linux-kernel - Re: new text patching for review

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Date:	Fri, 20 Jul 2007 10:23:40 +0200
From:	Andi Kleen <ak@...e.de>
To:	Zachary Amsden <zach@...are.com>
Cc:	mathieu.desnoyers@...ymtl.ca, jbeulich@...ell.com,
	"S. P. Prasanna" <prasanna@...ibm.com>,
	linux-kernel@...r.kernel.org, patches@...-64.org
Subject: Re: new text patching for review

On Friday 20 July 2007 02:37:20 Zachary Amsden wrote:
> Andi Kleen wrote:
> > +	*addr = opcode;
> > +	/* Not strictly needed, but can speed CPU recovery up */
> > +	if (cpu_has_clflush)
> > +		asm("clflush (%0) " :: "r" (addr) : "memory");
> > +	if (addr != oaddr)
> > +		vunmap(addr);
> >   
> 
> clflush should take oaddr.

Thanks

> If you had to remap, note that the processor does not know the linear 
> address you wrote to could be matched by another mapping in icache.  In 
> that case, you'll need a serializing instruction (cpuid) to 
> resynchronize caches.

We already got one in alternative patching, but you're right it's 
safer to do it in text_poke

-Andi
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