| 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, 06 Jul 2012 20:12:09 +0200 From: Peter Zijlstra <a.p.zijlstra@...llo.nl> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: mingo@...nel.org, hpa@...or.com, eranian@...gle.com, linux-kernel@...r.kernel.org, fweisbec@...il.com, akpm@...ux-foundation.org, tglx@...utronix.de, linux-tip-commits@...r.kernel.org Subject: Re: [tip:perf/core] perf/x86: Fix USER/KERNEL tagging of samples On Fri, 2012-07-06 at 09:29 -0700, Linus Torvalds wrote: > On Thu, Jul 5, 2012 at 11:20 PM, tip-bot for Peter Zijlstra > <a.p.zijlstra@...llo.nl> wrote: > > > > Several perf interrupt handlers (PEBS,IBS,BTS) re-write regs->ip but > > do not update the segment registers. So use an regs->ip based test > > instead of an regs->cs/regs->flags based test. > > Christ, people, YOU CANNOT DO THIS! > > It is never *ever* valid to test the IP to see if you're in kernel > space or user space. People can do various odd segments etc, the IP is > totally meaningless. > > If the perf handlers fake the IP information, they had better fake the > CS/eflags information too. Because it is *wrong* to look at IP. Don't > do it. PEBS, BTS, LBR don't have CS. PEBS does have eflags. If we cannot do this I'm not sure what we can do :/ -- 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