From: "H. Peter Anvin" <hpa@zytor.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Dave Jones <davej@redhat.com>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 4/5] x86: Allow nesting of the debug stack IDT setting
Date: Thu, 31 May 2012 12:27:40 -0700 [thread overview]
Message-ID: <4FC7C62C.1020807@zytor.com> (raw)
In-Reply-To: <1338492300.13348.384.camel@gandalf.stny.rr.com>
On 05/31/2012 12:25 PM, Steven Rostedt wrote:
>> void debug_stack_set_zero(void)
>> {
>> if (this_cpu_inc_return(debug_stack_use_ctr) == 1)
>
> If an NMI comes in here, it will not update the IDT and will corrupt the
> stack. The load_idt() must happen for all calls. There's only two static
> IDT tables. It's either one or the other. Thus, if it loads it twice, it
> will just set it to the same value. The counter is to know when to set
> it back.
>
Now I'm really confused. Why would it have to set it if it is already set?
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-05-31 19:28 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-31 1:28 [PATCH 0/5] [GIT PULL] ftrace: Fix bug with function tracing and lockdep Steven Rostedt
2012-05-31 1:28 ` [PATCH 1/5] ftrace: Synchronize variable setting with breakpoints Steven Rostedt
2012-05-31 11:06 ` Peter Zijlstra
2012-05-31 14:08 ` Steven Rostedt
2012-05-31 15:16 ` Masami Hiramatsu
2012-05-31 15:29 ` Steven Rostedt
2012-05-31 17:28 ` Peter Zijlstra
2012-05-31 18:42 ` Steven Rostedt
2012-05-31 17:40 ` Peter Zijlstra
2012-05-31 17:44 ` Peter Zijlstra
2012-05-31 17:53 ` Steven Rostedt
2012-05-31 18:03 ` Peter Zijlstra
2012-05-31 18:50 ` Steven Rostedt
2012-05-31 19:06 ` Peter Zijlstra
2012-05-31 19:55 ` Mathieu Desnoyers
2012-05-31 20:10 ` Steven Rostedt
2012-05-31 20:26 ` Peter Zijlstra
2012-05-31 20:37 ` Steven Rostedt
2012-05-31 20:40 ` Steven Rostedt
2012-05-31 20:40 ` Peter Zijlstra
2012-05-31 20:49 ` Steven Rostedt
2012-06-01 4:53 ` Masami Hiramatsu
2012-06-01 11:37 ` Steven Rostedt
2012-06-01 12:52 ` Masami Hiramatsu
2012-06-01 0:45 ` Arnaldo Carvalho de Melo
2012-05-31 1:28 ` [PATCH 2/5] ftrace: Use breakpoint method to update ftrace caller Steven Rostedt
2012-05-31 11:18 ` Peter Zijlstra
2012-05-31 14:19 ` Steven Rostedt
2012-05-31 1:28 ` [PATCH 3/5] x86: Reset the debug_stack update counter Steven Rostedt
2012-05-31 19:19 ` H. Peter Anvin
2012-05-31 19:26 ` Steven Rostedt
2012-05-31 1:28 ` [PATCH 4/5] x86: Allow nesting of the debug stack IDT setting Steven Rostedt
2012-05-31 18:44 ` H. Peter Anvin
2012-05-31 18:58 ` H. Peter Anvin
2012-05-31 19:25 ` Steven Rostedt
2012-05-31 19:27 ` H. Peter Anvin [this message]
2012-05-31 20:00 ` Steven Rostedt
2012-05-31 20:17 ` H. Peter Anvin
2012-05-31 20:35 ` Steven Rostedt
2012-05-31 20:39 ` H. Peter Anvin
2012-05-31 20:56 ` Steven Rostedt
2012-05-31 21:09 ` H. Peter Anvin
2012-05-31 21:37 ` Steven Rostedt
2012-05-31 21:38 ` Steven Rostedt
2012-06-01 2:30 ` Steven Rostedt
2012-05-31 1:28 ` [PATCH 5/5] ftrace/x86: Do not change stacks in DEBUG when calling lockdep Steven Rostedt
2012-05-31 2:13 ` [PATCH 0/5] (for 3.5)[GIT PULL] ftrace: Fix bug with function tracing and lockdep Steven Rostedt
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