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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Nadav Amit <namit@vmware.com>
Cc: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Edward Cree <ecree@solarflare.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>, Borislav Petkov <bp@alien8.de>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [RFC v2 0/6] x86: dynamic indirect branch promotion
Date: Thu, 3 Jan 2019 14:31:09 -0600
Message-ID: <20190103203109.cdck5kwck5gnkko7@treble> (raw)
In-Reply-To: <7FA580EA-9DEA-4813-8832-F1BE034A857C@vmware.com>

On Thu, Jan 03, 2019 at 06:30:08PM +0000, Nadav Amit wrote:
> > On Jan 3, 2019, at 10:10 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > 
> > On Mon, Dec 31, 2018 at 07:53:06PM +0000, Nadav Amit wrote:
> >>> On Dec 31, 2018, at 11:51 AM, Andy Lutomirski <luto@kernel.org> wrote:
> >>> 
> >>> On Sun, Dec 30, 2018 at 11:20 PM Nadav Amit <namit@vmware.com> wrote:
> >>>> This is a revised version of optpolines (formerly named retpolines) for
> >>>> dynamic indirect branch promotion in order to reduce retpoline overheads
> >>>> [1].
> >>> 
> >>> Some of your changelogs still call them "relpolines".
> >>> 
> >>> I have a crazy suggestion: maybe don't give them a cute name at all?
> >>> Where it's actually necessary to name them (like in a config option),
> >>> use a description like CONFIG_DYNAMIC_DEVIRTUALIZATION or
> >>> CONFIG_PATCH_INDIRECT_CALLS or something.
> > 
> > Cute or not, naming is important.
> > 
> > If you want a description instead of a name, it will be a challenge to
> > describe it in 2-3 words.
> > 
> > I have no idea what "dynamic devirtualization" means.
> > 
> > "Patch indirect calls" doesn't fully describe it either (and could be
> > easily confused with static calls and some other approaches).
> > 
> >> I’m totally fine with that (don’t turn me into a "marketing” guy). It was
> >> just a way to refer to the mechanism. I need more feedback about the more
> >> fundamental issues to go on.
> > 
> > Naming isn't marketing.  It's a real issue: it affects both usability
> > and code readability.
> 
> Well, allow me to be on the fence not this one.
> 
> I look for the path of least resistance. I think it would be easiest if I
> first manage to make Josh’s static calls to be less intrusive. For that, I
> try to add in the GCC plugin an attribute to annotate the function pointers
> whose calls should be promoted. However, I don’t manage to get the
> declaration from the call instruction's rtx. If anyone has a pointer on how
> it can be done, that’s would be very helpful.

Ok.  FYI, I'll be posting v3 in the next few days or so.

-- 
Josh

  reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-31  7:21 Nadav Amit
2018-12-31  7:21 ` [RFC v2 1/6] x86: introduce kernel restartable sequence Nadav Amit
2018-12-31 20:08   ` Andy Lutomirski
2018-12-31 21:12     ` Nadav Amit
2019-01-03 22:21   ` Andi Kleen
2019-01-03 22:29     ` Nadav Amit
2019-01-03 22:48       ` Andi Kleen
2019-01-03 22:52         ` Nadav Amit
2019-01-03 23:40           ` Andi Kleen
2019-01-03 23:56             ` Nadav Amit
2019-01-04  0:34   ` hpa
2018-12-31  7:21 ` [RFC v2 2/6] objtool: ignore instructions Nadav Amit
2018-12-31  7:21 ` [RFC v2 3/6] x86: patch indirect branch promotion Nadav Amit
2018-12-31  7:21 ` [RFC v2 4/6] x86: interface for accessing indirect branch locations Nadav Amit
2018-12-31  7:21 ` [RFC v2 5/6] x86: learning and patching indirect branch targets Nadav Amit
2018-12-31 20:05   ` Andy Lutomirski
2018-12-31 21:07     ` Nadav Amit
2018-12-31  7:21 ` [RFC v2 6/6] x86: outline optpoline Nadav Amit
2018-12-31 19:51 ` [RFC v2 0/6] x86: dynamic indirect branch promotion Andy Lutomirski
2018-12-31 19:53   ` Nadav Amit
2019-01-03 18:10     ` Josh Poimboeuf
2019-01-03 18:30       ` Nadav Amit
2019-01-03 20:31         ` Josh Poimboeuf [this message]
2019-01-03 22:18 ` Andi Kleen
2019-01-07 16:32   ` Peter Zijlstra
2019-01-08  7:47     ` Adrian Hunter
2019-01-08  9:25       ` Peter Zijlstra
2019-01-08 10:01         ` Adrian Hunter
2019-01-08 10:10           ` Peter Zijlstra
2019-01-08 17:27             ` Andi Kleen
2019-01-08 18:28               ` Nadav Amit
2019-01-08 19:01                 ` Peter Zijlstra
2019-01-08 20:47                   ` Nadav Amit
2019-01-08 20:53                     ` Andi Kleen
2019-01-09 10:35                     ` Peter Zijlstra
2019-08-29  8:23                       ` Tracing text poke / kernel self-modifying code (Was: Re: [RFC v2 0/6] x86: dynamic indirect branch promotion) Adrian Hunter
2019-08-29  8:53                         ` Peter Zijlstra
2019-08-29  9:40                           ` Adrian Hunter
2019-08-29 11:46                             ` Peter Zijlstra
2019-09-12  7:00                               ` Adrian Hunter
2019-09-12 12:17                                 ` hpa
2019-01-08 18:57               ` [RFC v2 0/6] x86: dynamic indirect branch promotion Peter Zijlstra

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