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Re: Creating aliases for memory ranges

From: Ángel González <keisial at gmail dot com>
To: Florian Weimer <fweimer at redhat dot com>
Cc: Maxim Kuvyrkov <maxim at kugelworks dot com>, libc-help at sourceware dot org
Date: Sat, 26 Oct 2013 14:20:30 +0200
Subject: Re: Creating aliases for memory ranges
Authentication-results: sourceware.org; auth=none
References: <50FFB8E6 dot 4010808 at redhat dot com> <77E174C8-B5EB-435F-A6AF-ED7C01D85A32 at kugelworks dot com> <5104301A dot 4070801 at gmail dot com> <52613D7F dot 30601 at redhat dot com>

On 18/10/13 15:54, Florian Weimer wrote:

On 01/26/2013 08:35 PM, Ángel González wrote:
Florian, you need to open a temporary file and map it twice (once ro and
the other rw). You can then unlink the file after opening. You can't
duplicate a mapping with no associated file.
I tried to map memory from /proc/self/map, but that doesn't work,either. I came up with the attached code instead. It has theadvantage that the memory area isn't backed by disk (if /dev/shm is ontmpfs), so it won't cause any pointless disk I/O.

Looks good. If you're interesed, there were some code and discussionabout that related to the executable pages must not be writable patchesand jit engines such as firefox.

References:
- Re: Creating aliases for memory ranges
  - From: Florian Weimer

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