| 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
| ||
|
Date: Fri, 29 Aug 2008 18:37:49 +0200 From: Andi Kleen <andi@...stfloor.org> To: Gregory Haskins <ghaskins@...ell.com> Cc: Andi Kleen <andi@...stfloor.org>, Gregory Haskins <gregory.haskins@...il.com>, mingo@...e.hu, rostedt@...dmis.org, tglx@...utronix.de, linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org Subject: Re: [PATCH] seqlock: serialize against writers On Fri, Aug 29, 2008 at 12:29:42PM -0400, Gregory Haskins wrote: > Andi Kleen wrote: > >> Im running it on a x86_64 box as we speak. How can I tell if there is a > >> certain mode that is permitting this? > >> > > > > If the boot up says you're running with PMtimer then it uses the fallback > > (usually happens on pre Fam10h AMD boxes). A typical Intel box > > would use the faster ring 3 only TSC path and then explode with your > > change I bet. > > > > Thinking about this some more, perhaps the issue is I am not hitting the > contended path in vsyscall? Yes it will be only contended when gettimeofday() races with the timer interrupt. You could try to run gettimeofday() in a loop and see how long it holds up. But anyways from the theory you should crash when it happens. Writes to kernel data are not allowed in vsyscalls and your read_lock clearly does a write. -Andi -- ak@...ux.intel.com -- 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/
Powered by blists - more mailing lists