From: Andy Lutomirski <luto@kernel.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Juergen Gross <jgross@suse.com>,
LKML <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: Sun, 7 Jul 2019 08:11:23 -0700 [thread overview]
Message-ID: <CALCETrUzP4Wb=WNhGvc7k4oX7QQz1JXZ3-O8PQhs39kmZid0nw@mail.gmail.com> (raw)
In-Reply-To: <CALCETrXvTvFBaQB-kEe4cRTCXUyTbWLbcveWsH-kX4j915c_=w@mail.gmail.com>
On Sun, Jul 7, 2019 at 8:10 AM Andy Lutomirski <luto@kernel.org> wrote:
>
> On Thu, Jul 4, 2019 at 1:03 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Despire the current efforts to read CR2 before tracing happens there
> > still exist a number of possible holes:
> >
> > idtentry page_fault do_page_fault has_error_code=1
> > call error_entry
> > TRACE_IRQS_OFF
> > call trace_hardirqs_off*
> > #PF // modifies CR2
> >
> > CALL_enter_from_user_mode
> > __context_tracking_exit()
> > trace_user_exit(0)
> > #PF // modifies CR2
> >
> > call do_page_fault
> > address = read_cr2(); /* whoopsie */
> >
> > And similar for i386.
> >
> > Fix it by pulling the CR2 read into the entry code, before any of that
> > stuff gets a chance to run and ruin things.
>
> Reviewed-by: Andy Lutomirski <luto@kernel.org>
>
> Subject to the discussion as to whether this is the right approach at all.
FWIW, I'm leaning toward suggesting that we apply the trivial tracing
fix and backport *that*. Then, in -tip, we could revert it and apply
this patch instead.
next prev parent reply other threads:[~2019-07-07 15:11 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
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 [this message]
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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