From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5449DC2D0C0 for ; Mon, 23 Dec 2019 12:39:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 08D6020715 for ; Mon, 23 Dec 2019 12:39:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726763AbfLWMjY (ORCPT ); Mon, 23 Dec 2019 07:39:24 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:8163 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726257AbfLWMjY (ORCPT ); Mon, 23 Dec 2019 07:39:24 -0500 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id C0920572CCF3A64A2C29; Mon, 23 Dec 2019 20:39:20 +0800 (CST) Received: from [127.0.0.1] (10.133.217.236) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.439.0; Mon, 23 Dec 2019 20:39:12 +0800 Subject: Re: [PATCH] arm64/kprobe: add support for KPROBES_ON_FTRACE To: , CC: , , , , , References: <20191223123828.39543-1-cj.chengjian@huawei.com> From: "chengjian (D)" Message-ID: Date: Mon, 23 Dec 2019 20:39:10 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20191223123828.39543-1-cj.chengjian@huawei.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.133.217.236] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I am SORRY. I searched on patchwork and found this : arm64: implement KPROBES_ON_FTRACE https://lore.kernel.org/patchwork/patch/1169445/ So please ignore my EMAIL. Thank you. ---- Cheng Jian On 2019/12/23 20:38, Cheng Jian wrote: > Allow KPROBES to use the ftrace infrastructure. > This depends on HAVE_DYNAMIC_FTRACE_WITH_REGS > which introduce by : > commit 3b23e4991fb6 ("arm64: implement ftrace with regs") > > Based on the x86 code by Masami. > > With: > # cd /sys/kernel/debug/tracing > # echo 'p _do_fork+0x4' > kprobe_events > > before patch: > # cat ../kprobes/list > sh: write error: Invalid argument > > after patch: > # cat ../kprobes/list > ffffa00016aa9d4c k _do_fork+0x4 [FTRACE] > > Signed-off-by: Cheng Jian > --- > .../debug/kprobes-on-ftrace/arch-support.txt | 2 +- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/probes/Makefile | 2 + > arch/arm64/kernel/probes/ftrace.c | 65 +++++++++++++++++++ > 4 files changed, 69 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/kernel/probes/ftrace.c > > diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt > index 4fae0464ddff..f9dd9dd91e0c 100644 > --- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt > +++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt > @@ -9,7 +9,7 @@ > | alpha: | TODO | > | arc: | TODO | > | arm: | TODO | > - | arm64: | TODO | > + | arm64: | ok | > | c6x: | TODO | > | csky: | TODO | > | h8300: | TODO | > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index b1b4476ddb83..d613be9c2346 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -144,6 +144,7 @@ config ARM64 > select HAVE_DYNAMIC_FTRACE > select HAVE_DYNAMIC_FTRACE_WITH_REGS \ > if $(cc-option,-fpatchable-function-entry=2) > + select HAVE_KPROBES_ON_FTRACE if HAVE_DYNAMIC_FTRACE_WITH_REGS > select HAVE_EFFICIENT_UNALIGNED_ACCESS > select HAVE_FAST_GUP > select HAVE_FTRACE_MCOUNT_RECORD > diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile > index 8e4be92e25b1..45a9d916a47d 100644 > --- a/arch/arm64/kernel/probes/Makefile > +++ b/arch/arm64/kernel/probes/Makefile > @@ -4,3 +4,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \ > simulate-insn.o > obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \ > simulate-insn.o > + > +obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o > diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/ftrace.c > new file mode 100644 > index 000000000000..f89bfaa3e5f3 > --- /dev/null > +++ b/arch/arm64/kernel/probes/ftrace.c > @@ -0,0 +1,65 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Dynamic Ftrace based Kprobes Optimization > + * > + * Copyright (C) Hitachi Ltd., 2012 > + * Copyright (C) 2019 Huawei Inc. > + * Copyright 2019 Cheng Jian > + */ > +#include > +#include > +#include > +#include > +#include > + > + > +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ > +void kprobe_ftrace_handler(unsigned long pc, unsigned long parent_pc, > + struct ftrace_ops *ops, struct pt_regs *regs) > +{ > + struct kprobe *p; > + struct kprobe_ctlblk *kcb; > + > + /* Preempt is disabled by ftrace */ > + p = get_kprobe((kprobe_opcode_t *)pc); > + if (unlikely(!p) || kprobe_disabled(p)) > + return; > + > + kcb = get_kprobe_ctlblk(); > + if (kprobe_running()) { > + kprobes_inc_nmissed_count(p); > + } else { > + /* > + * On ARM64, recg->pc is *before* this instruction for the > + * pre handler. > + */ > + regs->pc -= MCOUNT_INSN_SIZE; > + > + __this_cpu_write(current_kprobe, p); > + kcb->kprobe_status = KPROBE_HIT_ACTIVE; > + if (!p->pre_handler || !p->pre_handler(p, regs)) { > + /* > + * Emulate singlestep (and also recover regs->ip) > + * as if there is a nop > + */ > + regs->pc += MCOUNT_INSN_SIZE; > + if (unlikely(p->post_handler)) { > + kcb->kprobe_status = KPROBE_HIT_SSDONE; > + p->post_handler(p, regs, 0); > + } > + } > + /* > + * If pre_handler returns !0, it changes regs->ip. We have to > + * skip emulating post_handler. > + */ > + __this_cpu_write(current_kprobe, NULL); > + } > +} > +NOKPROBE_SYMBOL(kprobe_ftrace_handler); > + > +int arch_prepare_kprobe_ftrace(struct kprobe *p) > +{ > + p->ainsn.api.insn = NULL; > + > + return 0; > +}