From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <JGross@suse.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check()
Date: Wed, 26 Feb 2020 19:42:37 +0100 [thread overview]
Message-ID: <20200226184237.GB16756@zn.tnic> (raw)
In-Reply-To: <C06C32B4-BD69-4287-BC67-C3E225061A46@amacapital.net>
On Wed, Feb 26, 2020 at 09:28:51AM -0800, Andy Lutomirski wrote:
> > It entirely depends on what the goal is :-/ On the one hand I see why
> > people might want function tracing / kprobes enabled, OTOH it's all
> > mighty frigging scary. Any tracing/probing/whatever on an MCE has the
> > potential to make a bad situation worse -- not unlike the same on #DF.
FWIW, I had this at the beginning of the #MC handler in a feeble attempt
to poke at this:
+ hw_breakpoint_disable();
+ static_key_disable(&__tracepoint_read_msr.key);
+ tracing_off();
But then Tony noted that some recoverable errors do get reported with an
#MC exception so we would have to look at the error severity and then
decide whether to allow tracing or not.
But the error severity happens all the way down in __mc_scan_banks() -
i.e., we've executed the half handler already.
So, frankly, I wanna say, f*ck tracing etc - there are certain handlers
which simply don't allow it. And we'll only consider changing that when
a really good reason for it appears...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-02-26 18:42 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-25 21:36 [patch 00/10] x86/entry: Consolidation - Part I Thomas Gleixner
2020-02-25 21:36 ` [patch 01/10] x86/entry/32: Add missing ASM_CLAC to general_protection entry Thomas Gleixner
2020-02-26 1:00 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() Thomas Gleixner
2020-02-26 1:13 ` Frederic Weisbecker
2020-02-26 5:29 ` Andy Lutomirski
2020-02-26 13:28 ` Peter Zijlstra
2020-02-26 15:10 ` Andy Lutomirski
2020-02-26 16:08 ` Peter Zijlstra
2020-02-26 17:28 ` Andy Lutomirski
2020-02-26 18:42 ` Borislav Petkov [this message]
2020-02-26 18:59 ` Peter Zijlstra
2020-02-26 19:09 ` Andy Lutomirski
2020-02-26 20:59 ` Steven Rostedt
2020-02-26 11:18 ` Borislav Petkov
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-02-25 21:36 ` [patch 03/10] x86/entry/32: Force MCE through do_mce() Thomas Gleixner
2020-02-26 1:11 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 04/10] x86/traps: Remove pointless irq enable from do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 1:19 ` Frederic Weisbecker
2020-02-25 21:36 ` [patch 05/10] x86/traps: Document do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 17:08 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 06/10] x86/traps: Remove redundant declaration of do_double_fault() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 07/10] x86/irq: Remove useless return value from do_IRQ() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 08/10] x86/entry/32: Remove the 0/-1 distinction from exception entries Thomas Gleixner
2020-02-26 5:34 ` Andy Lutomirski
2020-02-26 18:42 ` Thomas Gleixner
2020-02-26 18:57 ` Andy Lutomirski
2020-02-26 19:15 ` Thomas Gleixner
2020-02-27 14:24 ` [patch V2 " Thomas Gleixner
2020-02-29 11:49 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 09/10] x86/entry/entry_32: Route int3 through common_exception Thomas Gleixner
2020-02-26 17:35 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 10/10] x86/traps: Stop using ist_enter/exit() in do_int3() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-27 14:33 ` tip-bot2 for Andy Lutomirski
2020-02-26 5:26 ` [patch 00/10] x86/entry: Consolidation - Part I Andy Lutomirski
2020-02-26 5:35 ` Andy Lutomirski
2020-02-27 11:01 ` Alexandre Chartre
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