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From: Alexander Popov <alex.popov@linux.com>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Laura Abbott <labbott@redhat.com>,
	xen-devel@lists.xenproject.org, dri-devel@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org,
	intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, dev@openvswitch.org,
	linux-kbuild@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	kernel-hardening@lists.openwall.com,
	Greg KH <gregkh@linuxfoundation.org>,
	Jann Horn <jannh@google.com>,
	William Kucharski <william.kucharski@oracle.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Edwin Zimmerman <edwin@211mainstreet.net>,
	Matthew Wilcox <willy@infradead.org>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Subject: Re: [PATCH 0/3] gcc-plugins: Introduce stackinit plugin
Date: Tue, 29 Jan 2019 03:12:24 +0300	[thread overview]
Message-ID: <874b8c23-068b-f8e7-2168-12947c06e145@linux.com> (raw)
In-Reply-To: <20190123110349.35882-1-keescook@chromium.org>

On 23.01.2019 14:03, Kees Cook wrote:
> This adds a new plugin "stackinit" that attempts to perform unconditional
> initialization of all stack variables

Hello Kees! Hello everyone!

I was curious about the performance impact of the initialization of all stack
variables. So I did a very brief test with this plugin on top of 4.20.5.

hackbench on Intel Core i7-4770 showed ~0.7% slowdown.
hackbench on Kirin 620 (ARM Cortex-A53 Octa-core 1.2GHz) showed ~1.3% slowdown.

This test involves the kernel scheduler and allocator. I can't say whether they
use stack aggressively. Maybe performance tests of other subsystems (e.g.
network subsystem) can show different numbers. Did you try?

I've heard a hypothesis that the initialization of all stack variables would
pollute CPU caches, which is critical for some types of computations. Maybe some
micro-benchmarks can disprove/confirm that?

Thanks!
Best regards,
Alexander

  parent reply	other threads:[~2019-01-29  0:12 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-23 11:03 Kees Cook
2019-01-23 11:03 ` [PATCH 1/3] treewide: Lift switch variables out of switches Kees Cook
2019-01-23 11:58   ` Greg KH
2019-01-23 12:09     ` Jann Horn
2019-01-23 12:12       ` Ard Biesheuvel
2019-01-23 13:21       ` William Kucharski
2019-01-23 14:17     ` [Intel-gfx] " Jani Nikula
2019-01-23 14:23       ` Jani Nikula
2019-01-23 14:47       ` Edwin Zimmerman
2019-01-23 15:46         ` Jani Nikula
2019-01-23 18:55           ` Kees Cook
2019-01-24  8:10             ` Greg KH
2019-01-23 19:18       ` Matthew Wilcox
2019-01-23 20:36         ` Kees Cook
2019-01-23 16:51   ` [Intel-wired-lan] " Jeff Kirsher
2019-01-24 12:58   ` Edwin Zimmerman
2019-01-23 11:03 ` [PATCH 2/3] gcc-plugins: Introduce stackinit plugin Kees Cook
2019-01-23 11:03 ` [PATCH 3/3] lib: Introduce test_stackinit module Kees Cook
2019-01-29  0:12 ` Alexander Popov [this message]
2019-02-12 17:54   ` [PATCH 0/3] gcc-plugins: Introduce stackinit plugin Kees Cook

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