diff options
| author |   Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2018-07-11 11:40:38 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-07-16 00:43:12 +0200 |
| commit | 3d7ee348aa4127a7893c11261da9b76371a970e6 (patch) | |
| tree | b3dee7e3ebdf9d4ddce9cd259031fce35ed145e5 /drivers/firmware | |
| parent | efi: Remove the declaration of efi_late_init() as the function is unused (diff) | |
| download | linux-dev-3d7ee348aa4127a7893c11261da9b76371a970e6.tar.xz linux-dev-3d7ee348aa4127a7893c11261da9b76371a970e6.zip | |
efi/libstub/arm: Add opt-in Kconfig option for the DTB loader
There are various ways a platform can provide a device tree binary
to the kernel, with different levels of sophistication:
- ideally, the UEFI firmware, which is tightly coupled with the
platform, provides a device tree image directly as a UEFI
configuration table, and typically permits the contents to be
manipulated either via menu options or via UEFI environment
variables that specify a replacement image,
- GRUB for ARM has a 'devicetree' directive which allows a device
tree image to be loaded from any location accessible to GRUB, and
supersede the one provided by the firmware,
- the EFI stub implements a dtb= command line option that allows a
device tree image to be loaded from a file residing in the same
file system as the one the kernel image was loaded from.
The dtb= command line option was never intended to be more than a
development feature, to allow the other options to be implemented
in parallel. So let's make it an opt-in feature that is disabled
by default, but can be re-enabled at will.
Note that we already disable the dtb= command line option when we
detect that we are running with UEFI Secure Boot enabled.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Alexander Graf <agraf@suse.de>
Acked-by: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180711094040.12506-7-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/firmware/efi/libstub/arm-stub.c | 7 |
2 files changed, 16 insertions, 3 deletions
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 781a4a337557..d8e159feb573 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -87,6 +87,18 @@ config EFI_RUNTIME_WRAPPERS config EFI_ARMSTUB bool +config EFI_ARMSTUB_DTB_LOADER + bool "Enable the DTB loader" + depends on EFI_ARMSTUB + 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. + + The device tree is typically provided by the platform or by + the bootloader, so this option is mostly for development + purposes only. + config EFI_BOOTLOADER_CONTROL tristate "EFI Bootloader Control" depends on EFI_VARS diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 01a9d78ee415..c98b1856fc3d 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -202,9 +202,10 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure * boot is enabled if we can't determine its state. */ - if (secure_boot != efi_secureboot_mode_disabled && - strstr(cmdline_ptr, "dtb=")) { - pr_efi(sys_table, "Ignoring DTB from command line.\n"); + if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) || + secure_boot != efi_secureboot_mode_disabled) { + if (strstr(cmdline_ptr, "dtb=")) + pr_efi(sys_table, "Ignoring DTB from command line.\n"); } else { status = handle_cmdline_files(sys_table, image, cmdline_ptr, "dtb=", |