linux-kernel - Re: [PATCH 0/12] Pass MAP_FIXED down to get_unmapped

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 12 Apr 2007 10:56:29 +0800
From:	"Wu, Bryan" <bryan.wu@...log.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Memory Management <linux-mm@...ck.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/12] Pass MAP_FIXED down to get_unmapped_area

On Thu, 2007-04-12 at 12:20 +1000, Benjamin Herrenschmidt wrote:
> This is a "first step" as there are still cleanups to be done in various
> areas touched by that code but I think it's probably good to go as is and
> at least enables me to implement what I need for PowerPC.
> 
> (Andrew, this is also candidate for 2.6.22 since I haven't had any real
> objection, mostly suggestion for improving further, which I'll try to
> do later, and I have further powerpc patches that rely on this).
> 
> The current get_unmapped_area code calls the f_ops->get_unmapped_area or
> the arch one (via the mm) only when MAP_FIXED is not passed. That makes
> it impossible for archs to impose proper constraints on regions of the
> virtual address space. To work around that, get_unmapped_area() then
> calls some hugetlbfs specific hacks.
> 
> This cause several problems, among others:
> 
>  - It makes it impossible for a driver or filesystem to do the same thing
> that hugetlbfs does (for example, to allow a driver to use larger page
> sizes to map external hardware) if that requires applying a constraint
> on the addresses (constraining that mapping in certain regions and other
> mappings out of those regions).
> 
>  - Some archs like arm, mips, sparc, sparc64, sh and sh64 already want
> MAP_FIXED to be passed down in order to deal with aliasing issues.
> The code is there to handle it... but is never called.
> 

Is there any support consideration for nommu arch such as blackfin which
is in the -mm tree now?

It is very kind of you to point out some idea about MAP_FIXED for
Blackfin arch, I will do some help for this.

Thanks 
-Bryan
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/