Re: [PATCH 6/6] efi: Add EFI_SECURE_BOOT bit [ver #2]

Lukas Wunner
2016-11-23T09:27:35Z

On Wed, Nov 23, 2016 at 12:23:12AM +0000, David Howells wrote:
> From: Josh Boyer <jwboyer@fedoraproject.org>
>
> UEFI machines can be booted in Secure Boot mode. Add a EFI_SECURE_BOOT bit
> that can be passed to efi_enabled() to find out whether secure boot is
> enabled.
>
> This will be used by the SysRq+x handler, registered by the x86 arch, to find
> out whether secure boot mode is enabled so that it can be disabled.
>
> Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> arch/x86/kernel/setup.c | 7 +++++++
> include/linux/efi.h | 1 +
> 2 files changed, 8 insertions(+)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 9c337b0e8ba7..522915d6de1f 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1160,6 +1160,13 @@ void __init setup_arch(char **cmdline_p)
>
> io_delay_init();
>
> +#ifdef CONFIG_EFI
> + if (boot_params.secure_boot) {
> + set_bit(EFI_SECURE_BOOT, &efi.flags);
> + pr_info("Secure boot enabled\n");
> + }
> +#endif
> +

Section 20 of Documentation/CodingStyle recommends IS_ENABLED()
instead of #ifdef. Also, CONFIG_EFI_STUB might be more apt than
CONFIG_EFI.

Thanks,

Lukas

> /*
> * Parse the ACPI tables for possible boot-time SMP configuration.
> */
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index ff01ad6f2823..d95bb9e69974 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -1066,6 +1066,7 @@ extern int __init efi_setup_pcdp_console(char *);
> #define EFI_ARCH_1 7 /* First arch-specific bit */
> #define EFI_DBG 8 /* Print additional debug info at runtime */
> #define EFI_NX_PE_DATA 9 /* Can runtime data regions be mapped non-executable? */
> +#define EFI_SECURE_BOOT 10 /* Are we in Secure Boot mode? */
>
> #ifdef CONFIG_EFI
> /*
>