linux-kernel - Re: [PATCH 07/12] perf, x86: Avoid checkpointed counters causing excessive TSX aborts v3

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: <20130130205847.GG30577@one.firstfloor.org>
Date:	Wed, 30 Jan 2013 21:58:47 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 07/12] perf, x86: Avoid checkpointed counters causing excessive TSX aborts v3

> That's a very low sampling rate, yet I think it would be rejected by your code.

You mean allowed? 

> But if I come in with frequency 0x7fffffff+1, then that's a very high
> frequency, thus
> small period, I would pass the test. So I think you need to reinforce the test
> for freq=1.

I'm aware that there are some configs that can slip through, but there's
no other choice if we still allow guest perf stat. The cutoff is
somewhat arbitary.

It's not a correctness problem, just things can be unexpectedly slower
and you may see unexpected NMI messages.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
--
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/