From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Subject: Re: [RFC PATCH -tip v5 18/27] powerpc/kprobes: Don't call the ->break_handler() in arm kprobes code Date: Thu, 7 Jun 2018 23:28:02 +0900 Message-ID: <20180607232802.c5fcea960e94ef2f3cd4cde8@kernel.org> References: <152812730943.10068.5166429445118734697.stgit@devbox> <152812783350.10068.4690566636762511152.stgit@devbox> <1528371112.vwnh1m0k39.naveen@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1528371112.vwnh1m0k39.naveen@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: "Naveen N. Rao" Cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , "H . Peter Anvin" , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Paul Mackerras , Steven Rostedt List-Id: linux-arch.vger.kernel.org On Thu, 07 Jun 2018 17:07:00 +0530 "Naveen N. Rao" wrote: > Masami Hiramatsu wrote: > > Don't call the ->break_handler() from the arm kprobes code, > ^^^ powerpc > > > because it was only used by jprobes which got removed. > > > > This also makes skip_singlestep() a static function since > > only ftrace-kprobe.c is using this function. > > > > Signed-off-by: Masami Hiramatsu > > Cc: Benjamin Herrenschmidt > > Cc: Paul Mackerras > > Cc: Michael Ellerman > > Cc: "Naveen N. Rao" > > Cc: linuxppc-dev@lists.ozlabs.org > > --- > > arch/powerpc/include/asm/kprobes.h | 10 ---------- > > arch/powerpc/kernel/kprobes-ftrace.c | 16 +++------------- > > arch/powerpc/kernel/kprobes.c | 31 +++++++++++-------------------- > > 3 files changed, 14 insertions(+), 43 deletions(-) > > With 2 small comments... 2 ? or 1 ? > Acked-by: Naveen N. Rao > > - Naveen > > > > > diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h > > index 674036db558b..785c464b6588 100644 > > --- a/arch/powerpc/include/asm/kprobes.h > > +++ b/arch/powerpc/include/asm/kprobes.h > > @@ -102,16 +102,6 @@ extern int kprobe_exceptions_notify(struct notifier_block *self, > > extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); > > extern int kprobe_handler(struct pt_regs *regs); > > extern int kprobe_post_handler(struct pt_regs *regs); > > -#ifdef CONFIG_KPROBES_ON_FTRACE > > -extern int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb); > > -#else > > -static inline int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb) > > -{ > > - return 0; > > -} > > -#endif > > #else > > static inline int kprobe_handler(struct pt_regs *regs) { return 0; } > > static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; } > > diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c > > index 1b316331c2d9..3869b0e5d5c7 100644 > > --- a/arch/powerpc/kernel/kprobes-ftrace.c > > +++ b/arch/powerpc/kernel/kprobes-ftrace.c > > @@ -26,8 +26,8 @@ > > #include > > > > static nokprobe_inline > > -int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb, unsigned long orig_nip) > > +int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > + struct kprobe_ctlblk *kcb, unsigned long orig_nip) > > { > > /* > > * Emulate singlestep (and also recover regs->nip) > > @@ -44,16 +44,6 @@ int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > return 1; > > } > > > > -int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb) > > -{ > > - if (kprobe_ftrace(p)) > > - return __skip_singlestep(p, regs, kcb, 0); > > - else > > - return 0; > > -} > > -NOKPROBE_SYMBOL(skip_singlestep); > > - > > /* Ftrace callback handler for kprobes */ > > void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, > > struct ftrace_ops *ops, struct pt_regs *regs) > > @@ -82,7 +72,7 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, > > __this_cpu_write(current_kprobe, p); > > kcb->kprobe_status = KPROBE_HIT_ACTIVE; > > if (!p->pre_handler || !p->pre_handler(p, regs)) > > - __skip_singlestep(p, regs, kcb, orig_nip); > > + skip_singlestep(p, regs, kcb, orig_nip); > > We can probably get rid of skip_singlestep() completely along with > orig_nip since instructions are always 4 bytes on powerpc. So, the > changes we do to nip should help to recover the value automatically. Good point! Yes, skip_singlestep() is no more exported, so we just consolidate it into kprobe_ftrace_handler() for simplifying operation. Thank you! > > - Naveen > > -- Masami Hiramatsu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:47170 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933109AbeFGO2F (ORCPT ); Thu, 7 Jun 2018 10:28:05 -0400 Date: Thu, 7 Jun 2018 23:28:02 +0900 From: Masami Hiramatsu Subject: Re: [RFC PATCH -tip v5 18/27] powerpc/kprobes: Don't call the ->break_handler() in arm kprobes code Message-ID: <20180607232802.c5fcea960e94ef2f3cd4cde8@kernel.org> In-Reply-To: <1528371112.vwnh1m0k39.naveen@linux.ibm.com> References: <152812730943.10068.5166429445118734697.stgit@devbox> <152812783350.10068.4690566636762511152.stgit@devbox> <1528371112.vwnh1m0k39.naveen@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Naveen N. Rao" Cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , "H . Peter Anvin" , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Paul Mackerras , Steven Rostedt Message-ID: <20180607142802._vApYMIScU_4h2jUnHbEtu9PSKVAVIpMIqeZn8PKIls@z> On Thu, 07 Jun 2018 17:07:00 +0530 "Naveen N. Rao" wrote: > Masami Hiramatsu wrote: > > Don't call the ->break_handler() from the arm kprobes code, > ^^^ powerpc > > > because it was only used by jprobes which got removed. > > > > This also makes skip_singlestep() a static function since > > only ftrace-kprobe.c is using this function. > > > > Signed-off-by: Masami Hiramatsu > > Cc: Benjamin Herrenschmidt > > Cc: Paul Mackerras > > Cc: Michael Ellerman > > Cc: "Naveen N. Rao" > > Cc: linuxppc-dev@lists.ozlabs.org > > --- > > arch/powerpc/include/asm/kprobes.h | 10 ---------- > > arch/powerpc/kernel/kprobes-ftrace.c | 16 +++------------- > > arch/powerpc/kernel/kprobes.c | 31 +++++++++++-------------------- > > 3 files changed, 14 insertions(+), 43 deletions(-) > > With 2 small comments... 2 ? or 1 ? > Acked-by: Naveen N. Rao > > - Naveen > > > > > diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h > > index 674036db558b..785c464b6588 100644 > > --- a/arch/powerpc/include/asm/kprobes.h > > +++ b/arch/powerpc/include/asm/kprobes.h > > @@ -102,16 +102,6 @@ extern int kprobe_exceptions_notify(struct notifier_block *self, > > extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); > > extern int kprobe_handler(struct pt_regs *regs); > > extern int kprobe_post_handler(struct pt_regs *regs); > > -#ifdef CONFIG_KPROBES_ON_FTRACE > > -extern int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb); > > -#else > > -static inline int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb) > > -{ > > - return 0; > > -} > > -#endif > > #else > > static inline int kprobe_handler(struct pt_regs *regs) { return 0; } > > static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; } > > diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c > > index 1b316331c2d9..3869b0e5d5c7 100644 > > --- a/arch/powerpc/kernel/kprobes-ftrace.c > > +++ b/arch/powerpc/kernel/kprobes-ftrace.c > > @@ -26,8 +26,8 @@ > > #include > > > > static nokprobe_inline > > -int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb, unsigned long orig_nip) > > +int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > + struct kprobe_ctlblk *kcb, unsigned long orig_nip) > > { > > /* > > * Emulate singlestep (and also recover regs->nip) > > @@ -44,16 +44,6 @@ int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > return 1; > > } > > > > -int skip_singlestep(struct kprobe *p, struct pt_regs *regs, > > - struct kprobe_ctlblk *kcb) > > -{ > > - if (kprobe_ftrace(p)) > > - return __skip_singlestep(p, regs, kcb, 0); > > - else > > - return 0; > > -} > > -NOKPROBE_SYMBOL(skip_singlestep); > > - > > /* Ftrace callback handler for kprobes */ > > void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, > > struct ftrace_ops *ops, struct pt_regs *regs) > > @@ -82,7 +72,7 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, > > __this_cpu_write(current_kprobe, p); > > kcb->kprobe_status = KPROBE_HIT_ACTIVE; > > if (!p->pre_handler || !p->pre_handler(p, regs)) > > - __skip_singlestep(p, regs, kcb, orig_nip); > > + skip_singlestep(p, regs, kcb, orig_nip); > > We can probably get rid of skip_singlestep() completely along with > orig_nip since instructions are always 4 bytes on powerpc. So, the > changes we do to nip should help to recover the value automatically. Good point! Yes, skip_singlestep() is no more exported, so we just consolidate it into kprobe_ftrace_handler() for simplifying operation. Thank you! > > - Naveen > > -- Masami Hiramatsu