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From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	rostedt@goodmis.org, james.morse@arm.com,
	catalin.marinas@arm.com, mingo@kernel.org,
	joel@joelfernandes.org, gregkh@linuxfoundation.org,
	gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org,
	josh@joshtriplett.org, mathieu.desnoyers@efficios.com,
	jiangshanlai@gmail.com
Subject: Re: [PATCH 0/8] tracing vs rcu vs nmi
Date: Wed, 12 Feb 2020 12:58:20 +0100	[thread overview]
Message-ID: <20200212115820.GQ14897@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200212105646.GA4017@willie-the-truck>

On Wed, Feb 12, 2020 at 10:56:46AM +0000, Will Deacon wrote:
> On Wed, Feb 12, 2020 at 11:01:06AM +0100, Peter Zijlstra wrote:
> > On Wed, Feb 12, 2020 at 10:32:10AM +0100, Peter Zijlstra wrote:
> > > Hi all,
> > > 
> > > These here patches are the result of Mathieu and Steve trying to get commit
> > > 865e63b04e9b2 ("tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle
> > > tracepoints") reverted again.
> > > 
> > > One of the things discovered is that tracing MUST NOT happen before nmi_enter()
> > > or after nmi_exit(). I've only fixed x86, but quickly gone through other
> > > architectures and there is definitely more stuff to be fixed (simply grep for
> > > nmi_enter in your arch).
> > 
> > For ARM64:
> > 
> >  - apei_claim_sea()
> >  - __sdei_handler()
> >  - do_serror()
> >  - debug_exception_enter() / do_debug_exception()
> > 
> > all look dodgy.
> 
> Hmm, so looks like we need to spinkle some 'notrace' annotations around
> these. Are there are scenarios where you would want NOKPROBE_SYMBOL() but
> *not* 'notrace'? We've already got the former for the debug exception
> handlers and we probably (?) want it for the SDEI stuff too...

I'm not sure. In fact, I asked Steve on IRC if we'd want to teach
objtool to report such inconsitencies.

  reply	other threads:[~2020-02-12 11:59 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12  9:32 [PATCH 0/8] tracing vs rcu vs nmi Peter Zijlstra
2020-02-12  9:32 ` [PATCH 1/8] rcu: Rename rcu_irq_{enter,exit}_irqson() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 2/8] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline Peter Zijlstra
2020-02-12  9:32 ` [PATCH 3/8] rcu,tracing: Create trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 4/8] sched,rcu,tracing: Mark preempt_count_{add,sub}() notrace Peter Zijlstra
2020-02-12 14:24   ` Steven Rostedt
2020-02-12 15:02     ` Peter Zijlstra
2020-02-12 15:14       ` Steven Rostedt
2020-02-12 15:38         ` Peter Zijlstra
2020-02-12  9:32 ` [PATCH 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)() notrace Peter Zijlstra
2020-02-12 14:25   ` Steven Rostedt
2020-02-12 15:04     ` Peter Zijlstra
2020-02-12 15:18       ` Steven Rostedt
2020-02-12 15:39         ` Peter Zijlstra
2020-02-12  9:32 ` [PATCH 6/8] perf,tracing: Prepare the perf-trace interface for RCU changes Peter Zijlstra
2020-02-12 14:26   ` Steven Rostedt
2020-02-12 15:07     ` Mathieu Desnoyers
2020-02-12  9:32 ` [PATCH 7/8] tracing: Employ trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 8/8] tracing: Remove regular RCU context for _rcuidle tracepoints (again) Peter Zijlstra
2020-02-12 14:29   ` Steven Rostedt
2020-02-12 15:12     ` Peter Zijlstra
2020-02-12 10:01 ` [PATCH 0/8] tracing vs rcu vs nmi Peter Zijlstra
2020-02-12 10:56   ` Will Deacon
2020-02-12 11:58     ` Peter Zijlstra [this message]
2020-02-12 14:32     ` Steven Rostedt
2020-02-12 15:21       ` Peter Zijlstra
2020-02-12 10:03 ` Peter Zijlstra
2020-02-12 10:07 ` Peter Zijlstra
2020-02-12 10:09 ` Peter Zijlstra

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