From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754281AbaBEASr (ORCPT ); Tue, 4 Feb 2014 19:18:47 -0500 Received: from mail-pd0-f170.google.com ([209.85.192.170]:39683 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750716AbaBEASp (ORCPT ); Tue, 4 Feb 2014 19:18:45 -0500 Message-ID: <52F18367.2060803@gmail.com> Date: Wed, 05 Feb 2014 08:18:47 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Masami Hiramatsu 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> In-Reply-To: <52F109AF.8040800@hitachi.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 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. - And original kprobe static inline functions have done like that, in same header file, if no obvious reasons, we can try to follow. > 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). > Thank you, > Thanks. -- Chen Gang Open, share and attitude like air, water and life which God blessed