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Date: Fri, 14 Jul 2006 18:41:00 -0000
From: Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com>,    Ananth N Mavinakayanahalli <ananth@in.ibm.com>,    SystemTAP <systemtap@sources.redhat.com>,    Yumiko Sugita <yumiko.sugita.yf@hitachi.com>,    Satoshi Oshima <soshima@redhat.com>, Hideo Aoki <haoki@redhat.com>,    Prasanna S Panchamukhi <prasanna@in.ibm.com>,    Jim Keniston <jkenisto@us.ibm.com>
Subject: Re: Preemption-safe kprobe-booster(Re: [PATCH]kprobe booster for IA64)
Message-ID: <20060714112627.A15658@unix-os.sc.intel.com>
Reply-To: Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com>
References: <4485223C.8090109@sdl.hitachi.co.jp> <20060628190541.A13874@unix-os.sc.intel.com> <44AAF207.7090908@sdl.hitachi.co.jp> <44B4952D.9010603@hitachi.com> <20060712010122.A30357@unix-os.sc.intel.com> <44B62D9D.20303@hitachi.com>
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In-Reply-To: <44B62D9D.20303@hitachi.com>; from masami.hiramatsu.pt@hitachi.com on Thu, Jul 13, 2006 at 08:25:17PM +0900
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On Thu, Jul 13, 2006 at 08:25:17PM +0900, Masami Hiramatsu wrote:
> Hi, Anil
> Thank you for precise advice.
> 
> Keshavamurthy Anil S wrote:
> > On Wed, Jul 12, 2006 at 03:22:37PM +0900, Masami Hiramatsu wrote:
> Now, we are searching for other good solutions against this problem.
> 
> Anyway, I'd like to disable booster when CONFIG_PREEMPT is defined
> until this problem is solved. I attached the patch to this mail.
> Please review it.
> 

--Comment here please 
 /* Booster probe is not support for preemptable kernel */
> +#ifdef CONFIG_PREEMPT
   ^^^^^^ Should be #ifndef
> +	if (p->ainsn.boostable == 1 && !p->post_handler){
>  		/* Boost up -- we can execute copied instructions directly */
>  		reset_current_kprobe();
>  		regs->eip = (unsigned long)p->ainsn.insn;
>  		preempt_enable_no_resched();
>  		return 1;
>  	}
> +#endif
>  	prepare_singlestep(p, regs);
>  	kcb->kprobe_status = KPROBE_HIT_SS;
>  	return 1;

Also you may want to do the same thing for kretprobe booster.

Thanks,
Anil