linux-kernel - Re: [RFC PATCH 2/8] jump label v4 - x86: Introduce generic jump patching without stop

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Message-ID: <4B4F3A1A.2030906@zytor.com>
Date:	Thu, 14 Jan 2010 07:36:58 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	rostedt@...dmis.org
CC:	Jason Baron <jbaron@...hat.com>, linux-kernel@...r.kernel.org,
	mingo@...e.hu, mathieu.desnoyers@...ymtl.ca, tglx@...utronix.de,
	andi@...stfloor.org, roland@...hat.com, rth@...hat.com,
	mhiramat@...hat.com, Arjan van de Ven <arjan@...radead.org>
Subject: Re: [RFC PATCH 2/8] jump label v4 - x86: Introduce generic jump patching
 without stop_machine

On 01/14/2010 07:32 AM, Steven Rostedt wrote:
>> +
>> +	/* Replacing 1 byte can be done atomically. */
>> +	if (unlikely(len <= 1))
>> +		return text_poke(addr, opcode, len);
> 
> This part bothers me. The text_poke just writes over the text directly
> (using a separate mapping). But if that memory is in the pipeline of
> another CPU, I think this could cause a GPF.
> 

Could you clarify why you think that?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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