linux-kernel - Re: [git pull] x86 PAT changes

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]

Message-ID: <alpine.LFD.1.10.0804251808590.2813@woody.linux-foundation.org>
Date:	Fri, 25 Apr 2008 18:12:37 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"H. Peter Anvin" <hpa@...or.com>
cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [git pull] x86 PAT changes

On Fri, 25 Apr 2008, H. Peter Anvin wrote:
> 
> The problem is that that can create cached/uncached aliases, which can cause
> some processors to lock up (especially AMD is known to have a lot of errata in
> this area.)

Umm.. I don't think you understand. Right now, NONPROMISC_DEVMEM doesn't 
just disable mmap() on /dev/mem, it disables totally regular reads and 
writes too. That seems pretty damn excessive.

If it was just mmap(), I don't think it would matter much. I don't think 
we traditionally even supported mmap() on real RAM (because the page 
counting would get confused), and that actually got supported only thanks 
to VM changes that made it possible.

But read/write has always been supported, and shouldn't cause any 
cached/uncached aliases!

		Linus
--
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/