Re: [PATCH 05/16] efi: Add EFI_SECURE_BOOT bit

[Ard Biesheuvel]

On 16 November 2016 at 21:47, David Howells <dhowells@xxxxxxxxxx> wrote:
> From: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
>
> UEFI machines can be booted in Secure Boot mode.  Add a EFI_SECURE_BOOT bit
> for use with efi_enabled.
>
> Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> ---
>
>  arch/x86/kernel/setup.c |    1 +
>  include/linux/efi.h     |    1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 9521acce8378..539f29587712 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1164,6 +1164,7 @@ void __init setup_arch(char **cmdline_p)
>         if (boot_params.secure_boot &&
>             IS_ENABLED(CONFIG_EFI_SECURE_BOOT_LOCK_DOWN)) {
>                 lock_kernel_down();
> +               set_bit(EFI_SECURE_BOOT, &efi.flags);

Why is this x86 only? And why is this bit only set if
CONFIG_EFI_SECURE_BOOT_LOCK_DOWN is enabled?

>                 pr_info("Secure boot enabled\n");
>         }
>
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 11372fb8784c..5d7fb3e3400b 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -1079,6 +1079,7 @@ 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
>  /*
>
> --
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