linux-kernel - Re: Fw: [PATCH] ia64: race flushing icache in do_no

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: <1178066187.19466.69.camel@galaxy.corp.google.com>
Date:	Tue, 01 May 2007 17:36:27 -0700
From:	Rohit Seth <rohitseth@...gle.com>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	"'Hugh Dickins'" <hugh@...itas.com>,
	"'Mike Stroyan'" <mike.stroyan@...com>,
	"'Andrew Morton'" <akpm@...ux-foundation.org>,
	"'Luck, Tony'" <tony.luck@...el.com>, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Fw: [PATCH] ia64: race flushing icache in do_no_page path

On Tue, 2007-05-01 at 21:47 +1000, Nick Piggin wrote:
> Rohit Seth wrote:
> >
> > 
> > It is invalidating any entries (containing same physical address) in both I
> > and D caches.  Any dirty lines in D cache are written back to memory before
> > getting invalidated (ofcourse).
> 
> OK. (should it be issuing both fc and fc.i to be robust in case a
> new implementation doesn't flush the dcache with fc.i?)
> 

For the Itanium case specifically, you only want to invalidate a stale
icache line.  Once that is done, next time icache will pick the correct
updated contents.

> 
> >>There are supposedly no icache lines at that point[**]:
> > 
> > 
> > For this bug to trigger there has to be a (stale) entry in icache containing
> > the old contents of a page that just got updated by kernel as explicit
> > copying of data (DMAs are coherent on ia64, meaning if a device were to
> > write to memory then architecture guarnatees that both I and D caches are
> > invalidated).
> 
> So if we have a dirty dcache line for a given physical address,
> it will _always_ be the case that a subsequent icache load will
> find that dirty data?

yes for ia64.

-rohit

-
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/