Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754962AbaBEBVt (ORCPT ); Tue, 4 Feb 2014 20:21:49 -0500 Received: from mail9.hitachi.co.jp ([133.145.228.44]:38759 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751732AbaBEBVs (ORCPT ); Tue, 4 Feb 2014 20:21:48 -0500 Message-ID: <52F19223.5010506@hitachi.com> Date: Wed, 05 Feb 2014 10:21:39 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Chen Gang Cc: ananth@in.ibm.com, anil.s.keshavamurthy@intel.com, =?UTF-8?B?SMOldmFy?= =?UTF-8?B?ZCBTa2lubmVtb2Vu?= , David Miller , "linux-kernel@vger.kernel.org" , Hans-Christian Egtvedt , "yrl.pp-manager.tt@hitachi.com" , Ingo Molnar Subject: Re: [PATCH] kernel: kprobe: move all *kretprobe* generic implementation to CONFIG_KRETPROBES enabled area References: <52ECE5D8.6090209@gmail.com> <52EDB022.5070101@hitachi.com> <52EF8222.6030709@gmail.com> <52EFB8F4.6010207@hitachi.com> <52F04FA8.8040008@gmail.com> <52F077A1.3020701@gmail.com> <52F09404.3060502@hitachi.com> <52F0D7F3.7000901@gmail.com> <52F0EB30.2070401@hitachi.com> <52F0F0ED.5090005@gmail.com> <52F109AF.8040800@hitachi.com> <52F18367.2060803@gmail.com> In-Reply-To: <52F18367.2060803@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/02/05 9:18), Chen Gang wrote: > On 02/04/2014 11:39 PM, Masami Hiramatsu wrote: >> (2014/02/04 22:53), Chen Gang wrote: >>> On 02/04/2014 09:29 PM, Masami Hiramatsu wrote: >>>> (2014/02/04 21:07), Chen Gang wrote: >>>>> On 02/04/2014 03:17 PM, Masami Hiramatsu wrote: >>>>>> (2014/02/04 14:16), Chen Gang wrote: >>>>>>> When CONFIG_KRETPROBES disabled, all *kretprobe* generic implementation >>>>>>> are useless, so need move them to CONFIG_KPROBES enabled area. >>>>>>> >>>>>>> Now, *kretprobe* generic implementation are all implemented in 2 files: >>>>>>> >>>>>>> - in "include/linux/kprobes.h": >>>>>>> >>>>>>> move inline kretprobe*() to CONFIG_KPROBES area and dummy outside. >>>>>>> move some *kprobe() declarations which kretprobe*() call, to front. >>>>>>> not touch kretprobe_blacklist[] which is architecture's variable. >>>>>>> >>>>>>> - in "kernel/kprobes.c": >>>>>>> >>>>>>> move all kretprobe* to CONFIG_KPROBES area and dummy outside. >>>>>>> define kretprobe_flush_task() to let kprobe_flush_task() call. >>>>>>> define init_kretprobes() to let init_kprobes() call. >>>>>>> >>>>>>> The patch passes compiling (get "kernel/kprobes.o" and "kernel/built- >>>>>>> in.o") under avr32 and x86_64 allmodconfig, and passes building (get >>>>>>> bzImage and Modpost modules) under x86_64 defconfig. >>>>>> >>>>>> Thanks for the fix! and I have some comments below. >>>>>> >>>>>>> Signed-off-by: Chen Gang >>>>>>> --- >>>>>>> include/linux/kprobes.h | 58 +++++---- >>>>>>> kernel/kprobes.c | 328 +++++++++++++++++++++++++++--------------------- >>>>>>> 2 files changed, 222 insertions(+), 164 deletions(-) >>>>>>> >>>>>>> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h >>>>>>> index 925eaf2..c0d1212 100644 >>>>>>> --- a/include/linux/kprobes.h >>>>>>> +++ b/include/linux/kprobes.h >>>>>>> @@ -223,10 +223,36 @@ static inline int kprobes_built_in(void) >>>>>>> return 1; >>>>>>> } >>>>>>> >>>>>>> +int disable_kprobe(struct kprobe *kp); >>>>>>> +int enable_kprobe(struct kprobe *kp); >>>>>>> + >>>>>>> +void dump_kprobe(struct kprobe *kp); >>>>>>> + >>>>>>> +extern struct kretprobe_blackpoint kretprobe_blacklist[]; >>>>>>> + >>>>>>> #ifdef CONFIG_KRETPROBES >>>>>>> extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, >>>>>>> struct pt_regs *regs); >>>>>>> extern int arch_trampoline_kprobe(struct kprobe *p); >>>>>>> +static inline void kretprobe_assert(struct kretprobe_instance *ri, >>>>>>> + unsigned long orig_ret_address, unsigned long trampoline_address) >>>>>>> +{ >>>>>>> + if (!orig_ret_address || (orig_ret_address == trampoline_address)) { >>>>>>> + printk(KERN_ERR >>>>>>> + "kretprobe BUG!: Processing kretprobe %p @ %p\n", >>>>>>> + ri->rp, ri->rp->kp.addr); >>>>>>> + BUG(); >>>>>>> + } >>>>>>> +} >>>>>>> +static inline int disable_kretprobe(struct kretprobe *rp) >>>>>>> +{ >>>>>>> + return disable_kprobe(&rp->kp); >>>>>>> +} >>>>>>> +static inline int enable_kretprobe(struct kretprobe *rp) >>>>>>> +{ >>>>>>> + return enable_kprobe(&rp->kp); >>>>>>> +} >>>>>>> + >>>>>>> #else /* CONFIG_KRETPROBES */ >>>>>>> static inline void arch_prepare_kretprobe(struct kretprobe *rp, >>>>>>> struct pt_regs *regs) >>>>>>> @@ -236,19 +262,20 @@ static inline int arch_trampoline_kprobe(struct kprobe *p) >>>>>>> { >>>>>>> return 0; >>>>>>> } >>>>>>> -#endif /* CONFIG_KRETPROBES */ >>>>>>> - >>>>>>> -extern struct kretprobe_blackpoint kretprobe_blacklist[]; >>>>>>> - >>>>>>> static inline void kretprobe_assert(struct kretprobe_instance *ri, >>>>>>> unsigned long orig_ret_address, unsigned long trampoline_address) >>>>>>> { >>>>>>> - if (!orig_ret_address || (orig_ret_address == trampoline_address)) { >>>>>>> - printk("kretprobe BUG!: Processing kretprobe %p @ %p\n", >>>>>>> - ri->rp, ri->rp->kp.addr); >>>>>>> - BUG(); >>>>>>> - } >>>>>>> } >>>>>>> +static inline int disable_kretprobe(struct kretprobe *rp) >>>>>>> +{ >>>>>>> + return 0; >>>>>>> +} >>>>>>> +static inline int enable_kretprobe(struct kretprobe *rp) >>>>>>> +{ >>>>>>> + return 0; >>>>>>> +} >>>>>> >>>>>> No, these should returns -EINVAL or -ENOSYS, since these are user API. >>>>> >>>>> OK, thanks, it sounds reasonable to me. >>>>> >>>>>> Anyway, I don't think those inlined functions to be changed, because >>>>>> most of them are internal functions. If CONFIG_KRETPROBES=n, it just >>>>>> be ignored. >>>>>> >>>>> >>>>> In original implementation, if CONFIG_KRETPROBES=n, kretprobe_assert(), >>>>> disable_kretprobe(), and enable_kretprobe() are not ignored. >>>> >>>> Really? where are they called? I mean, those functions do not have >>>> any instance unless your module uses it (but that is not what the kernel >>>> itself should help). >>>> >>> >>> If what you said correct (I guess so), for me, we still need let them in >>> CONFIG_KRETPROBES area, and without any dummy outside, just like another >>> *kprobe* static inline functions have done in "include/linux/kprobes.h". >> >> kretprobe_assert() is only for the internal check. So we don't need to care >> about, and disable/enable_kretprobe() are anyway returns -EINVAL because >> kretprobe can not be registered. And all of them are inlined functions. >> In that case, we don't need to care about it. > > Hmm... it is related with code 'consistency': > > - these static inline functions are kretprobe generic implementation, > and we are trying to let all kretprobe generic implementation within > CONFIG_KRETPROBES area. No, actually, kretprobe is just built on the kprobe. enable/disable_kretprobe just wrapped the kprobe methods. And kretprobe_assert() is just for kretprobe internal use. that is not an API. Moving only the kretprobe_assert() into the CONFIG_KRETPROBE area is not bad, but since it is just a static inline function, if there is no caller, it just be ignored, no side effect. > > - And original kprobe static inline functions have done like that, > in same header file, if no obvious reasons, we can try to follow. It is no reasons to follow that too. Please keep your patch simple as much as possible. >> I just concerned that it is a waste of memory if there are useless kretprobe >> related instances are built when CONFIG_KRETPROBES=n. >> > > Yeah, that is also one of reason (3rd reason). > > > And if necessary, please help check what we have done whether already > "let all kretprobe generic implementation within CONFIG_KRETPROBES area" > (exclude declaration, struct/union definition, and architecture > implementation). As I commented, your changes in kernel/kprobes.c are good to me except two functions. That's all what we need to fix :) Thank you! -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/