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From: Thomas Gleixner <tglx@linutronix.de>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
	Wang Nan <wangnan0@huawei.com>,
	David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH v2] x86, mm: set NX across entire PMD at boot
Date: Sun, 16 Nov 2014 19:52:05 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.11.1411161947540.3909@nanos> (raw)
In-Reply-To: <CAE9FiQVAWYdZvq3QDn-=06QX0+H=RynSS+VVmvTyAaU1BECR_g@mail.gmail.com>

On Fri, 14 Nov 2014, Yinghai Lu wrote:

> On Fri, Nov 14, 2014 at 6:46 PM, Kees Cook <keescook@chromium.org> wrote:
> > On Fri, Nov 14, 2014 at 6:29 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> 
> >> should use attached one instead.
> >>
> >> 1. should use _brk_end instead of &end, as we only use partial of
> >>    brk.
> >> 2. [_brk_end, pm_end) page range is already converted. aka
> >>    is not wasted.
> >
> > Are you sure? For me, _brk_end isn't far enough:
> >
> > [    1.475572] all_end: 0xffffffff82df5000
> > [    1.476736] _brk_end: 0xffffffff82dd6000
> 
> Yes. _brk_end should be small then &_end.

Wrong. _brk_end can move up to _end, i.e. to __brk_limit.
 
But it's safe to use _brk_end when mark_rodata_ro() is called because
extend_brk() is gone already at that point.

Thanks,

	tglx

  parent reply	other threads:[~2014-11-16 18:52 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-14 20:45 Kees Cook
2014-11-15  1:29 ` Yinghai Lu
2014-11-15  2:29   ` Yinghai Lu
2014-11-15  2:46     ` Kees Cook
2014-11-15  3:38       ` Yinghai Lu
2014-11-15  9:43         ` Yinghai Lu
2014-11-16 21:26           ` Thomas Gleixner
2014-11-17  3:30             ` Yinghai Lu
2014-11-16 18:52         ` Thomas Gleixner [this message]
2014-11-17  3:26           ` Yinghai Lu
2014-11-16 23:44       ` Thomas Gleixner
2014-11-17  4:00         ` Yinghai Lu
2014-11-17 20:27         ` Kees Cook
2014-11-17 20:32           ` Russell King - ARM Linux
2014-11-17 20:43             ` Kees Cook
2014-11-18  7:39           ` Yinghai Lu
2014-11-18 17:11       ` Thomas Gleixner
2014-11-15  3:06   ` Kees Cook
2014-11-15  3:34     ` Yinghai Lu

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