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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 0A360C3A5A3 for ; Fri, 23 Aug 2019 14:57:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D203422CEC for ; Fri, 23 Aug 2019 14:57:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qfQgV0kF"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="yCgfe4zp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D203422CEC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To: Message-Id:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3EGKVOBoKmqiwfJcoixDDo8wjf/gMRjx2KA/IOmEUe0=; b=qfQgV0kFtxubMh uJVI1uNhkJF8cm+6IrcJyft9Q0rUcLKR7a210mnOTEgnG8YkpNruOhV9GGrCAQePCb5IWIX9NaOW0 eCI81T8YQn/xhgOBobscrzRp8ELeOswjkANRwFtdl5DcPsas8cOE7TGkIbYzKv/Dhi7s+iiKqpDVl EmrzI1mrjgjmH+gQHGpVkIzUSy3UgY2OnYvcIrAoH6A+NKGHYo0iY+alcWOX3Nio7JHYqEH7/VeRY KHh8gohQwqU2CxOvPHuk6JEq/2d4KsbVOguuul6v5EydBMx1kBvY7152OPy2muYcy8DBJFFUH+IPT HcJawQE+pz3RVuNKGBXg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i1B0M-00063A-Gu; Fri, 23 Aug 2019 14:57:30 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i1B0I-00062L-90 for linux-arm-kernel@lists.infradead.org; Fri, 23 Aug 2019 14:57:28 +0000 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3128B22CE3; Fri, 23 Aug 2019 14:57:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566572245; bh=nGyHVGYJBOvLh/YCjAm/19L+X2rQRKDPdrvRJJNSXuY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=yCgfe4zpT8YrkttAdUN3y4hg/Ifyy1eVlbHEVOaPdGHQkit/cwgzI5NfNDg7j0Ba0 KJDFaBx3YCLilzz4JR4n7AK0RXWxoC4x9/U8ywLS0eXKGRjfPj1/9bnQIcSbjzoU9v PNNnSoMRygN5+Sbt/CHba375XEK/XYx1fHjTbgFw= Date: Fri, 23 Aug 2019 23:57:21 +0900 From: Masami Hiramatsu To: Jisheng Zhang Subject: Re: [PATCH v5] arm64: implement KPROBES_ON_FTRACE Message-Id: <20190823235721.fa481fca3475a3afd92c740c@kernel.org> In-Reply-To: <20190822191351.3796aca8@xhacker.debian> References: <20190822191351.3796aca8@xhacker.debian> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190823_075726_355152_2CC3D43A X-CRM114-Status: GOOD ( 28.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Jonathan Corbet , Peter Zijlstra , Catalin Marinas , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Steven Rostedt , "Naveen N. Rao" , Will Deacon , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Jisheng, On Thu, 22 Aug 2019 11:25:00 +0000 Jisheng Zhang wrote: > KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it > eliminates the need for a trap, as well as the need to emulate or > single-step instructions. > > Tested on berlin arm64 platform. > > ~ # mount -t debugfs debugfs /sys/kernel/debug/ > ~ # cd /sys/kernel/debug/ > /sys/kernel/debug # echo 'p _do_fork' > tracing/kprobe_events > > before the patch: > > /sys/kernel/debug # cat kprobes/list > ffffff801009fe28 k _do_fork+0x0 [DISABLED] > > after the patch: > > /sys/kernel/debug # cat kprobes/list > ffffff801009ff54 k _do_fork+0x4 [DISABLED][FTRACE] > > Signed-off-by: Jisheng Zhang Looks good to me. Acked-by: Masami Hiramatsu Thank you, > --- > > KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it > eliminates the need for a trap, as well as the need to emulate or > single-step instructions. > > Applied after arm64 FTRACE_WITH_REGS: > http://lists.infradead.org/pipermail/linux-arm-kernel/2019-August/674404.html > > Changes since v4: > - correct reg->pc: probed on foo, then pre_handler see foo+0x4, while > post_handler see foo+0x8 > > Changes since v3: > - move kprobe_lookup_name() and arch_kprobe_on_func_entry to ftrace.c since > we only want to choose the ftrace entry for KPROBES_ON_FTRACE. > - only choose ftrace entry if (addr && !offset) > > Changes since v2: > - remove patch1, make it a single cleanup patch > - remove "This patch" in the change log > - implement arm64's kprobe_lookup_name() and arch_kprobe_on_func_entry instead > of patching the common kprobes code > > Changes since v1: > - make the kprobes/x86: use instruction_pointer and instruction_pointer_set > as patch1 > - add Masami's ACK to patch1 > - add some description about KPROBES_ON_FTRACE and why we need it on > arm64 > - correct the log before the patch > - remove the consolidation patch, make it as TODO > - only adjust kprobe's addr when KPROBE_FLAG_FTRACE is set > - if KPROBES_ON_FTRACE, ftrace_call_adjust() the kprobe's addr before > calling ftrace_location() > - update the kprobes-on-ftrace/arch-support.txt in doc > > .../debug/kprobes-on-ftrace/arch-support.txt | 2 +- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/probes/Makefile | 1 + > arch/arm64/kernel/probes/ftrace.c | 83 +++++++++++++++++++ > 4 files changed, 86 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 68f266944d5f..e8358a38981c 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 663392d1eae2..928700f15e23 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -167,6 +167,7 @@ config ARM64 > select HAVE_STACKPROTECTOR > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_KPROBES > + select HAVE_KPROBES_ON_FTRACE > select HAVE_KRETPROBES > select HAVE_GENERIC_VDSO > select IOMMU_DMA if IOMMU_SUPPORT > diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile > index 8e4be92e25b1..4020cfc66564 100644 > --- a/arch/arm64/kernel/probes/Makefile > +++ b/arch/arm64/kernel/probes/Makefile > @@ -4,3 +4,4 @@ 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..9f80905f02fa > --- /dev/null > +++ b/arch/arm64/kernel/probes/ftrace.c > @@ -0,0 +1,83 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Dynamic Ftrace based Kprobes Optimization > + * > + * Copyright (C) Hitachi Ltd., 2012 > + * Copyright (C) 2019 Jisheng Zhang > + * Synaptics Incorporated > + */ > + > +#include > + > +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ > +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, > + 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 *)ip); > + if (unlikely(!p) || kprobe_disabled(p)) > + return; > + > + kcb = get_kprobe_ctlblk(); > + if (kprobe_running()) { > + kprobes_inc_nmissed_count(p); > + } else { > + unsigned long orig_ip = instruction_pointer(regs); > + > + instruction_pointer_set(regs, ip); > + __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->pc) > + * as if there is a nop > + */ > + instruction_pointer_set(regs, > + (unsigned long)p->addr + MCOUNT_INSN_SIZE); > + if (unlikely(p->post_handler)) { > + kcb->kprobe_status = KPROBE_HIT_SSDONE; > + p->post_handler(p, regs, 0); > + } > + instruction_pointer_set(regs, orig_ip); > + } > + /* > + * If pre_handler returns !0, it changes regs->pc. We have to > + * skip emulating post_handler. > + */ > + __this_cpu_write(current_kprobe, NULL); > + } > +} > +NOKPROBE_SYMBOL(kprobe_ftrace_handler); > + > +kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) > +{ > + unsigned long addr = kallsyms_lookup_name(name); > + > + if (addr && !offset) { > + unsigned long faddr; > + /* > + * with -fpatchable-function-entry=2, the first 4 bytes is the > + * LR saver, then the actual call insn. So ftrace location is > + * always on the first 4 bytes offset. > + */ > + faddr = ftrace_location_range(addr, > + addr + AARCH64_INSN_SIZE); > + if (faddr) > + return (kprobe_opcode_t *)faddr; > + } > + return (kprobe_opcode_t *)addr; > +} > + > +bool arch_kprobe_on_func_entry(unsigned long offset) > +{ > + return offset <= AARCH64_INSN_SIZE; > +} > + > +int arch_prepare_kprobe_ftrace(struct kprobe *p) > +{ > + p->ainsn.api.insn = NULL; > + return 0; > +} > -- > 2.23.0.rc1 > -- Masami Hiramatsu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel