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Message-Id: <20070823165201.717ed62d.akpm@linux-foundation.org>
Date: Thu, 23 Aug 2007 16:52:01 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Jiri Kosina <jkosina@...e.cz>
Cc: Zan Lynx <zlynx@....org>, linux-kernel@...r.kernel.org,
Ingo Molnar <mingo@...e.hu>,
Roland McGrath <roland@...hat.com>,
Jakub Jelinek <jakub@...hat.com>
Subject: Re: 2.6.23-rc3-mm1 - memory layout change? - lost support for
MAP_32BIT? - mono crashes
On Thu, 23 Aug 2007 11:28:25 +0200 (CEST)
Jiri Kosina <jkosina@...e.cz> wrote:
> Handle MAP_32BIT flags properly in x86_64 flexmmap
>
> We need to handle MAP_32BIT flags of mmap() properly for 64bit
> applications with filexible mmap layout.
>
> This patch introduces x86_64-specific version of
> arch_get_unmapped_area_topdown() which differs from the generic one in
> handling of the MAP_32BIT flag -- when this flag is passed to mmap(), we
> stick back to the legacy layout for this particular mmap, which gives
> proper 32bit range.
>
arch/x86_64/kernel/sys_x86_64.c | 98 ++++++++++++++++++++++++++++++++++++++++
include/asm-x86_64/pgtable.h | 1
well that's another hunk of code for us to maintain and to slow all our
computers down.
It is quite unobvious to me that the whole pie-randomization thing is
worth merging. Why shouldn't we just drop the lot?
<looks at the changelog>
This patch is using mmap()'s randomization functionality in such a way
that it maps the main executable of (specially compiled/linked
-pie/-fpie) ET_DYN binaries onto a random address (in cases in which
mmap() is allowed to perform a randomization).
The code has been extraced from Ingo's exec-shield patch
http://people.redhat.com/mingo/exec-shield/
that certainly doesn't tell anyone why we should merge this code into Linux.
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