Re: [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page setup for APs

["Wang, Jian J" <jian.j.wang@intel.com>]

Hi,

Anyone has any comments on this?

Regards,
Jian


> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Jian J
> Wang
> Sent: Thursday, December 21, 2017 9:27 AM
> To: edk2-devel@lists.01.org
> Cc: Laszlo Ersek <lersek@redhat.com>; Yao, Jiewen <jiewen.yao@intel.com>;
> Dong, Eric <eric.dong@intel.com>
> Subject: [edk2] [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page setup
> for APs
> 
> AP has its own stack for code execution. If PcdCpuStackGuard is enabled,
> the page at the bottom of stack of AP will be disabled (NOT PRESENT) to
> monitor the stack overflow issue. This requires PcdCpuApStackSize to be
> set with value more than one page of memory.
> 
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  1 +
>  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       | 34
> ++++++++++++++++++++++++---
>  2 files changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> index 805641b516..e7b9eb4462 100644
> --- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> @@ -73,4 +73,5 @@
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuMicrocodePatchRegionSize         ##
> CONSUMES
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode                       ## CONSUMES
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate                   ##
> SOMETIMES_CONSUMES
> +  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                  ##
> CONSUMES
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> index 479f8189f6..40c1bf407a 100644
> --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> @@ -17,6 +17,7 @@
>  #include <Library/UefiLib.h>
>  #include <Library/UefiBootServicesTableLib.h>
>  #include <Library/DebugAgentLib.h>
> +#include <Library/DxeServicesTableLib.h>
> 
>  #include <Protocol/Timer.h>
> 
> @@ -288,9 +289,12 @@ InitMpGlobalData (
>    IN CPU_MP_DATA               *CpuMpData
>    )
>  {
> -  EFI_STATUS                 Status;
> -  EFI_PHYSICAL_ADDRESS       Address;
> -  UINTN                      ApSafeBufferSize;
> +  EFI_STATUS                          Status;
> +  EFI_PHYSICAL_ADDRESS                Address;
> +  UINTN                               ApSafeBufferSize;
> +  UINTN                               Index;
> +  EFI_GCD_MEMORY_SPACE_DESCRIPTOR     MemDesc;
> +  UINTN                               StackBase;
> 
>    SaveCpuMpData (CpuMpData);
> 
> @@ -301,6 +305,30 @@ InitMpGlobalData (
>      return;
>    }
> 
> +  if (PcdGetBool (PcdCpuStackGuard)) {
> +    //
> +    // One extra page at the bottom of the stack is needed for Guard page.
> +    //
> +    if (CpuMpData->CpuApStackSize <= EFI_PAGE_SIZE) {
> +      DEBUG ((DEBUG_ERROR, "PcdCpuApStackSize is not big enough for Stack
> Guard!\n"));
> +      ASSERT (FALSE);
> +    }
> +
> +    for (Index = 0; Index < CpuMpData->CpuCount; ++Index) {
> +      StackBase = CpuMpData->Buffer + Index * CpuMpData->CpuApStackSize;
> +
> +      Status = gDS->GetMemorySpaceDescriptor (StackBase, &MemDesc);
> +      ASSERT_EFI_ERROR (Status);
> +
> +      Status = gDS->SetMemorySpaceAttributes (
> +                      StackBase,
> +                      EFI_PAGES_TO_SIZE (1),
> +                      MemDesc.Attributes | EFI_MEMORY_RP
> +                      );
> +      ASSERT_EFI_ERROR (Status);
> +    }
> +  }
> +
>    //
>    // Avoid APs access invalid buffer data which allocated by BootServices,
>    // so we will allocate reserved data for AP loop code. We also need to
> --
> 2.15.1.windows.2
> 
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