Re: [PATCH 0/5] StandaloneMmPkg: make StMM core relocatable

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Hi Ard, 

Tested on QEMU with the op-tee patches i mentioned in my RFC [1]
Everything seems to work correctly


[1] https://edk2.groups.io/g/devel/message/60835

On Wed, Jun 10, 2020 at 10:17:35AM +0200, Ard Biesheuvel wrote:
> It is not always possible to deploy the standalone MM core in a way where
> the runtime address is known at build time. This does not matter for most
> modules, since they are relocated at dispatch time. However, for the MM
> core itself, it means we need to do some extra work to relocate the image
> in place if it ends up at a different offset than expected.
> 
> On AARCH64, the standalone MM stack is deployed inside a non-privileged
> secure world container which only has limited control over its memory
> mappings, and so we need to ensure that the executable code itself is
> free of absolute quantities that need to be fixed up. This is very similar
> to how shared libraries are constructed, given that pages can only be
> shared between processes if they are not modified, even by the dynamic
> loader. So we can use this support to emit the standaline MM core in a
> way that guarantees that the executable code does not need to modify
> itself (patch #4)
> 
> Patch #5 adds the actual code to perform the self relocation after the
> .data section has been made writable and non-executable. Note that the
> PE/COFF library code modifies the header in place, and so in the case
> where we need to perform the runtime relocation, we need to remap the
> header page writable and non-executable as well.
> 
> The remaining patches are optimizations and fixes I picked up along
> the way.
> 
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Sami Mujawar <sami.mujawar@arm.com>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> 
> Ard Biesheuvel (5):
>   MdePkg/BasePrintLib: avoid absolute addresses for error strings
>   StandaloneMmPkg/Core: fix bogus FV pointer in DEBUG string
>   StandaloneMmPkg/Core: add missing GUID reference
>   StandaloneMmPkg: generate position independent code for StMM core
>   StandaloneMmPkg/StandaloneMmCoreEntryPoint: relocate StMM core on the
>     fly
> 
>  StandaloneMmPkg/Core/StandaloneMmCore.inf                                               |  5 +++++
>  StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf       |  3 +++
>  StandaloneMmPkg/Include/Library/AArch64/StandaloneMmCoreEntryPoint.h                    |  2 ++
>  MdePkg/Library/BasePrintLib/PrintLibInternal.c                                          |  2 +-
>  StandaloneMmPkg/Core/Dispatcher.c                                                       |  2 +-
>  StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/SetPermissions.c             | 11 +++++++---
>  StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c | 22 ++++++++++++++++++++
>  7 files changed, 42 insertions(+), 5 deletions(-)
> 
> -- 
> 2.26.2
> 

Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>