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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 B3E28C282DD for ; Wed, 8 Jan 2020 19:47:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8ED2F2070E for ; Wed, 8 Jan 2020 19:47:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730527AbgAHTqJ (ORCPT ); Wed, 8 Jan 2020 14:46:09 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43400 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730382AbgAHTqB (ORCPT ); Wed, 8 Jan 2020 14:46:01 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1ipHHC-0006nu-54; Wed, 08 Jan 2020 19:45:58 +0000 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1ipHHB-007dlU-DW; Wed, 08 Jan 2020 19:45:57 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Arnd Bergmann" , "James Morse" , "Will Deacon" Date: Wed, 08 Jan 2020 19:43:11 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 13/63] arm64: mm: Add trace_irqflags annotations to do_debug_exception() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.81-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: James Morse commit 6afedcd23cfd7ac56c011069e4a8db37b46e4623 upstream. With CONFIG_PROVE_LOCKING, CONFIG_DEBUG_LOCKDEP and CONFIG_TRACE_IRQFLAGS enabled, lockdep will compare current->hardirqs_enabled with the flags from local_irq_save(). When a debug exception occurs, interrupts are disabled in entry.S, but lockdep isn't told, resulting in: DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) ------------[ cut here ]------------ WARNING: at ../kernel/locking/lockdep.c:3523 Modules linked in: CPU: 3 PID: 1752 Comm: perf Not tainted 4.5.0-rc4+ #2204 Hardware name: ARM Juno development board (r1) (DT) task: ffffffc974868000 ti: ffffffc975f40000 task.ti: ffffffc975f40000 PC is at check_flags.part.35+0x17c/0x184 LR is at check_flags.part.35+0x17c/0x184 pc : [] lr : [] pstate: 600003c5 [...] ---[ end trace 74631f9305ef5020 ]--- Call trace: [] check_flags.part.35+0x17c/0x184 [] lock_acquire+0xa8/0xc4 [] breakpoint_handler+0x118/0x288 [] do_debug_exception+0x3c/0xa8 [] el1_dbg+0x18/0x6c [] do_filp_open+0x64/0xdc [] do_sys_open+0x140/0x204 [] SyS_openat+0x10/0x18 [] el0_svc_naked+0x24/0x28 possible reason: unannotated irqs-off. irq event stamp: 65857 hardirqs last enabled at (65857): [] lookup_mnt+0xf4/0x1b4 hardirqs last disabled at (65856): [] lookup_mnt+0xbc/0x1b4 softirqs last enabled at (65790): [] __do_softirq+0x1f8/0x290 softirqs last disabled at (65757): [] irq_exit+0x9c/0xd0 This patch adds the annotations to do_debug_exception(), while trying not to call trace_hardirqs_off() if el1_dbg() interrupted a task that already had irqs disabled. Signed-off-by: James Morse Signed-off-by: Will Deacon Cc: Arnd Bergmann Signed-off-by: Ben Hutchings --- arch/arm64/mm/fault.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -518,18 +518,31 @@ asmlinkage int __exception do_debug_exce { const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr); struct siginfo info; + int rv; - if (!inf->fn(addr, esr, regs)) - return 1; + /* + * Tell lockdep we disabled irqs in entry.S. Do nothing if they were + * already disabled to preserve the last enabled/disabled addresses. + */ + if (interrupts_enabled(regs)) + trace_hardirqs_off(); - pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n", - inf->name, esr, addr); + if (!inf->fn(addr, esr, regs)) { + rv = 1; + } else { + pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n", + inf->name, esr, addr); - info.si_signo = inf->sig; - info.si_errno = 0; - info.si_code = inf->code; - info.si_addr = (void __user *)addr; - arm64_notify_die("", regs, &info, 0); + info.si_signo = inf->sig; + info.si_errno = 0; + info.si_code = inf->code; + info.si_addr = (void __user *)addr; + arm64_notify_die("", regs, &info, 0); + rv = 0; + } - return 0; + if (interrupts_enabled(regs)) + trace_hardirqs_on(); + + return rv; }