[PATCH v4 00/13] UEFI boot and runtime services support for 32-bit ARM

Ard Biesheuvel ard.biesheuvel at linaro.org
Mon Nov 30 04:28:14 PST 2015

This series adds support for booting the 32-bit ARM kernel directly from
UEFI firmware using a builtin UEFI stub. It mostly reuses refactored arm64
code, and the differences (primarily the PE/COFF header and entry point and
the efi_create_mapping() implementation) are split out into arm64 and ARM

Since I did not receive any further comments in reply to v3 from the people who
commented on v2, I think this series in now in sufficient shape to be pulled.
Note that patch #1 touches mm/memblock.c and include/linux/memblock.h, for which
get_maintainer.pl does not provide a maintainer, so it has been cc'ed to various
past editors of those files, and to the linux-mm mailing list.

Since the series affects both arm64 and ARM, it is up to the maintainers to let
me know how and when they wish to proceed with this. My suggestion would be to
send out pull request for patches #1 - #5 to the arm64 maintainer, and for the
whole series to the ARM maintainer. This should keep any conflicts on either
side confined to the respective maintainer tree, rather then propagating all the
way to -next.

For the result of regression testing against these patches, please refer to the
following links for build and boot reports (respectively) generated by
kernelci.org (thanks guys). 


Note that the above is regression testing only, as kernelci does not yet support
booting 32-bit ARM targets in EFI mode. This functionality has been verified
independently (on actual hardware) by Ryan Harkin <ryan.harkin at linaro.org>, who
has kindly given his Tested-by for the ARM patches in this series (#6 - #13)

Please find instructions for duplicating the EFI boot testing using QEMU at the
end of this email.

Changes since v3:
- rebased onto v4.4-rc3
- minor change in #13: use 'dram_base + MAX_UNCOMP_KERNEL_SIZE' as preferred
  base for the allocation that holds the relocated compressed kernel image
  (the former value of 0x0 is usually not covered by DRAM, resulting in the
  value above to be used anyway)
- added Reviewed-by from Matt Fleming
- added Tested-by from Ryan Harkin (#6 - #13)

Changes since v2:
- Some issues pointed out by Russell and Matt that were not introduced by this
  series but merely became apparent due to the code movement in patch #4 have
  been addressed in a separate 2-piece series I sent out this morning. This v3
  is rebased on top of those patches.
- Added a patch (#9) that adds support for creating non-global mappings. This
  addresses a concern raised by Russell in response to v2 where the use of
  global mappings combined with a flawed context switch and TBL flush sequence
  could result in memory corruption.
- Rebased onto v4.4-rc2

Changes since v1:
- The primary difference between this version and the first one is that all
  prerequisites have either been merged, dropped for now (early FDT handling)
  or folded into this series (MEMBLOCK_NOMAP). IOW, this series can be applied
  on top of v4.4-rc1 directly.
- Dropped handling of UEFI permission bits. The reason is that the UEFIv2.5
  approach (EFI_PROPERTIES_TABLE) is flawed, and will be replaced by something
  better in the next version of the spec.

Patch #1 adds support for the MEMBLOCK_NOMAP attribute to the generic memblock
code. Its purpose is to annotate memory regions as normal memory even if they
are removed from the kernel direct mapping.

Patch #2 implements MEMBLOCK_NOMAP support for arm64

Patch #3 updates the EFI init code to remove UEFI reserved regions and regions
used by runtime services from the kernel direct mapping

Patch #4 splits off most of arch/arm64/kernel/efi.c into arch agnostic files
arm-init.c and arm-runtime.c under drivers/firmware/efi.

Patch #5 refactors the code split off in patch #1 to isolate the arm64 specific
pieces, and change a couple of arm64-isms that ARM handles slightly differently.

Patch #6 enables the generic early_ioremap and early_memremap implementations
for ARM. It reuses the kmap fixmap region, which is not used that early anyway.

Patch #7 splits off the core functionality of create_mapping() into a new
function __create_mapping() that we can reuse for mapping UEFI runtime regions.

Patch #8 factors out the early_alloc() routine so we can invoke __create_mapping
using another (late) allocator.

Patch #9 adds support to __create_mapping() for creating non-global translation
table entries. (new in v3)

Patch #10 implements create_mapping_late() that uses a late allocator.

Patch #11 implements MEMBLOCK_NOMAP support for ARM

Patch #12 implements the UEFI support in the kernel proper to probe the UEFI
memory map and map the runtime services.

Patch #13 ties together all of the above, by implementing the UEFI stub, and
introducing the Kconfig symbols that allow all of this to be built.

Ard Biesheuvel (12):
  mm/memblock: add MEMBLOCK_NOMAP attribute to memblock memory table
  arm64: only consider memblocks with NOMAP cleared for linear mapping
  arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP
  arm64/efi: split off EFI init and runtime code for reuse by 32-bit ARM
  arm64/efi: refactor EFI init and runtime code for reuse by 32-bit ARM
  ARM: add support for generic early_ioremap/early_memremap
  ARM: split off core mapping logic from create_mapping
  ARM: factor out allocation routine from __create_mapping()
  ARM: add support for non-global kernel mappings
  ARM: implement create_mapping_late() for EFI use
  ARM: only consider memblocks with NOMAP cleared for linear mapping
  ARM: wire up UEFI init and runtime support

Roy Franz (1):
  ARM: add UEFI stub support

 arch/arm/Kconfig                          |  20 ++
 arch/arm/boot/compressed/Makefile         |   4 +-
 arch/arm/boot/compressed/efi-header.S     | 130 ++++++++
 arch/arm/boot/compressed/head.S           |  54 +++-
 arch/arm/boot/compressed/vmlinux.lds.S    |   7 +
 arch/arm/include/asm/Kbuild               |   1 +
 arch/arm/include/asm/efi.h                |  83 +++++
 arch/arm/include/asm/fixmap.h             |  29 +-
 arch/arm/include/asm/mach/map.h           |   2 +
 arch/arm/include/asm/mmu_context.h        |   2 +-
 arch/arm/kernel/Makefile                  |   1 +
 arch/arm/kernel/efi.c                     |  38 +++
 arch/arm/kernel/setup.c                   |  10 +-
 arch/arm/mm/init.c                        |   5 +-
 arch/arm/mm/ioremap.c                     |   9 +
 arch/arm/mm/mmu.c                         | 128 +++++---
 arch/arm64/include/asm/efi.h              |   9 +
 arch/arm64/kernel/efi.c                   | 334 +-------------------
 arch/arm64/mm/init.c                      |   2 +-
 arch/arm64/mm/mmu.c                       |   2 +
 drivers/firmware/efi/Makefile             |   4 +
 drivers/firmware/efi/arm-init.c           | 209 ++++++++++++
 drivers/firmware/efi/arm-runtime.c        | 135 ++++++++
 drivers/firmware/efi/efi.c                |   2 +
 drivers/firmware/efi/libstub/Makefile     |   9 +
 drivers/firmware/efi/libstub/arm-stub.c   |   4 +-
 drivers/firmware/efi/libstub/arm32-stub.c |  85 +++++
 include/linux/memblock.h                  |   8 +
 mm/memblock.c                             |  28 ++
 29 files changed, 986 insertions(+), 368 deletions(-)
 create mode 100644 arch/arm/boot/compressed/efi-header.S
 create mode 100644 arch/arm/include/asm/efi.h
 create mode 100644 arch/arm/kernel/efi.c
 create mode 100644 drivers/firmware/efi/arm-init.c
 create mode 100644 drivers/firmware/efi/arm-runtime.c
 create mode 100644 drivers/firmware/efi/libstub/arm32-stub.c

Testing instructions

1. Download a prebuilt firmware binary:

2. Unzip it
gunzip QEMU_EFI.img.gz

3. Download a prebuilt kernel binary (non-LPAE or LPAE, respectively):

4. Run it
qemu-system-arm -M virt -m 512 -nographic \
	-bios QEMU_EFI.img -kernel zImage \
	-append 'earlycon efi=debug console=ttyAMA0'

(Ctrl-A Ctrl-X to quit)

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