linux-kernel - Re: [PATCH 3/4] x86/fpu: Make the EFI FPU calling convention explicit

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Message-ID: <20210118121327.GB30090@zn.tnic>
Date:   Mon, 18 Jan 2021 13:13:27 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     x86@...nel.org, LKML <linux-kernel@...r.kernel.org>,
        Krzysztof Mazur <krzysiek@...lesie.net>,
        Krzysztof Olędzki <ole@....pl>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 3/4] x86/fpu: Make the EFI FPU calling convention explicit

On Sun, Jan 17, 2021 at 10:20:40PM -0800, Andy Lutomirski wrote:
> EFI uses kernel_fpu_begin() to conform to the UEFI calling convention.
> This specifically requires initializing FCW, whereas no sane 64-bit kernel
> code should use legacy 387 operations that reference FCW.
> 
> Add KFPU_EFI to make this self-documenting, and use it in the EFI code.

I'd prefer if you slap a comment over the kernel_fpu_begin() calls in
efi instead of adding a separate define etc.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette