From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754395AbbAGRPr (ORCPT ); Wed, 7 Jan 2015 12:15:47 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:39336 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754258AbbAGRPp (ORCPT ); Wed, 7 Jan 2015 12:15:45 -0500 Message-ID: <54AD69BE.6050007@codeaurora.org> Date: Wed, 07 Jan 2015 12:15:42 -0500 From: Christopher Covington User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:33.0) Gecko/20100101 Thunderbird/33.0 MIME-Version: 1.0 To: Wang Nan , linux@arm.linux.org.uk, mingo@redhat.com, x86@kernel.org, masami.hiramatsu.pt@hitachi.com, anil.s.keshavamurthy@intel.com, davem@davemloft.net, ananth@in.ibm.com, dave.long@linaro.org, tixy@linaro.org CC: lizefan@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH 01/11] ARM: kprobes: directly modify code if kprobe is not initialized. References: <1420616086-42692-1-git-send-email-wangnan0@huawei.com> <1420616124-42765-1-git-send-email-wangnan0@huawei.com> In-Reply-To: <1420616124-42765-1-git-send-email-wangnan0@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/07/2015 02:35 AM, Wang Nan wrote: > If kprobe is optimized before kprobe is initialized, there should > be only one core, the probed instruction is not armed with breakpoint, > so simply patch text is okay. > > Signed-off-by: Wang Nan > --- > arch/arm/probes/kprobes/opt-arm.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c > index 15b37c0..a021474 100644 > --- a/arch/arm/probes/kprobes/opt-arm.c > +++ b/arch/arm/probes/kprobes/opt-arm.c > @@ -325,8 +325,17 @@ void __kprobes arch_optimize_kprobes(struct list_head *oplist) > * Similar to __arch_disarm_kprobe, operations which > * removing breakpoints must be wrapped by stop_machine > * to avoid racing. > + * > + * If this function is called before kprobes initialized, > + * the kprobe should be an early kprobe, the instruction > + * is not armed with breakpoint. There should be only > + * one core now, so directly __patch_text is enough. > */ > - kprobes_remove_breakpoint(op->kp.addr, insn); > + if (unlikely(!kprobes_initialized)) { > + BUG_ON(!(op->kp.flags & KPROBE_FLAG_EARLY)); > + __patch_text(op->kp.addr, insn); > + } else > + kprobes_remove_breakpoint(op->kp.addr, insn); "...if only one branch of a conditional statement is a single statement ... use braces in both branches". https://www.kernel.org/doc/Documentation/CodingStyle > > list_del_init(&op->list); > } > Regards, Chris -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project