From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757939AbbCDCaj (ORCPT ); Tue, 3 Mar 2015 21:30:39 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:25330 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756583AbbCDCai (ORCPT ); Tue, 3 Mar 2015 21:30:38 -0500 Message-ID: <54F66E40.3010305@huawei.com> Date: Wed, 4 Mar 2015 10:30:24 +0800 From: Wang Nan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: , , , , CC: , , , Subject: Re: [RFC PATCH v4 27/34] early kprobes on ftrace: kprobe_on_ftrace_get_old_insn() References: <1425306312-3437-1-git-send-email-wangnan0@huawei.com> <1425306312-3437-28-git-send-email-wangnan0@huawei.com> In-Reply-To: <1425306312-3437-28-git-send-email-wangnan0@huawei.com> Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.69.129] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.54F66E4C.016B,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 1057391ee90e100f34cd671380a46b4f Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015/3/2 22:25, Wang Nan wrote: > Newly introduced function kprobe_on_ftrace_get_old_insn() will be > called by ftrace when ftrace generating call instruction. It is for > retriving probed instructions which original nops are replaced by > kprobe. FTRACE_FL_EARLY_KPROBES bit in rec->flags is cleared, so after > calling kprobe_on_ftrace_get_old_insn() an ftrace record will not be > treated as early kprobed. > > Signed-off-by: Wang Nan > --- > include/linux/kprobes.h | 9 +++++++++ > kernel/kprobes.c | 34 ++++++++++++++++++++++++++++++++++ > 2 files changed, 43 insertions(+) > > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > index 5a5290f..2d78bbb 100644 > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -289,6 +289,8 @@ extern const unsigned char *arch_kprobe_on_ftrace_get_old_insn(struct kprobe *kp > > extern void init_kprobes_on_ftrace(void); > extern bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec); > +extern const unsigned char *kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, > + const unsigned char *ftrace_nop, unsigned char *dest, size_t insn_size); > #else > static inline void init_kprobes_on_ftrace(void) > { > @@ -299,6 +301,13 @@ static inline bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *_unused) > > return false; > } > + > +static inline const unsigned char * > +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *_unused, > + const unsigned char *ftrace_nop, unsigned char *_unused2, size_t _unused3) > +{ > + return ftrace_nop; > +} > #endif // CONFIG_EARLY_KPROBES && CONFIG_KPROBES_ON_FTRACE > > #ifdef CONFIG_EARLY_KPROBES > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 20b6ab8..c504c1c 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2623,6 +2623,40 @@ bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec) > return true; > } > > +/* NOTE: caller must ensure holding kprobe_mutex */ > +const unsigned char * > +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, > + const unsigned char *ftrace_nop, > + unsigned char *dest, size_t insn_size) > +{ > + const unsigned char *ret; > + struct kprobe *kp; > + void *addr; > + > + if (!(rec->flags & FTRACE_FL_EARLY_KPROBES)) > + return ftrace_nop; > + > + addr = (void *)rec->ip; > + > + /* > + * Note that get_kprobe always get the kprobe on table, for it > + * KPROBE_FLAG_OPTIMIZED is reliable. > + */ > + kp = get_kprobe(addr); > + > + if (!kp || !(kp->flags & KPROBE_FLAG_FTRACE_EARLY)) { > + mutex_unlock(&kprobe_mutex); This mutex_unlock() is buggy. I'll fix it in next version. > + return ftrace_nop; > + } > + > + ret = arch_kprobe_on_ftrace_get_old_insn(kp, ftrace_nop, > + dest, insn_size); > + > + /* Only give one chance for kprobe to retrive old insn. */ > + rec->flags &= ~FTRACE_FL_EARLY_KPROBES; > + return ret; > +} > + > void init_kprobes_on_ftrace(void) > { > kprobes_on_ftrace_initialized = true; >