Re: [PATCH v3 0/4] Enable BTI support in memory attributes table

["Marvin Häuser" <mhaeuser@posteo.de>]

FWIW, Reviewed-by: Marvin Häuser <mhaeuser@posteo.de>

An off-topic remark, but I find it ominous that when adding a hack like the DllCharacteristicsEx debug entry, the opportunity is not used to turn it into something that can be expanded in the future without introducing yet another hack like this (I know 31 more Bits look plenty now, but if an address, offset, or size will be needed… ouch).

Best regards,
Marvin

> On 4. Apr 2023, at 17:40, Ard Biesheuvel <ardb@kernel.org> wrote:
> Implement version 2 of the memory attributes table, which now contains a
> flag informing the OS whether or not code regions may be mapped with CFI
> mitigations such as IBT or BTI enabled.
> 
> This series covers the remaining parts after the AArch64 specific
> changes were merged:
> 
> - Update the BaseTools to emit the appropriate PE/COFF annotation when a
>  BTI/IBT compatible ELF executable is converted to PE/COFF
> - Take this PE/COFF annotation into account when populating the memory
>  attributes table in the DXE core
> 
> TODO:
> - X64 changes to make the code IBT compatible and emit the ELF note
> - Figure out how to generate such executables with native PE toolchains
> - Implement BTI/IBT enforcement at boot time - this is something I
>  intend to look into next.
> 
> Can be tested with the CLANG38 toolchain (both Clang compiler and LLD
> linker, version 3.8 or newer) with the following build options.
> 
> [BuildOptions]
>  GCC:*_*_AARCH64_PP_FLAGS = -mbranch-protection=bti
>  GCC:*_*_AARCH64_CC_FLAGS = -mbranch-protection=bti
>  GCC:*_*_AARCH64_DLINK_FLAGS = -fuse-ld=lld -Wl,--no-relax,--no-pie,-z,bti-report=error
> 
> Changes since v2:
> - increase DllCharacteristicsEx field to 4 bytes
> - add Oliver's Rb
> 
> If no comments or objections have been raised by the end of the week, I
> will go ahead and merge this - thanks.
> 
> Cc: Michael Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Michael Kubacki <michael.kubacki@microsoft.com>
> Cc: Sean Brogan <sean.brogan@microsoft.com>
> Cc: Rebecca Cran <quic_rcran@quicinc.com>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> Cc: Taylor Beebe <t@taylorbeebe.com>
> Cc: Marvin Häuser <mhaeuser@posteo.de>
> Cc: Bob Feng <bob.c.feng@intel.com>
> Cc: Oliver Smith-Denny <osde@linux.microsoft.com>
> 
> Ard Biesheuvel (4):
>  BaseTools/GenFw: Parse IBT/BTI support status from ELF note
>  BaseTools/GenFw: Add DllCharacteristicsEx field to debug data
>  MdePkg/PeCoffLib: Capture DLL characteristics fields in image context
>  MdeModulePkg: Enable forward edge CFI in mem attributes table
> 
> BaseTools/Source/C/GenFw/Elf64Convert.c               | 104 +++++++++++++++++---
> BaseTools/Source/C/GenFw/GenFw.c                      |   3 +-
> BaseTools/Source/C/GenFw/elf_common.h                 |   9 ++
> BaseTools/Source/C/Include/IndustryStandard/PeImage.h |  13 ++-
> MdeModulePkg/Core/Dxe/DxeMain.h                       |   2 +
> MdeModulePkg/Core/Dxe/Image/Image.c                   |  10 ++
> MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c    |   8 +-
> MdePkg/Include/IndustryStandard/PeImage.h             |  13 ++-
> MdePkg/Include/Library/PeCoffLib.h                    |   6 ++
> MdePkg/Library/BasePeCoffLib/BasePeCoff.c             |  46 ++++++---
> 10 files changed, 186 insertions(+), 28 deletions(-)
> 
> -- 
> 2.39.2