Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753487AbaBDPjq (ORCPT ); Tue, 4 Feb 2014 10:39:46 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:43958 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaBDPjm (ORCPT ); Tue, 4 Feb 2014 10:39:42 -0500 Message-ID: <52F109AF.8040800@hitachi.com> Date: Wed, 05 Feb 2014 00:39:27 +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> In-Reply-To: <52F0F0ED.5090005@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 (2014/02/04 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. I just concerned that it is a waste of memory if there are useless kretprobe related instances are built when CONFIG_KRETPROBES=n. Thank you, >>> >>>> So, I think you don't need to change kprobes.h. >>>> >>> >>> So "kprobes.h" still need be changed. >> >> Is there any concrete problem you have? >> > > No, I just read the code, no additional really issues. > > > Thanks. > -- 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/