linux-kernel - Re: [patch V2 19/28] x86/process: Consolidate and simplify switch_to

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Date:   Mon, 26 Nov 2018 19:30:24 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jiri Kosina <jkosina@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Casey Schaufler <casey.schaufler@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Jon Masters <jcm@...hat.com>,
        Waiman Long <longman9394@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dave Stewart <david.c.stewart@...el.com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [patch V2 19/28] x86/process: Consolidate and simplify
 switch_to_xtra() code

On Sun, Nov 25, 2018 at 07:33:47PM +0100, Thomas Gleixner wrote:
> Move the conditional invocation of __switch_to_xtra() into an inline
> function so the logic can be shared between 32 and 64 bit.
> 
> Remove the handthrough of the TSS pointer and retrieve the pointer directly

s/handthrough/passing/

I guess.

> in the bitmap handling function. Use this_cpu_ptr() instead of the
> per_cpu() indirection.
>
> This is a preparatory change so integration of conditional indirect branch
> speculation optimization happens only in one place.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/x86/include/asm/switch_to.h |    3 ---
>  arch/x86/kernel/process.c        |   12 +++++++-----
>  arch/x86/kernel/process.h        |   24 ++++++++++++++++++++++++
>  arch/x86/kernel/process_32.c     |   10 +++-------
>  arch/x86/kernel/process_64.c     |   10 +++-------
>  5 files changed, 37 insertions(+), 22 deletions(-)

...

> --- /dev/null
> +++ b/arch/x86/kernel/process.h
> @@ -0,0 +1,24 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Code shared between 32 and 64 bit

checkpatch mutters here too:

WARNING: Missing or malformed SPDX-License-Identifier tag in line 1
#105: FILE: arch/x86/kernel/process.h:1:
+// SPDX-License-Identifier: GPL-2.0

I guess you want /* comments.

-- 
Regards/Gruss,
    Boris.

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