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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Andrew Lutomirski <luto@kernel.org>, Peter Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Juergen Gross <jgross@suse.com>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	He Zhe <zhe.he@windriver.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	devel@etsukata.com
Subject: Re: [PATCH v2 5/7] x86/mm, tracing: Fix CR2 corruption
Date: Fri, 5 Jul 2019 11:18:51 +0900	[thread overview]
Message-ID: <CAHk-=wiJ4no+TW-8KTfpO-Q5+aaTGVoBJzrnFTvj_zGpVbrGfA@mail.gmail.com> (raw)
In-Reply-To: <20190704200050.534802824@infradead.org>

On Fri, Jul 5, 2019 at 5:03 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> Despire the current efforts to read CR2 before tracing happens there
> still exist a number of possible holes:

So this whole series disturbs me for the simple reason that I thought
tracing was supposed to save/restore cr2 and make it unnecessary to
worry about this in non-tracing code.

That is very much what the NMI code explicitly does. Why shouldn't all
the other tracing code do the same thing in case they can take page
faults?

So I don't think the patches are wrong per se, but this seems to solve
it at the wrong level.

                 Linus

  reply	other threads:[~2019-07-05  2:19 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-04 19:55 [PATCH v2 0/7] Tracing vs CR2 (and cleanups) Peter Zijlstra
2019-07-04 19:55 ` [PATCH v2 1/7] x86/paravirt: Make read_cr2() CALLEE_SAVE Peter Zijlstra
2019-07-04 21:49   ` Andy Lutomirski
2019-07-10 19:53   ` Steven Rostedt
2019-07-04 19:55 ` [PATCH v2 2/7] x86/entry/32: Simplify common_exception Peter Zijlstra
2019-07-04 21:51   ` Andy Lutomirski
2019-07-10 20:11   ` Steven Rostedt
2019-07-10 20:14     ` Peter Zijlstra
2019-07-04 19:55 ` [PATCH v2 3/7] x86/entry/64: Simplify idtentry a little Peter Zijlstra
2019-07-04 21:54   ` Andy Lutomirski
2019-07-10 20:23   ` Steven Rostedt
2019-07-04 19:55 ` [PATCH v2 4/7] x86/entry/64: Update comments and sanity tests for create_gap Peter Zijlstra
2019-07-04 21:55   ` Andy Lutomirski
2019-07-10 20:24   ` Steven Rostedt
2019-07-04 19:56 ` [PATCH v2 5/7] x86/mm, tracing: Fix CR2 corruption Peter Zijlstra
2019-07-05  2:18   ` Linus Torvalds [this message]
2019-07-05  3:16     ` Andy Lutomirski
2019-07-05  3:27       ` Linus Torvalds
2019-07-05 13:49     ` Peter Zijlstra
2019-07-06 21:41       ` Linus Torvalds
2019-07-06 22:27         ` Steven Rostedt
2019-07-06 22:41           ` Linus Torvalds
2019-07-07  0:08             ` Linus Torvalds
2019-07-07  0:36               ` Andy Lutomirski
2019-07-06 23:50           ` Andy Lutomirski
2019-07-07  3:44           ` Eiichi Tsukata
2019-07-06 11:07     ` Eiichi Tsukata
2019-07-08  7:48       ` Peter Zijlstra
2019-07-08  8:58         ` Eiichi Tsukata
2019-07-08  9:42           ` Eiichi Tsukata
2019-07-09  5:17             ` Eiichi Tsukata
2019-07-07 15:10   ` Andy Lutomirski
2019-07-07 15:11     ` Andy Lutomirski
2019-07-07 18:17       ` Linus Torvalds
2019-07-10 20:27         ` Steven Rostedt
2019-07-11  6:45           ` Greg Kroah-Hartman
2019-07-11 12:12           ` Sasha Levin
2019-07-11 12:21           ` Peter Zijlstra
2019-07-04 19:56 ` [PATCH v2 6/7] x86/entry/64: Remove TRACE_IRQS_*_DEBUG Peter Zijlstra
2019-07-11  3:24   ` Steven Rostedt
2019-07-11  8:05     ` Peter Zijlstra
2019-07-04 19:56 ` [RFC][PATCH v2 7/7] x86/entry/64: Pull bits into C Peter Zijlstra

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