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Subject[PATCH v9 00/10] efi/firmware/platform-x86: Add EFI embedded fw support
Hi All,

Here is v9 of my patch-set to add support for EFI embedded fw to the kernel.

The main new feature in this version is the addition of some selftests for
the new firmware_request_platform api (patch 5 and 6, both new). My plan
was to send the patches adding the selftests out as a follow up series.

But during unrelated testing of my personal tree I found a small but nasty
bug in the "efi: Add embedded peripheral firmware support" patch, the minor
refactoring done in v8 exposed a bug which causes a hard crash on boot for
devices which have a DMI match in the touchscreen_dmi_table but do not use
EFI-embedded fw, this is fixed in this new version.

Assuming the 2 new patches adding the selftests are ok, I believe that
this series is ready for merging now. I believe it would be best to merge
patches 1-8 through Greg's driver-core tree where firmware-loader changes go.
The non firmware patches already have Acked-by-s from the maintainers of
the EFI/input trees.

Patches 9-10 touch a quirks file under drivers/platform/x86 which sees
multipe updates each cycle. So my proposal is that once 1-8 has landed
Greg creates an immutable branch with those changes and then
Andy and/or Darren can merge in that branch and then apply 9 and 10.



Changes in v9:
- Add 2 new patches adding selftests
- At least touchscreen_dmi.c uses the same dmi_table for its own private
data and the fw_desc structs, putting the fw_desc struct first in the
data driver_data points to so that the dmi_table can be shared with
efi_check_for_embedded_firmwares(). But not all entries there have
embedded-fw so in some cases the fw_desc is empty (zero-ed out).
This can lead to a possible crash because fw_desc->length now is
less then 8, so if the segment size is close enough to a multiple of the
page_size, then the memcmp to check the prefix my segfault. Crashing the
machine. v9 checks for and skips these empty fw_desc entries avoiding this.
- Add static inline wrapper for firmware_request_platform() to firmware.h,
for when CONFIG_FW_LOADER is not set

Changes in v8:
- Add pr_warn if there are mode then EFI_DEBUGFS_MAX_BLOBS boot service segments
- Document how the EFI debugfs boot_service_code? files can be used to check for
embedded firmware
- Properly deal with the case of an EFI segment being smaller then the fw we
are looking for
- Log a warning when efi_get_embedded_fw get called while we did not (yet)
check for embedded firmwares
- Only build fallback_platform.c if CONFIG_EFI_EMBEDDED_FIRMWARE is defined,
otherwise make firmware_fallback_platform() a static inline stub

Changes in v7:
- Split drivers/firmware/efi and drivers/base/firmware_loader changes into
2 patches
- Use new, standalone, lib/crypto/sha256.c code
- Address kdoc comments from Randy Dunlap
- Add new FW_OPT_FALLBACK_PLATFORM flag and firmware_request_platform()
_request_firmware() wrapper, as requested by Luis R. Rodriguez
- Stop using "efi-embedded-firmware" device-property, now that drivers need to
use the new firmware_request_platform() to enable fallback to a device fw
copy embedded in the platform's main firmware, we no longer need a property
on the device to trigger this behavior
- Use security_kernel_load_data instead of calling
security_kernel_read_file with a NULL file pointer argument
- Move the docs to Documentation/driver-api/firmware/fallback-mechanisms.rst
- Document the new firmware_request_platform() function in
- Add 2 new patches for the silead and chipone-icn8505 touchscreen drivers
to use the new firmware_request_platform() method
- Rebased on top of 5.4-rc1

Changes in v6:
-Rework code to remove casts from if (prefix == mem) comparison
-Use SHA256 hashes instead of crc32 sums
-Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
-Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
to check if this is allowed before looking at EFI embedded fw
-Document why we are not using the PI Firmware Volume protocol

Changes in v5:

Changes in v4:
-Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
UEFI proper, so the EFI maintainers don't want us referring people to it
-Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
-Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
in firmware_loader/main.c
-Properly call security_kernel_post_read_file() on the firmware returned
by efi_get_embedded_fw() to make sure that we are allowed to use it

Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
fw support if this is set. This is an invisible option which should be
selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
from the efi-embedded-fw code, instead drivers using this are expected to
export a dmi_system_id array, with each entries' driver_data pointing to a
efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
this avoids us messing with the EFI memmap and avoids the need to make
changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
is set

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