[PATCH v4 0/7] MdeModulePkg: add support for dispatching foreign arch PE/COFF images

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

Add the basic plumbing to DXE core, the PCI bus driver and the boot manager
to allow PE/COFF images to be dispatched that target an architecture that is
not native for the platform, but which is supported by one of potentially
several available emulators.

One implementation of such an emulator can be found here:
https://github.com/ardbiesheuvel/X86EmulatorPkg/tree/upstream-v4

This also allows us to get rid of the special treatment of EBC images in
core code. Instead, the EbcDxe driver is augmented with an implementation
of the EDK2 PE/COFF image emulator protocol so that internal knowledge of
how EBC is implemented (I-cache flushing, thunks) is removed from the DXE
core.

Changes since v3:
- Simplify the handling of option ROMs and Driver#### images, by simply
  deferring to the LoadImage() boot service to decide whether an image
  can be supported or not - this removes some redundant checks from the
  BDS layer and the PCI bus driver.
- Move the machine type supported by the emulator into the protocol struct,
  so we can optimize away calls into the emulator for each image loaded.
  Instead, the LoadImage() code will only invoke the IsSupported() method for
  images that are known to have a matching machine type.

Note that I have considered, but ultimately dismissed the suggestion to
register and unregister emulators via a new protocol. The main issue is
that registering and unregistering struct containing sets of function
pointers is awfully similar to managing a protocol database, and we already
have the code to do that in EDK2.

So instead, I have removed all the code that iterates over a handle buffer
of emu protocols and invokes each one to see if it will support the image.
Instead, this is all done by CoreLoadImage().

Changes since v2:
- incorporate feedback from Andrew Fish (delivered in person):
  * pass a device path into the IsImageSupported() protocol method so that an
    implementation can blacklist or whitelist certain devices, or implement
    other policies that depend on the device where the driver originated
  * allow the emulator to supersede the native loading of the image - this
    permits things like X86 on X86 emulators for security sandboxing or debug

Changes since v1:
- subsume the EBC handling into the EDK2 emulator protocol and abstract
  away from EBC specifics in core code.
- allow multiple emulator implementations to co-exist
- incorporate Star's review feedback

Cc: Vincent Zimmer <vincent.zimmer@intel.com>
Cc: Brian Richardson <brian.richardson@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Steven Shi <steven.shi@intel.com>

Ard Biesheuvel (7):
  MdeModulePkg: introduce PE/COFF image emulator protocol
  MdeModulePkg/DxeCore: invoke the emulator protocol for foreign images
  MdeModulePkg/PciBusDxe: dispatch option ROMs for foreign architectures
  MdeModulePkg/UefiBootManagerLib: allow foreign Driver#### images
  MdeModulePkg/EbcDxe: implement the PE/COFF emulator protocol
  MdePkg/UefiBaseType.h: treat EBC as a non-native machine type
  MdeModulePkg/DxeCore: remove explicit EBC handling

 .../Bus/Pci/PciBusDxe/PciOptionRomSupport.c   |   7 -
 MdeModulePkg/Core/Dxe/DxeMain.h               |   6 +-
 MdeModulePkg/Core/Dxe/DxeMain.inf             |   2 +-
 MdeModulePkg/Core/Dxe/Image/Image.c           | 183 ++++++++++++------
 .../Include/Protocol/PeCoffImageEmulator.h    | 107 ++++++++++
 .../Library/UefiBootManagerLib/BmLoadOption.c |   6 +-
 MdeModulePkg/MdeModulePkg.dec                 |   4 +
 MdeModulePkg/Universal/EbcDxe/EbcDebugger.inf |   3 +
 MdeModulePkg/Universal/EbcDxe/EbcDxe.inf      |   3 +
 MdeModulePkg/Universal/EbcDxe/EbcInt.c        | 123 ++++++++++++
 MdeModulePkg/Universal/EbcDxe/EbcInt.h        |   3 +
 MdePkg/Include/Uefi/UefiBaseType.h            |   6 +-
 12 files changed, 381 insertions(+), 72 deletions(-)
 create mode 100644 MdeModulePkg/Include/Protocol/PeCoffImageEmulator.h

-- 
2.17.1