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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
	paulmck <paulmck@kernel.org>, Andy Lutomirski <luto@kernel.org>,
	Alexandre Chartre <alexandre.chartre@oracle.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Petr Mladek <pmladek@suse.com>, rostedt <rostedt@goodmis.org>,
	"Joel Fernandes, Google" <joel@joelfernandes.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>, Brian Gerst <brgerst@gmail.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch V4 part 1 35/36] x86: Replace ist_enter() with nmi_enter()
Date: Wed, 13 May 2020 20:12:36 -0400 (EDT)	[thread overview]
Message-ID: <1443118821.20546.1589415156226.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20200505134101.525508608@linutronix.de>

----- On May 5, 2020, at 9:16 AM, Thomas Gleixner tglx@linutronix.de wrote:

> From: Peter Zijlstra <peterz@infradead.org>
> 
> A few exceptions (like #DB and #BP) can happen at any location in the code,
> this then means that tracers should treat events from these exceptions as
> NMI-like. The interrupted context could be holding locks with interrupts
> disabled for instance.
> 
> Similarly, #MC is an actual NMI-like exception.
> 
> All of them use ist_enter() which only concerns itself with RCU, but does
> not do any of the other setup that NMIs need. This means things like:
> 
>	printk()
>	  raw_spin_lock_irq(&logbuf_lock);
>	  <#DB/#BP/#MC>
>	     printk()
>	       raw_spin_lock_irq(&logbuf_lock);
> 
> are entirely possible (well, not really since printk tries hard to
> play nice, but the concept stands).
> 
> So replace ist_enter() with nmi_enter(). Also observe that any nmi_enter()
> caller must be both notrace and NOKPROBE, or in the noinstr text section.

Are there similar issues with non-x86 architectures, or is this
exception-behaves-like-an-interrupt issue specific to x86 ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

  parent reply	other threads:[~2020-05-14  0:12 UTC|newest]

Thread overview: 178+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05 13:16 [patch V4 part 1 00/36] x86/entry: Entry/exception code rework, preparatory patches Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 01/36] rcu: Add comments marking transitions between RCU watching and not Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 02/36] x86/hw_breakpoint: Prevent data breakpoints on cpu_entry_area Thomas Gleixner
2020-05-06  8:14   ` Borislav Petkov
2020-05-06 12:11   ` Alexandre Chartre
2020-05-09  9:00   ` Lai Jiangshan
2020-05-09  9:23   ` Lai Jiangshan
2020-05-09 19:08     ` Andy Lutomirski
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-05-05 13:16 ` [patch V4 part 1 03/36] sched: Clean up scheduler_ipi() Thomas Gleixner
2020-05-06  8:32   ` Thomas Gleixner
2020-05-06  8:40   ` Borislav Petkov
2020-05-06  9:12     ` Thomas Gleixner
2020-05-06 10:02       ` Borislav Petkov
2020-05-06 12:37   ` Alexandre Chartre
2020-05-06 15:03     ` Thomas Gleixner
2020-05-06 15:33     ` Peter Zijlstra
2020-05-06 18:28       ` Paul E. McKenney
2020-05-06 18:37         ` Peter Zijlstra
2020-05-06 18:46           ` Paul E. McKenney
2020-05-12 15:13   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra (Intel)
2020-05-05 13:16 ` [patch V4 part 1 04/36] sched: Make scheduler_ipi inline Thomas Gleixner
2020-05-06 12:42   ` Alexandre Chartre
2020-05-12 15:13   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 05/36] x86/entry: Flip _TIF_SIGPENDING and _TIF_NOTIFY_RESUME handling Thomas Gleixner
2020-05-06 11:53   ` Miroslav Benes
2020-05-06 12:06     ` Thomas Gleixner
2020-05-06 15:35     ` Peter Zijlstra
2020-05-06 13:06   ` Alexandre Chartre
2020-05-06 16:26   ` Borislav Petkov
2020-05-07 17:35   ` Andy Lutomirski
2020-05-13 20:56   ` Mathieu Desnoyers
2020-05-13 21:10     ` Steven Rostedt
2020-05-13 22:48       ` Mathieu Desnoyers
2020-05-14  0:12       ` Thomas Gleixner
2020-05-14  0:37         ` Steven Rostedt
2020-05-14  0:49           ` Thomas Gleixner
2020-05-14  1:22         ` Andy Lutomirski
2020-05-14  2:51         ` Mathieu Desnoyers
2020-05-14  9:19           ` Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 06/36] compiler: Simple READ/WRITE_ONCE() implementations Thomas Gleixner
2020-05-06 13:11   ` Alexandre Chartre
2020-05-06 13:33   ` Will Deacon
2020-05-06 15:36     ` Peter Zijlstra
2020-05-06 16:33   ` Borislav Petkov
2020-05-05 13:16 ` [patch V4 part 1 07/36] locking/atomics: Flip fallbacks and instrumentation Thomas Gleixner
2020-05-05 16:04   ` Mark Rutland
2020-05-07 23:41   ` Steven Rostedt
2020-05-08  8:40     ` Peter Zijlstra
2020-05-12 14:36   ` [tip: locking/kcsan] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 08/36] x86/doublefault: Remove memmove() call Thomas Gleixner
2020-05-06 13:47   ` Alexandre Chartre
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 09/36] x86/entry/64: Avoid pointless code when CONTEXT_TRACKING=n Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 10/36] x86/entry: Remove the unused LOCKDEP_SYSEXIT cruft Thomas Gleixner
2020-05-06 13:52   ` Alexandre Chartre
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 11/36] x86/kvm: Handle async page faults directly through do_page_fault() Thomas Gleixner
2020-05-06  7:00   ` Paolo Bonzini
2020-05-06 14:05   ` Alexandre Chartre
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-05-05 13:16 ` [patch V4 part 1 12/36] x86/kvm: Sanitize kvm_async_pf_task_wait() Thomas Gleixner
2020-05-05 17:54   ` Paul E. McKenney
2020-05-05 21:50     ` Thomas Gleixner
2020-05-06  7:00   ` Paolo Bonzini
2020-05-06 12:53     ` Steven Rostedt
2020-05-06 15:13   ` Alexandre Chartre
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 13/36] x86/kvm: Restrict ASYNC_PF to user space Thomas Gleixner
2020-05-06  7:00   ` Paolo Bonzini
2020-05-06 15:29   ` Alexandre Chartre
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 14/36] x86/entry: Get rid of ist_begin/end_non_atomic() Thomas Gleixner
2020-05-06 15:34   ` Alexandre Chartre
2020-05-07 17:46   ` Andy Lutomirski
2020-05-13 22:57   ` Mathieu Desnoyers
2020-05-14  0:13     ` Steven Rostedt
2020-05-15  9:34     ` Thomas Gleixner
2020-05-15 13:11       ` Mathieu Desnoyers
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 15/36] kprobes: Lock kprobe_mutex while showing kprobe_blacklist Thomas Gleixner
2020-05-06 15:38   ` Alexandre Chartre
2020-05-12 15:18   ` [tip: core/kprobes] " tip-bot2 for Masami Hiramatsu
2020-05-05 13:16 ` [patch V4 part 1 16/36] kprobes: Support __kprobes blacklist in modules Thomas Gleixner
2020-05-06 15:47   ` Alexandre Chartre
2020-05-12 15:18   ` [tip: core/kprobes] " tip-bot2 for Masami Hiramatsu
2020-05-05 13:16 ` [patch V4 part 1 17/36] kprobes: Support NOKPROBE_SYMBOL() " Thomas Gleixner
2020-05-06 15:54   ` Alexandre Chartre
2020-05-12 15:18   ` [tip: core/kprobes] " tip-bot2 for Masami Hiramatsu
2020-05-05 13:16 ` [patch V4 part 1 18/36] samples/kprobes: Add __kprobes and NOKPROBE_SYMBOL() for handlers Thomas Gleixner
2020-05-06 15:57   ` Alexandre Chartre
2020-05-12 15:18   ` [tip: core/kprobes] " tip-bot2 for Masami Hiramatsu
2020-05-05 13:16 ` [patch V4 part 1 19/36] x86/entry: Exclude low level entry code from sanitizing Thomas Gleixner
2020-05-05 20:39   ` Brian Gerst
2020-05-06 15:42     ` Peter Zijlstra
2020-05-06 16:03   ` Alexandre Chartre
2020-05-13 22:58     ` Mathieu Desnoyers
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 20/36] vmlinux.lds.h: Create section for protection against instrumentation Thomas Gleixner
2020-05-06 16:08   ` Sean Christopherson
2020-05-06 16:28     ` Peter Zijlstra
2020-05-06 16:57       ` Thomas Gleixner
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 21/36] kprobes: Prevent probes in .noinstr.text section Thomas Gleixner
2020-05-08  6:30   ` Masami Hiramatsu
2020-05-19 19:52   ` [tip: core/kprobes] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 22/36] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-05-07 17:55   ` Andy Lutomirski
2020-05-07 18:52     ` Thomas Gleixner
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 23/36] bug: Annotate WARN/BUG/stackfail as noinstr safe Thomas Gleixner
2020-05-13 23:12   ` Mathieu Desnoyers
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-05-05 13:16 ` [patch V4 part 1 24/36] lockdep: Prepare for noinstr sections Thomas Gleixner
2020-05-08  0:23   ` Steven Rostedt
2020-05-08  8:44     ` Peter Zijlstra
2020-05-19 19:58   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 25/36] rcu/tree: Mark the idle relevant functions noinstr Thomas Gleixner
2020-05-05 18:07   ` Paul E. McKenney
2020-05-19 19:48   ` Joel Fernandes
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Thomas Gleixner
2020-09-28 22:22     ` Kim Phillips
2020-09-28 22:55       ` Paul E. McKenney
2020-09-29  7:25       ` Peter Zijlstra
2020-09-29 11:25     ` Peter Zijlstra
2020-09-29 14:34       ` Steven Rostedt
2020-09-29 14:52         ` Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 26/36] printk: Prepare for nested printk_nmi_enter() Thomas Gleixner
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Petr Mladek
2020-05-05 13:16 ` [patch V4 part 1 27/36] arm64: Prepare arch_nmi_enter() for recursion Thomas Gleixner
2020-05-13 23:28   ` Mathieu Desnoyers
2020-05-15 14:04     ` Frederic Weisbecker
2020-05-15 15:45       ` Will Deacon
2020-05-15 16:01         ` Mathieu Desnoyers
2020-05-15 21:29   ` Thomas Gleixner
2020-05-15 21:31     ` Frederic Weisbecker
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Frederic Weisbecker
2020-05-05 13:16 ` [patch V4 part 1 28/36] hardirq/nmi: Allow nested nmi_enter() Thomas Gleixner
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work Thomas Gleixner
2020-05-07 18:02   ` Andy Lutomirski
2020-05-08  8:48     ` Peter Zijlstra
2020-05-08 21:30       ` Andy Lutomirski
2020-05-14 14:16     ` Borislav Petkov
2020-05-13 23:42   ` Mathieu Desnoyers
2020-05-14 17:38     ` Thomas Gleixner
2020-05-14 17:42       ` Mathieu Desnoyers
2020-05-14 14:17   ` Borislav Petkov
2020-05-14 16:03     ` Mathieu Desnoyers
2020-05-14 16:19       ` Andy Lutomirski
2020-05-14 16:39       ` Borislav Petkov
2020-05-14 17:05         ` Mathieu Desnoyers
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 30/36] lockdep: Always inline lockdep_{off,on}() Thomas Gleixner
2020-05-13 23:46   ` Mathieu Desnoyers
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 31/36] printk: Disallow instrumenting print_nmi_enter() Thomas Gleixner
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 32/36] sh/ftrace: Move arch_ftrace_nmi_{enter,exit} into nmi exception Thomas Gleixner
2020-05-08  0:34   ` Steven Rostedt
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 33/36] x86,tracing: Robustify ftrace_nmi_enter() Thomas Gleixner
2020-05-08  6:19   ` Masami Hiramatsu
2020-05-05 13:16 ` [patch V4 part 1 34/36] sched,rcu,tracing: Avoid tracing before in_nmi() is correct Thomas Gleixner
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 35/36] x86: Replace ist_enter() with nmi_enter() Thomas Gleixner
2020-05-07 18:04   ` Andy Lutomirski
2020-05-07 18:17     ` Mathieu Desnoyers
2020-05-08  8:50       ` Peter Zijlstra
2020-05-08 17:12         ` Josh Poimboeuf
2020-05-14  0:12   ` Mathieu Desnoyers [this message]
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Peter Zijlstra
2020-05-05 13:16 ` [patch V4 part 1 36/36] rcu: Make RCU IRQ enter/exit functions rely on in_nmi() Thomas Gleixner
2020-05-05 18:13   ` Paul E. McKenney
2020-05-06 17:09   ` Alexandre Chartre
2020-05-19 19:52   ` [tip: core/rcu] " tip-bot2 for Paul E. McKenney
2020-05-07 18:05 ` [patch V4 part 1 00/36] x86/entry: Entry/exception code rework, preparatory patches Andy Lutomirski

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