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linux/drivers/firmware/efi/Kconfig
Hans de Goede f0df68d5ba efi: Add embedded peripheral firmware support 
Just like with PCI options ROMs, which we save in the setup_efi_pci*
functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself
sometimes may contain data which is useful/necessary for peripheral drivers
to have access to.

Specifically the EFI code may contain an embedded copy of firmware which
needs to be (re)loaded into the peripheral. Normally such firmware would be
part of linux-firmware, but in some cases this is not feasible, for 2
reasons:

1) The firmware is customized for a specific use-case of the chipset / use
with a specific hardware model, so we cannot have a single firmware file
for the chipset. E.g. touchscreen controller firmwares are compiled
specifically for the hardware model they are used with, as they are
calibrated for a specific model digitizer.

2) Despite repeated attempts we have failed to get permission to
redistribute the firmware. This is especially a problem with customized
firmwares, these get created by the chip vendor for a specific ODM and the
copyright may partially belong with the ODM, so the chip vendor cannot
give a blanket permission to distribute these.

This commit adds support for finding peripheral firmware embedded in the
EFI code and makes the found firmware available through the new
efi_get_embedded_fw() function.

Support for loading these firmwares through the standard firmware loading
mechanism is added in a follow-up commit in this patch-series.

Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end
of start_kernel(), just before calling rest_init(), this is on purpose
because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for
early_memremap(), so the check must be done after mm_init(). This relies
on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services()
is called, which means that this will only work on x86 for now.

Reported-by: Dave Olsthoorn <dave@bewaar.me>
Suggested-by: Peter Jones <pjones@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200115163554.101315-3-hdegoede@redhat.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-03-03 10:28:00 +01:00

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# SPDX-License-Identifier: GPL-2.0-only
menu "EFI (Extensible Firmware Interface) Support"
depends on EFI
config EFI_VARS
tristate "EFI Variable Support via sysfs"
depends on EFI
default n
help
If you say Y here, you are able to get EFI (Extensible Firmware
Interface) variable information via sysfs. You may read,
write, create, and destroy EFI variables through this interface.
Note that using this driver in concert with efibootmgr requires
at least test release version 0.5.0-test3 or later, which is
available from:
<http://linux.dell.com/efibootmgr/testing/efibootmgr-0.5.0-test3.tar.gz>
Subsequent efibootmgr releases may be found at:
<http://github.com/vathpela/efibootmgr>
config EFI_ESRT
bool
depends on EFI && !IA64
default y
config EFI_VARS_PSTORE
tristate "Register efivars backend for pstore"
depends on EFI_VARS && PSTORE
default y
help
Say Y here to enable use efivars as a backend to pstore. This
will allow writing console messages, crash dumps, or anything
else supported by pstore to EFI variables.
config EFI_VARS_PSTORE_DEFAULT_DISABLE
bool "Disable using efivars as a pstore backend by default"
depends on EFI_VARS_PSTORE
default n
help
Saying Y here will disable the use of efivars as a storage
backend for pstore by default. This setting can be overridden
using the efivars module's pstore_disable parameter.
config EFI_RUNTIME_MAP
bool "Export efi runtime maps to sysfs"
depends on X86 && EFI && KEXEC_CORE
default y
help
Export efi runtime memory maps to /sys/firmware/efi/runtime-map.
That memory map is used for example by kexec to set up efi virtual
mapping the 2nd kernel, but can also be used for debugging purposes.
See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
config EFI_FAKE_MEMMAP
bool "Enable EFI fake memory map"
depends on EFI && X86
default n
help
Saying Y here will enable "efi_fake_mem" boot option.
By specifying this parameter, you can add arbitrary attribute
to specific memory range by updating original (firmware provided)
EFI memmap.
This is useful for debugging of EFI memmap related feature.
e.g. Address Range Mirroring feature.
config EFI_MAX_FAKE_MEM
int "maximum allowable number of ranges in efi_fake_mem boot option"
depends on EFI_FAKE_MEMMAP
range 1 128
default 8
help
Maximum allowable number of ranges in efi_fake_mem boot option.
Ranges can be set up to this value using comma-separated list.
The default value is 8.
config EFI_SOFT_RESERVE
bool "Reserve EFI Specific Purpose Memory"
depends on EFI && EFI_STUB && ACPI_HMAT
default ACPI_HMAT
help
On systems that have mixed performance classes of memory EFI
may indicate specific purpose memory with an attribute (See
EFI_MEMORY_SP in UEFI 2.8). A memory range tagged with this
attribute may have unique performance characteristics compared
to the system's general purpose "System RAM" pool. On the
expectation that such memory has application specific usage,
and its base EFI memory type is "conventional" answer Y to
arrange for the kernel to reserve it as a "Soft Reserved"
resource, and set aside for direct-access (device-dax) by
default. The memory range can later be optionally assigned to
the page allocator by system administrator policy via the
device-dax kmem facility. Say N to have the kernel treat this
memory as "System RAM" by default.
If unsure, say Y.
config EFI_PARAMS_FROM_FDT
bool
help
Select this config option from the architecture Kconfig if
the EFI runtime support gets system table address, memory
map address, and other parameters from the device tree.
config EFI_RUNTIME_WRAPPERS
bool
config EFI_ARMSTUB
bool
config EFI_ARMSTUB_DTB_LOADER
bool "Enable the DTB loader"
depends on EFI_ARMSTUB
default y
help
Select this config option to add support for the dtb= command
line parameter, allowing a device tree blob to be loaded into
memory from the EFI System Partition by the stub.
If the device tree is provided by the platform or by
the bootloader this option may not be needed.
But, for various development reasons and to maintain existing
functionality for bootloaders that do not have such support
this option is necessary.
config EFI_BOOTLOADER_CONTROL
tristate "EFI Bootloader Control"
depends on EFI_VARS
default n
---help---
This module installs a reboot hook, such that if reboot() is
invoked with a string argument NNN, "NNN" is copied to the
"LoaderEntryOneShot" EFI variable, to be read by the
bootloader. If the string matches one of the boot labels
defined in its configuration, the bootloader will boot once
to that label. The "LoaderEntryRebootReason" EFI variable is
set with the reboot reason: "reboot" or "shutdown". The
bootloader reads this reboot reason and takes particular
action according to its policy.
config EFI_CAPSULE_LOADER
tristate "EFI capsule loader"
depends on EFI
help
This option exposes a loader interface "/dev/efi_capsule_loader" for
users to load EFI capsules. This driver requires working runtime
capsule support in the firmware, which many OEMs do not provide.
Most users should say N.
config EFI_CAPSULE_QUIRK_QUARK_CSH
bool "Add support for Quark capsules with non-standard headers"
depends on X86 && !64BIT
select EFI_CAPSULE_LOADER
default y
help
Add support for processing Quark X1000 EFI capsules, whose header
layout deviates from the layout mandated by the UEFI specification.
config EFI_TEST
tristate "EFI Runtime Service Tests Support"
depends on EFI
default n
help
This driver uses the efi.<service> function pointers directly instead
of going through the efivar API, because it is not trying to test the
kernel subsystem, just for testing the UEFI runtime service
interfaces which are provided by the firmware. This driver is used
by the Firmware Test Suite (FWTS) for testing the UEFI runtime
interfaces readiness of the firmware.
Details for FWTS are available from:
<https://wiki.ubuntu.com/FirmwareTestSuite>
Say Y here to enable the runtime services support via /dev/efi_test.
If unsure, say N.
config APPLE_PROPERTIES
bool "Apple Device Properties"
depends on EFI_STUB && X86
select EFI_DEV_PATH_PARSER
select UCS2_STRING
help
Retrieve properties from EFI on Apple Macs and assign them to
devices, allowing for improved support of Apple hardware.
Properties that would otherwise be missing include the
Thunderbolt Device ROM and GPU configuration data.
If unsure, say Y if you have a Mac. Otherwise N.
config RESET_ATTACK_MITIGATION
bool "Reset memory attack mitigation"
depends on EFI_STUB
help
Request that the firmware clear the contents of RAM after a reboot
using the TCG Platform Reset Attack Mitigation specification. This
protects against an attacker forcibly rebooting the system while it
still contains secrets in RAM, booting another OS and extracting the
secrets. This should only be enabled when userland is configured to
clear the MemoryOverwriteRequest flag on clean shutdown after secrets
have been evicted, since otherwise it will trigger even on clean
reboots.
config EFI_RCI2_TABLE
bool "EFI Runtime Configuration Interface Table Version 2 Support"
depends on X86 || COMPILE_TEST
help
Displays the content of the Runtime Configuration Interface
Table version 2 on Dell EMC PowerEdge systems as a binary
attribute 'rci2' under /sys/firmware/efi/tables directory.
RCI2 table contains BIOS HII in XML format and is used to populate
BIOS setup page in Dell EMC OpenManage Server Administrator tool.
The BIOS setup page contains BIOS tokens which can be configured.
Say Y here for Dell EMC PowerEdge systems.
config EFI_DISABLE_PCI_DMA
bool "Clear Busmaster bit on PCI bridges during ExitBootServices()"
help
Disable the busmaster bit in the control register on all PCI bridges
while calling ExitBootServices() and passing control to the runtime
kernel. System firmware may configure the IOMMU to prevent malicious
PCI devices from being able to attack the OS via DMA. However, since
firmware can't guarantee that the OS is IOMMU-aware, it will tear
down IOMMU configuration when ExitBootServices() is called. This
leaves a window between where a hostile device could still cause
damage before Linux configures the IOMMU again.
If you say Y here, the EFI stub will clear the busmaster bit on all
PCI bridges before ExitBootServices() is called. This will prevent
any malicious PCI devices from being able to perform DMA until the
kernel reenables busmastering after configuring the IOMMU.
This option will cause failures with some poorly behaved hardware
and should not be enabled without testing. The kernel commandline
options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma"
may be used to override this option.
endmenu
config EFI_EMBEDDED_FIRMWARE
bool
depends on EFI
select CRYPTO_LIB_SHA256
config UEFI_CPER
bool
config UEFI_CPER_ARM
bool
depends on UEFI_CPER && ( ARM || ARM64 )
default y
config UEFI_CPER_X86
bool
depends on UEFI_CPER && X86
default y
config EFI_DEV_PATH_PARSER
bool
depends on ACPI
default n
config EFI_EARLYCON
def_bool y
depends on SERIAL_EARLYCON && !ARM && !IA64
select FONT_SUPPORT
select ARCH_USE_MEMREMAP_PROT
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