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.zijls...@chello.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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
