linux-kernel - Re: [PATCH] x86: Set the NX-compatibility flag in the PE header

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Message-ID: <CAMj1kXFEGXnm_cz0AZUmQQd8dqAWUT=iNZk0eSqq34=BxiWwUA@mail.gmail.com>
Date:   Wed, 13 Apr 2022 19:48:17 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Peter Jones <pjones@...hat.com>
Cc:     Baskov Evgeniy <baskov@...ras.ru>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: Set the NX-compatibility flag in the PE header

On Tue, 29 Mar 2022 at 20:47, Peter Jones <pjones@...hat.com> wrote:
>
> Following Baskov Evgeniy's "Handle UEFI NX-restricted page tables"
> patches, it's safe to set this compatibility flag to let loaders know
> they don't need to make special accommodations for kernel to load if
> pre-boot NX is enabled.
>
> Signed-off-by: Peter Jones <pjones@...hat.com>

Thanks, I've queued this up.

> ---
>  arch/x86/boot/header.S | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
> index 6dbd7e9f74c..0352e4589ef 100644
> --- a/arch/x86/boot/header.S
> +++ b/arch/x86/boot/header.S
> @@ -163,7 +163,11 @@ extra_header_fields:
>         .long   0x200                           # SizeOfHeaders
>         .long   0                               # CheckSum
>         .word   IMAGE_SUBSYSTEM_EFI_APPLICATION # Subsystem (EFI application)
> +#ifdef CONFIG_DXE_MEM_ATTRIBUTES
> +       .word   IMAGE_DLL_CHARACTERISTICS_NX_COMPAT     # DllCharacteristics
> +#else
>         .word   0                               # DllCharacteristics
> +#endif
>  #ifdef CONFIG_X86_32
>         .long   0                               # SizeOfStackReserve
>         .long   0                               # SizeOfStackCommit
> --
> 2.35.1
>