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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no 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 55E86C38A24 for ; Thu, 7 May 2020 09:59:55 +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 2701120870 for ; Thu, 7 May 2020 09:59:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="W3M7FPdm"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1aUldhiQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2701120870 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:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=Xqio4q8H3ijZUCvDtXPxiN/Za475z0T10mofspdC1vE=; b=W3M7FPdmfWjeLB vmLZwSPRvM8ylNTQ53JP1RrrzMunfsawn9daCAEKUwz+tFuCczVQ9VBNuUO5w7ZwOIR6/wxaLf/dh 0hrJR6hbIkwB7qpd8HT7K1Aw1CWWFoygPCZepsj2/KMh0OviUxUFq0IgDIA2gCjYc+b6DMfe+/xgZ nCnDVFjf6IfenIUA/myrjUaZO3wjVVtVraxqSHXyKoSrsEOztO5OJLyBoQ6yhi87m26GTpuD65fln kIQFAlN4hm5jS+VFrMkggiBIL7f+h6MSX8KSop4RwwSm2ZpqCALUkAOfvgUBS1jwxuMgKFedgyyAa JCICulu/+xdARdBb4F9g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWdJq-0003Xd-KA; Thu, 07 May 2020 09:59:54 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWdJo-0003Wv-0L for linux-arm-kernel@lists.infradead.org; Thu, 07 May 2020 09:59:53 +0000 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9027C20643; Thu, 7 May 2020 09:59:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588845589; bh=1dH5G1leAYENAhuCpe5L02sl2FX0JniYY4i2b+iiscs=; h=From:To:Cc:Subject:Date:From; b=1aUldhiQbHoUUq98QeyZox9aJSM7fUex2qh2uKAqXjx1zIHigKYWqndTApyZ8Q6h+ kmOaWmRVk1MiImGIY8H0404e2ryIMSTusCdfZi2zrrVtdCKI+4inXLc8iYKXrGtO// UKpQuhTXij4WrjkTmPbAG530abAmO1w29UVHXsHQ= From: Masami Hiramatsu To: LKML Subject: [RFC PATCH 0/3] kprobes: Support nested kprobes Date: Thu, 7 May 2020 18:59:42 +0900 Message-Id: <158884558272.12656.7654266361809594662.stgit@devnote2> X-Mailer: git-send-email 2.20.1 User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200507_025952_095643_C779BEDA X-CRM114-Status: GOOD ( 11.73 ) 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: Wang Nan , Song Liu , Martin KaFai Lau , Daniel Borkmann , Russell King , Network Development , Alexei Starovoitov , Arnaldo Carvalho de Melo , "David S . Miller" , Will Deacon , Steven Rostedt , Catalin Marinas , Yonghong Song , bpf , Andrii Nakryiko , Ingo Molnar , linux-arm-kernel@lists.infradead.org, Eelco Chaudron 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, Here is a series to add nested-kprobes support to x86, arm64 and arm (which I can test). These make kprobes to accept 1-level nesting instead of incrementing missed count. Any kprobes hits in kprobes pre/post handler context can be nested at once. If the other kprobes hits in the nested pre/post handler context or in the single-stepping context, that will be still missed. The nest level is actually easily extended, but too many nest level can lead the overflow of the kernel stack (for each nest, the stack will be consumed by saving registers, handling kprobes and pre/post handlers.) Thus, at this moment it allows only one level nest. This feature allows BPF or ftrace user to put a kprobe on BPF jited code or ftrace internal code running in the kprobe context for debugging. We can test this feature on the kernel with CONFIG_KPROBE_EVENTS_ON_NOTRACE=y as below. # cd /sys/kernel/debug/tracing # echo p ring_buffer_lock_reserve > kprobe_events # echo p vfs_read >> kprobe_events # echo stacktrace > events/kprobes/p_ring_buffer_lock_reserve_0/trigger # echo 1 > events/kprobes/enable # cat trace ... cat-151 [000] ...1 48.669190: p_vfs_read_0: (vfs_read+0x0/0x160) cat-151 [000] ...2 48.669276: p_ring_buffer_lock_reserve_0: (ring_buffer_lock_reserve+0x0/0x400) cat-151 [000] ...2 48.669288: => kprobe_dispatcher => opt_pre_handler => optimized_callback => 0xffffffffa0002331 => ring_buffer_lock_reserve => kprobe_trace_func => kprobe_dispatcher => opt_pre_handler => optimized_callback => 0xffffffffa00023b0 => vfs_read => load_elf_phdrs => load_elf_binary => search_binary_handler.part.0 => __do_execve_file.isra.0 => __x64_sys_execve => do_syscall_64 => entry_SYSCALL_64_after_hwframe To check unoptimized code, disable optprobe and dump the log. # echo 0 > /proc/sys/debug/kprobes-optimization # echo > trace # cat trace cat-153 [000] d..1 140.581433: p_vfs_read_0: (vfs_read+0x0/0x160) cat-153 [000] d..2 140.581780: p_ring_buffer_lock_reserve_0: (ring_buffer_lock_reserve+0x0/0x400) cat-153 [000] d..2 140.581811: => kprobe_dispatcher => aggr_pre_handler => kprobe_int3_handler => do_int3 => int3 => ring_buffer_lock_reserve => kprobe_trace_func => kprobe_dispatcher => aggr_pre_handler => kprobe_int3_handler => do_int3 => int3 => vfs_read => load_elf_phdrs => load_elf_binary => search_binary_handler.part.0 => __do_execve_file.isra.0 => __x64_sys_execve => do_syscall_64 => entry_SYSCALL_64_after_hwframe So we can see the kprobe can be nested. Thank you, --- Masami Hiramatsu (3): x86/kprobes: Support nested kprobes arm64: kprobes: Support nested kprobes arm: kprobes: Support nested kprobes arch/arm/include/asm/kprobes.h | 5 ++ arch/arm/probes/kprobes/core.c | 79 ++++++++++++++---------------- arch/arm/probes/kprobes/core.h | 30 +++++++++++ arch/arm/probes/kprobes/opt-arm.c | 6 ++ arch/arm64/include/asm/kprobes.h | 5 ++ arch/arm64/kernel/probes/kprobes.c | 75 ++++++++++++++++------------ arch/x86/include/asm/kprobes.h | 5 ++ arch/x86/kernel/kprobes/common.h | 39 ++++++++++++++- arch/x86/kernel/kprobes/core.c | 96 +++++++++++++++--------------------- arch/x86/kernel/kprobes/ftrace.c | 6 ++ arch/x86/kernel/kprobes/opt.c | 13 +++-- 11 files changed, 214 insertions(+), 145 deletions(-) -- Masami Hiramatsu (Linaro) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel