From patchwork Mon Mar 21 17:14:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Morse X-Patchwork-Id: 8634531 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id A979A9F294 for ; Mon, 21 Mar 2016 17:17:32 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C1BA0202F8 for ; Mon, 21 Mar 2016 17:17:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A3B3920268 for ; Mon, 21 Mar 2016 17:17:30 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ai3Qz-0002Ek-S4; Mon, 21 Mar 2016 17:16:05 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ai3Qv-00021f-1C for linux-arm-kernel@lists.infradead.org; Mon, 21 Mar 2016 17:16:02 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 385C649; Mon, 21 Mar 2016 10:14:37 -0700 (PDT) Received: from melchizedek.cambridge.arm.com (melchizedek.cambridge.arm.com [10.1.209.158]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 556983F25F; Mon, 21 Mar 2016 10:15:40 -0700 (PDT) From: James Morse To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: mm: Add trace_irqflags annotations to do_debug_exception() Date: Mon, 21 Mar 2016 17:14:06 +0000 Message-Id: <1458580446-32474-1-git-send-email-james.morse@arm.com> X-Mailer: git-send-email 2.8.0.rc3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160321_101601_160984_4B19A192 X-CRM114-Status: GOOD ( 13.26 ) X-Spam-Score: -6.9 (------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- arch/arm64/mm/fault.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 44e56de23f79..d8b9c1da2630 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -548,20 +548,33 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, { 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; + /* + * If we came in from el0_dbg, we disabled irqs. From el1_dbg, + * we need to test pstate. + */ + if (user_mode(regs) || !(regs->pstate & PSR_I_BIT)) + 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); + rv = 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); + if (user_mode(regs) || !(regs->pstate & PSR_I_BIT)) + trace_hardirqs_on(); - return 0; + return rv; } #ifdef CONFIG_ARM64_PAN