE in the GCC
>>  # sense. Such however is required for ARM family StandaloneMmCore
>> diff --git a/StandaloneMmPkg/StandaloneMmPkg.dec b/StandaloneMmPkg/StandaloneMmPkg.dec
>> index 46784d94e4..cf554676e2 100644
>> --- a/StandaloneMmPkg/StandaloneMmPkg.dec
>> +++ b/StandaloneMmPkg/StandaloneMmPkg.dec
>> @@ -48,3 +48,5 @@
>>    gEfiStandaloneMmNonSecureBufferGuid      = { 0xf00497e3, 0xbfa2, 0x41a1, { 0x9d, 0x29, 0x54, 0xc2, 0xe9, 0x37, 0x21, 0xc5 }}
>>    gEfiArmTfCpuDriverEpDescriptorGuid       = { 0x6ecbd5a1, 0xc0f8, 0x4702, { 0x83, 0x01, 0x4f, 0xc2, 0xc5, 0x47, 0x0a, 0x51 }}
>>
>> +[PcdsFixedAtBuild]
>> +  gStandaloneMmPkgTokenSpaceGuid.PcdMemoryHobSize|0x00000000|UINT64|0x00000004
>> --
>> 2.17.1
>>
> 
> 
> 
>