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Date: Fri, 27 May 2011 12:57:14 -0300 From: Arnaldo Carvalho de Melo <acme@...hat.com> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com, mingo@...hat.com, eranian@...gle.com, tzanussi@...il.com, penberg@...helsinki.fi, efault@....de, peterz@...radead.org, davej@...hat.com, davem@...emloft.net, fweisbec@...il.com, kees.cook@...onical.com, tglx@...utronix.de, linux-tip-commits@...r.kernel.org Subject: Re: [tip:perf/urgent] perf symbols: Handle /proc/sys/kernel/kptr_restrict Em Fri, May 27, 2011 at 08:46:42AM -0700, Linus Torvalds escreveu: > On Fri, May 27, 2011 at 1:35 AM, Ingo Molnar <mingo@...e.hu> wrote: > > > > I think the biggest problem is that it is yelling at us even when i'm > > root - and root can access all the pointer values just fine: > > Instead of looking at the kptr_restrict file, please just look at the > addresses in the kallsyms file, and if they are all zero, you know > that it's not a usable kallsyms file (and you can pretty much assume > that it's due to kptr_restrict). > > So I think the whole symbol__read_kptr_restrict() thing is just > pointless. Don't do it. I thought about that, ended up using the file not to rely on the values on kallsyms, too much future proofing, I guess. BTW, the problem reported by Ingo above (yelling even for root) is not a bug, he ran 'perf record' as non root with kptr_restrict set and then ran 'perf report' as root. - Arnaldo -- 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/
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