From: robherring2@gmail.com (Rob Herring)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] ARM: topdown mmap support
Date: Mon, 14 Nov 2011 12:05:54 -0600 [thread overview]
Message-ID: <4EC15882.7070909@gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1111141237080.3307@xanadu.home>
On 11/14/2011 11:41 AM, Nicolas Pitre wrote:
> On Mon, 7 Nov 2011, Rob Herring wrote:
>
>> From: Rob Herring <rob.herring@calxeda.com>
>>
>> Similar to other architectures, this adds topdown mmap support in user
>> process address space allocation policy. This allows mmap sizes greater
>> than 2GB. This support is largely copied from MIPS and the generic
>> implementations.
>>
>> The address space randomization is moved into arch_pick_mmap_layout.
>
> This is a problem by effectively weakening the randomization greatly.
> Now you get a random starting point but all mmaps are otherwise fixed
> relative to each other, whereas you had random distances between each
> mmaps before.
>
You mean within a single process the mmap's are not randomized? Couldn't
that end up wasting a lot of virtual space if you have a lot of mmaps?
It is aligned with other arch's and the generic implementation. The
generic implementation doesn't even do randomization for legacy layouts.
Rob
next prev parent reply other threads:[~2011-11-14 18:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-07 23:43 [PATCH 1/2] ARM: use cache type functions for arch_get_unmapped_area Rob Herring
2011-11-07 23:43 ` [PATCH 2/2] ARM: topdown mmap support Rob Herring
2011-11-14 17:41 ` Nicolas Pitre
2011-11-14 18:05 ` Rob Herring [this message]
2011-11-14 18:22 ` Nicolas Pitre
2011-11-15 23:02 ` Rob Herring
2011-11-16 23:45 ` Nicolas Pitre
2011-11-14 17:36 ` [PATCH 1/2] ARM: use cache type functions for arch_get_unmapped_area Nicolas Pitre
2011-11-14 20:27 ` Will Deacon
2011-11-14 20:36 ` Rob Herring
2011-11-15 23:37 ` Rob Herring
2011-11-16 9:48 ` Will Deacon
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