linux-kernel - Re: [PATCH 10/28] i386: map enough initial memory to create lowmem mappings

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:	Mon, 23 Apr 2007 09:34:47 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Chuck Ebbert <cebbert@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	virtualization@...ts.osdl.org, lkml <linux-kernel@...r.kernel.org>,
	Zachary Amsden <zach@...are.com>,
	Chris Wright <chrisw@...s-sol.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 10/28] i386: map enough initial memory to create lowmem
 mappings

Eric W. Biederman wrote:
> The only way to ensure this will not happen is to do what we do
> on x86_64 and map the new page table page into our address space
> before we write to it.  Assuming the page we allocate is already
> mapped is simply not robust.
>   

So you mean make alloc_bootmem make sure there's a mapping for the
returned page?  That would be simple enough, though it might interact
strangely with the actual construction of the memory mappings (what if
the page alloc_bootmem just allocated for the pagetable is the page
pagetable_init is actually trying to map?).

I'm not sure about the issue with holes.  I assume you mean that just
because head.S maps a chunk of memory, it isn't necessarily available
for allocation because its a hole.  But does alloc_bootmem know to avoid
them anyway?  Has it already parsed e820 at that point?

    J
-
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/