Re: [PATCH v2] PeiLib : Inform UEFI memory to Linux

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 19 September 2017 at 01:07, Sakar Arora <Sakar.Arora@arm.com> wrote:
> This change will create the possibility for memory space holding the UEFI image to be over-written by the DXE core code, since this space will then be available for allocation.

Yes. But why does this matter after the entire payload has been
decompressed into memory already?


> Any such change, if required, should be done just before booting the OS.
>
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Meenakshi Aggarwal
> Sent: Tuesday, September 19, 2017 6:02 PM
> To: edk2-devel@lists.01.org; leif.lindholm@linaro.org; ard.biesheuvel@linaro.org
> Subject: [edk2] [PATCH v2] PeiLib : Inform UEFI memory to Linux
>
> While creating Hob list, ArmPlatformPkg is hiding UEFI memory.
> whereas this memory can be used by OS.
>
> This patch, allows OS to use UEFI code area.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Udit Kumar <udit.kumar@nxp.com>
> Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@nxp.com>
> ---
>  ArmPlatformPkg/MemoryInitPei/MemoryInitPeiLib.c | 69 -------------------------
>  1 file changed, 69 deletions(-)
>
> diff --git a/ArmPlatformPkg/MemoryInitPei/MemoryInitPeiLib.c b/ArmPlatformPkg/MemoryInitPei/MemoryInitPeiLib.c
> index 2feb11f..d03214b 100644
> --- a/ArmPlatformPkg/MemoryInitPei/MemoryInitPeiLib.c
> +++ b/ArmPlatformPkg/MemoryInitPei/MemoryInitPeiLib.c
> @@ -70,11 +70,7 @@ MemoryPeim (
>  {
>    ARM_MEMORY_REGION_DESCRIPTOR *MemoryTable;
>    EFI_RESOURCE_ATTRIBUTE_TYPE  ResourceAttributes;
> -  UINT64                       ResourceLength;
>    EFI_PEI_HOB_POINTERS         NextHob;
> -  EFI_PHYSICAL_ADDRESS         FdTop;
> -  EFI_PHYSICAL_ADDRESS         SystemMemoryTop;
> -  EFI_PHYSICAL_ADDRESS         ResourceTop;
>    BOOLEAN                      Found;
>
>    // Get Virtual Memory Map from the Platform Library @@ -121,71 +117,6 @@ MemoryPeim (
>      );
>    }
>
> -  //
> -  // Reserved the memory space occupied by the firmware volume
> -  //
> -
> -  SystemMemoryTop = (EFI_PHYSICAL_ADDRESS)PcdGet64 (PcdSystemMemoryBase) + (EFI_PHYSICAL_ADDRESS)PcdGet64 (PcdSystemMemorySize);
> -  FdTop = (EFI_PHYSICAL_ADDRESS)PcdGet64 (PcdFdBaseAddress) + (EFI_PHYSICAL_ADDRESS)PcdGet32 (PcdFdSize);
> -
> -  // EDK2 does not have the concept of boot firmware copied into DRAM. To avoid the DXE
> -  // core to overwrite this area we must mark the region with the attribute non-present
> -  if ((PcdGet64 (PcdFdBaseAddress) >= PcdGet64 (PcdSystemMemoryBase)) && (FdTop <= SystemMemoryTop)) {
> -    Found = FALSE;
> -
> -    // Search for System Memory Hob that contains the firmware
> -    NextHob.Raw = GetHobList ();
> -    while ((NextHob.Raw = GetNextHob (EFI_HOB_TYPE_RESOURCE_DESCRIPTOR, NextHob.Raw)) != NULL) {
> -      if ((NextHob.ResourceDescriptor->ResourceType == EFI_RESOURCE_SYSTEM_MEMORY) &&
> -          (PcdGet64 (PcdFdBaseAddress) >= NextHob.ResourceDescriptor->PhysicalStart) &&
> -          (FdTop <= NextHob.ResourceDescriptor->PhysicalStart + NextHob.ResourceDescriptor->ResourceLength))
> -      {
> -        ResourceAttributes = NextHob.ResourceDescriptor->ResourceAttribute;
> -        ResourceLength = NextHob.ResourceDescriptor->ResourceLength;
> -        ResourceTop = NextHob.ResourceDescriptor->PhysicalStart + ResourceLength;
> -
> -        if (PcdGet64 (PcdFdBaseAddress) == NextHob.ResourceDescriptor->PhysicalStart) {
> -          if (SystemMemoryTop == FdTop) {
> -            NextHob.ResourceDescriptor->ResourceAttribute = ResourceAttributes & ~EFI_RESOURCE_ATTRIBUTE_PRESENT;
> -          } else {
> -            // Create the System Memory HOB for the firmware with the non-present attribute
> -            BuildResourceDescriptorHob (EFI_RESOURCE_SYSTEM_MEMORY,
> -                                        ResourceAttributes & ~EFI_RESOURCE_ATTRIBUTE_PRESENT,
> -                                        PcdGet64 (PcdFdBaseAddress),
> -                                        PcdGet32 (PcdFdSize));
> -
> -            // Top of the FD is system memory available for UEFI
> -            NextHob.ResourceDescriptor->PhysicalStart += PcdGet32(PcdFdSize);
> -            NextHob.ResourceDescriptor->ResourceLength -= PcdGet32(PcdFdSize);
> -          }
> -        } else {
> -          // Create the System Memory HOB for the firmware with the non-present attribute
> -          BuildResourceDescriptorHob (EFI_RESOURCE_SYSTEM_MEMORY,
> -                                      ResourceAttributes & ~EFI_RESOURCE_ATTRIBUTE_PRESENT,
> -                                      PcdGet64 (PcdFdBaseAddress),
> -                                      PcdGet32 (PcdFdSize));
> -
> -          // Update the HOB
> -          NextHob.ResourceDescriptor->ResourceLength = PcdGet64 (PcdFdBaseAddress) - NextHob.ResourceDescriptor->PhysicalStart;
> -
> -          // If there is some memory available on the top of the FD then create a HOB
> -          if (FdTop < NextHob.ResourceDescriptor->PhysicalStart + ResourceLength) {
> -            // Create the System Memory HOB for the remaining region (top of the FD)
> -            BuildResourceDescriptorHob (EFI_RESOURCE_SYSTEM_MEMORY,
> -                                        ResourceAttributes,
> -                                        FdTop,
> -                                        ResourceTop - FdTop);
> -          }
> -        }
> -        Found = TRUE;
> -        break;
> -      }
> -      NextHob.Raw = GET_NEXT_HOB (NextHob);
> -    }
> -
> -    ASSERT(Found);
> -  }
> -
>    // Build Memory Allocation Hob
>    InitMmu (MemoryTable);
>
> --
> 1.9.1
>
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