linux-kernel - Re: [PATCH v8 09/21] x86/paravirt: Align paravirt thunk functions at 16-byte boundaries

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Message-ID: <CALCETrX4aBxf_apw8oqb_jM_NWp4mSa_8enP_zwF_DX01Dnsiw@mail.gmail.com>
Date:	Tue, 28 Jul 2015 08:23:04 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Pedro Alves <palves@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
	X86 ML <x86@...nel.org>, live-patching@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 09/21] x86/paravirt: Align paravirt thunk functions at
 16-byte boundaries

On Tue, Jul 28, 2015 at 7:47 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> Paravirt thunk functions aren't aligned, which can impact performance
> and is inconsistent with gcc-generated functions.
>
> Align them at 16-byte boundaries to be consistent with gcc functions.

IMO stackvalidate shouldn't warn about this.  We've discussed dropping
the alignment requirement entirely, since it seems to have little
benefit on modern CPUs.

--Andy
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