Re: [PATCH v2 0/4] Support non-stop mode in heap guard and null detection

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

Hi Laszlo,

Regards,
Jian

From: Laszlo Ersek [mailto:lersek@redhat.com]
Sent: Tuesday, August 21, 2018 10:28 PM
To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
Subject: Re: [edk2] [PATCH v2 0/4] Support non-stop mode in heap guard and null detection

On 08/21/18 05:05, Jian J Wang wrote:
>> v2 changes:
>>    fix GCC build error
>
> Background:
> Heap Guard and NULL Pointer Detection are very useful features to detect
> code flaw in EDK II. If an issue is detected, #PF exception will be
> triggered and the BIOS will enter into dead loop, which is the default
> behavior of exception handling. From QA perspective, this default behavior
> will block them to collect all tests result in reasonable time.
>
> Solution:
> This patch series update CpuDxe, PiSmmCpuDxeSmm and CpuExceptionHandlerLib
> to allow the code to continue execution after #PF. The mechanism behind it
> is the same as SMM Profile feature, in which a special #PF handler is
> registered to set the page causing #PF to be 'present' and setup single
> steop trap, then return the control back to the instruction accessing that
> page. Once the instruction is re-executed, a #DB is triggered and a special
> handler for it will be called to reset the page back to 'not-present'.
>
> Usage:
> The non-stop mode is enabled/disabled by BIT6 of following PCDs
>
>   gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask
>   gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask
>
> The default setting is 'disable'.
>
> BZ Tracker:
> https://bugzilla.tianocore.org/show_bug.cgi?id=1095
>
> OS Boot Validation:
>   Platform: OVMF
>   OS (x64): Fedora 26, Ubuntu 18.04, Windows 10, Windows 7
>
> Jian J Wang (4):
>   MdeModulePkg/MdeModulePkg.dec: add new settings for PCDs
>   UefiCpuPkg/CpuExceptionHandlerLib: Setup single step in #PF handler
>   UefiCpuPkg/CpuDxe: implement non-stop mode for uefi
>   UefiCpuPkg/PiSmmCpuDxeSmm: implement non-stop mode for SMM
>
>  MdeModulePkg/MdeModulePkg.dec                      |   4 +-
>  UefiCpuPkg/CpuDxe/CpuDxe.h                         |  39 +++
>  UefiCpuPkg/CpuDxe/CpuDxe.inf                       |   3 +
>  UefiCpuPkg/CpuDxe/CpuMp.c                          |  34 ++-
>  UefiCpuPkg/CpuDxe/CpuPageTable.c                   | 271 +++++++++++++++++++++
>  .../Ia32/ExceptionHandlerAsm.nasm                  |   7 +
>  .../Ia32/ExceptionTssEntryAsm.nasm                 |   4 +-
>  .../X64/ExceptionHandlerAsm.nasm                   |   4 +
>  UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c           |  43 ++--
>  UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/SmiException.nasm   |   3 +-
>  UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c             |  58 ++++-
>  UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.h             |  15 ++
>  UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfileInternal.h     |   6 +
>  UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c            |  43 ++--
>  14 files changed, 493 insertions(+), 41 deletions(-)
>


(1) This looks like a feature addition, so please include the BZ
reference (1095) on the following wiki page:

https://github.com/tianocore/tianocore.github.io/wiki/EDK-II-Release-Planning

(under "Proposed Features")

[Jian] Sure. I’ll add it.

(2) The general description should be moved (or copied) from this email
(v2 0/4) to patch #1 (v2 1/4). The cover letter is not captured in the
commit log, and I think there isn't going to be any other documentation
for the feature than the DEC file.

(Note that I'm not suggesting that you add the documentation to the DEC
file in patch #1 -- instead, the commit message on patch #1 should
contain it. Then people can find the commit from the DEC file with "git
blame", and read the description.)

[Jian] You’re right. I forgot this point. I’ll copy it. Thanks.

Thanks
Laszlo