linux-kernel - Re: [PATCH] Add a text

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.LRH.2.00.1311300023070.9932@twin.jikos.cz>
Date:	Sat, 30 Nov 2013 00:24:57 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, x86@...nel.org,
	Andi Kleen <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH] Add a text_poke syscall v2

On Fri, 29 Nov 2013, Oleg Nesterov wrote:

> > > Andi, et al. I am going to discuss the things I do not really
> > > understand, probably this can't make any sense, but...
> >
> > I think it's enough to set the dirty bit in the underlying
> > struct page, no need to play games with the PTE.
> 
> Ah, sorry for confusion, I guess you misunderstood.
> 
> I meant, perhaps sys_text_poke() doesn't the in-kernel text_poke
> machinery altogether?
> 
> Can't we invalidate pte (so that any user will stuck in page fault),
> update the page(s), restore the pte and drop the locks?

Do you think this'd be faster than the int3-based aproach?

We have moved from using stop_machine() to int3-based patching exactly 
because it's much more lightweight.

> This way sys_text_poke() won't be x86-specific, and it will be per-mm.

Good point, it'd be really nice to have this as an alternative on archs 
where breakpoint-based patching wouldn't be possible for some reason.

-- 
Jiri Kosina
SUSE Labs
--
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/