From patchwork Thu May 7 10:00:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 11532975 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4B3181668 for ; Thu, 7 May 2020 10:00:46 +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 022992083B for ; Thu, 7 May 2020 10:00:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QBhwig8F"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="jbXz3wPT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 022992083B 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+patchwork-linux-arm=patchwork.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:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gS4CPa+xgBX5weVcqJf//Z+gbgZHKfZ09Dc+Px2Sv6c=; b=QBhwig8FCICxHq g6GpYvRvQkzL8PXVxFLYzg8/xvVLKvVob8QcGFfHDNqhJnzTlDRu3zHVd7dXk+Lc+nZjUH0N4UfFY 6pKEfCe0o/rcUzL9mUbODJ7MkvcIJmJCDDyst3qcjZ4EqLqvVbmKwwMDZxbyIX8bFyEMbHXBEG28F ut/VcVrpBk6vN1Ono65AHVy6kDzNBb+el3KsYHewHeMbfDM/9UCgHvzDgVzfa8GwkmrSj5yuJDZgZ qq99ENAF7T5N6Ziu9TWZaf6KUo5/AAWEvwzcNETlc5dvdXm/iyLz7mWFGmUYW7E4x4dEWrdAOWTsI nhMf0uy0ve6a8wVH7TRg==; 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 1jWdKZ-0007Em-Gw; Thu, 07 May 2020 10:00:41 +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 1jWdKB-0005B2-0e for linux-arm-kernel@lists.infradead.org; Thu, 07 May 2020 10:00:19 +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 D06CB20870; Thu, 7 May 2020 10:00:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588845614; bh=5sZJWMajUh4vPySqA51QTeZbNJXETHrWyOeQvUNxR3U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jbXz3wPTNC8shMt8HNhEp6VmaFXT3FAF2/SoA1Zyei0p2qSuYCzbOfonD8QsHuw2o Ab6IFebSzm6lvtRNC4Mf+U69s1y1xMPZhXgJBdQSn9pwM3ODnATl+Td0dUVu6rba0K qFOM/QT2mZ3A6ClvIPvir4MMiYtY7A4FOnceuH8g= From: Masami Hiramatsu To: LKML Subject: [RFC PATCH 2/3] arm64: kprobes: Support nested kprobes Date: Thu, 7 May 2020 19:00:07 +0900 Message-Id: <158884560738.12656.13619534422220572094.stgit@devnote2> X-Mailer: git-send-email 2.20.1 In-Reply-To: <158884558272.12656.7654266361809594662.stgit@devnote2> References: <158884558272.12656.7654266361809594662.stgit@devnote2> 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_030015_465674_9C0DFC15 X-CRM114-Status: GOOD ( 18.60 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender 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 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Make kprobes to accept 1-level nesting instead of missing it on arm64. 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, that will be missed. 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 ... sh-211 [005] d..2 71.708242: p_ring_buffer_lock_reserve_0: (ring_buffer_lock_reserve+0x0/0x4c8) sh-211 [005] d..2 71.709982: => kprobe_dispatcher => kprobe_breakpoint_handler => call_break_hook => brk_handler => do_debug_exception => el1_sync_handler => el1_sync => ring_buffer_lock_reserve => kprobe_trace_func => kprobe_dispatcher => kprobe_breakpoint_handler => call_break_hook => brk_handler => do_debug_exception => el1_sync_handler => el1_sync => vfs_read => __arm64_sys_read => el0_svc_common.constprop.3 => do_el0_svc => el0_sync_handler => el0_sync This shows brk_handler is nested. Signed-off-by: Masami Hiramatsu --- arch/arm64/include/asm/kprobes.h | 5 ++ arch/arm64/kernel/probes/kprobes.c | 75 ++++++++++++++++++++---------------- 2 files changed, 46 insertions(+), 34 deletions(-) diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h index 97e511d645a2..b2ebd3bad794 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h @@ -34,12 +34,15 @@ struct kprobe_step_ctx { unsigned long match_addr; }; +#define KPROBE_NEST_MAX 2 + /* per-cpu kprobe control block */ struct kprobe_ctlblk { unsigned int kprobe_status; unsigned long saved_irqflag; - struct prev_kprobe prev_kprobe; + struct prev_kprobe prev[KPROBE_NEST_MAX]; struct kprobe_step_ctx ss_ctx; + int nested; }; void arch_remove_kprobe(struct kprobe *); diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index d1c95dcf1d78..27d52726277b 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -153,14 +153,18 @@ void __kprobes arch_remove_kprobe(struct kprobe *p) static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) { - kcb->prev_kprobe.kp = kprobe_running(); - kcb->prev_kprobe.status = kcb->kprobe_status; + int i = kcb->nested++; + + kcb->prev[i].kp = kprobe_running(); + kcb->prev[i].status = kcb->kprobe_status; } static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) { - __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); - kcb->kprobe_status = kcb->prev_kprobe.status; + int i = --kcb->nested; + + __this_cpu_write(current_kprobe, kcb->prev[i].kp); + kcb->kprobe_status = kcb->prev[i].status; } static void __kprobes set_current_kprobe(struct kprobe *p) @@ -168,6 +172,14 @@ static void __kprobes set_current_kprobe(struct kprobe *p) __this_cpu_write(current_kprobe, p); } +static nokprobe_inline void pop_current_kprobe(struct kprobe_ctlblk *kcb) +{ + if (kcb->nested) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); +} + /* * Interrupts need to be disabled before single-step mode is set, and not * reenabled until after single-step mode ends. @@ -243,6 +255,10 @@ static int __kprobes reenter_kprobe(struct kprobe *p, switch (kcb->kprobe_status) { case KPROBE_HIT_SSDONE: case KPROBE_HIT_ACTIVE: + if (kcb->nested < KPROBE_NEST_MAX - 1) { + save_previous_kprobe(kcb); + return 0; + } kprobes_inc_nmissed_count(p); setup_singlestep(p, regs, kcb, 1); break; @@ -286,7 +302,7 @@ post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) cur->post_handler(cur, regs, 0); } - reset_current_kprobe(); + pop_current_kprobe(kcb); } int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) @@ -309,11 +325,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) BUG(); kernel_disable_single_step(); - - if (kcb->kprobe_status == KPROBE_REENTER) - restore_previous_kprobe(kcb); - else - reset_current_kprobe(); + pop_current_kprobe(kcb); break; case KPROBE_HIT_ACTIVE: @@ -357,30 +369,27 @@ static void __kprobes kprobe_handler(struct pt_regs *regs) p = get_kprobe((kprobe_opcode_t *) addr); if (p) { - if (cur_kprobe) { - if (reenter_kprobe(p, regs, kcb)) - return; - } else { - /* Probe hit */ - set_current_kprobe(p); - kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (cur_kprobe && reenter_kprobe(p, regs, kcb)) + return; + /* Probe hit */ + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; - /* - * If we have no pre-handler or it returned 0, we - * continue with normal processing. If we have a - * pre-handler and it returned non-zero, it will - * modify the execution path and no need to single - * stepping. Let's just reset current kprobe and exit. - * - * pre_handler can hit a breakpoint and can step thru - * before return, keep PSTATE D-flag enabled until - * pre_handler return back. - */ - if (!p->pre_handler || !p->pre_handler(p, regs)) { - setup_singlestep(p, regs, kcb, 0); - } else - reset_current_kprobe(); - } + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it will + * modify the execution path and no need to single + * stepping. Let's just reset current kprobe and exit. + * + * pre_handler can hit a breakpoint and can step thru + * before return, keep PSTATE D-flag enabled until + * pre_handler return back. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) { + setup_singlestep(p, regs, kcb, 0); + } else + pop_current_kprobe(kcb); } /* * The breakpoint instruction was removed right