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Re: Preemption-safe kprobe-booster(Re: [PATCH]kprobe booster for IA64)
- From: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- To: Keshavamurthy Anil S <anil dot s dot keshavamurthy at intel dot com>
- Cc: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, SystemTAP <systemtap at sources dot redhat dot com>, Yumiko Sugita <yumiko dot sugita dot yf at hitachi dot com>, Satoshi Oshima <soshima at redhat dot com>, Hideo Aoki <haoki at redhat dot com>, Prasanna S Panchamukhi <prasanna at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>
- Date: Sat, 15 Jul 2006 15:19:41 +0900
- Subject: Re: Preemption-safe kprobe-booster(Re: [PATCH]kprobe booster for IA64)
- Organization: Systems Development Lab., Hitachi, Ltd., Japan
- 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> <20060714112627.A15658@unix-os.sc.intel.com>
Hi, Anil
Keshavamurthy Anil S wrote:
> --Comment here please
> /* Booster probe is not support for preemptable kernel */
>> +#ifdef CONFIG_PREEMPT
> ^^^^^^ Should be #ifndef
That's for sure, I fixed it.
>> + 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.
I think the kretprobe booster is not affected by kernel preemption.
Because all codes on the execution path of kretprobe-booster
are the static assembly codes. These codes are never removed.
>
> Thanks,
> Anil
>
>
Thanks,
--
Masami HIRAMATSU
2nd Research Dept.
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com