From patchwork Fri Jun 19 14:32:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 191210 Delivered-To: patch@linaro.org Received: by 2002:a92:cf06:0:0:0:0:0 with SMTP id c6csp596996ilo; Fri, 19 Jun 2020 07:49:51 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw+Ckf9Be5JDKDan1kHxaN5pDbMqOBqq9x8i3ktc9d4t04BA7ManFuctjaBHGMVvxQlftEp X-Received: by 2002:a17:907:402e:: with SMTP id nr22mr3837873ejb.239.1592578191185; Fri, 19 Jun 2020 07:49:51 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1592578191; cv=none; d=google.com; s=arc-20160816; b=x9qDHcfeR2mHHEotROnkZGlsZwiUwPk2PGJ1VTRp2agY9Ly74U/CPj8LMfRvuVTjuk caXQ71zEDUvttyHmJVtmNuOGkUU9A4sUdnTNkw/YHimR4LXCSxhOD9JaMuqOTzRNO5nP H82GvgYAx0ZpDVg3yLsnH/0nW36o4lnuFedrSyd2ABT9USo7PeJi1u77qjJbH7d9mNrg FEgE/kEjooaK6aFW75I+xawF0nncgeKeRgUoV3x4AGy8BsIzoc9TXivhnyxA8eH/1545 4rXuDvBMRusOAGHfN/BXnBZp2KpXeFncRgaeWaIXUX7AFcCyte5Lgebu5FCyy7COU8Tp 3LEQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=YZzxlBFe2O2LHiexT9ac/y3DZO0Y8oTx+57qzeMEvXE=; b=INxopizNQYNwNTYpaY+SEap4HvYLAosgSObLqkoZfYOMFVXGm5urx8UcMjhTJdI31U HJ+Sn7/3s0JXr/UtRjC1sMrwhvPguEKuvxG7qoqBPKvy1UewdqoY5Hv7e6QnGLvGR4hX moUowE4HgA3SCxiY//LQ4leow8/7GdEQIjPgZvc0xzhZE8mFvXnTPArI5UqEZJsw0hO6 x74SZeBnH7vREDZMJn1/bNV/91kct42GpfBUF3/k3/nke9Gg7XzFaKLMYDxiRLtg1kAa o4tSK5Fg0YH+ExzHoDwcKmJILCl/afRodqIZdxByhEW634LVw78jl6P0IlM0jWOEWHKf ikvw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="ii4/PIoP"; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ce13si3836797edb.81.2020.06.19.07.49.51; Fri, 19 Jun 2020 07:49:51 -0700 (PDT) Received-SPF: pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="ii4/PIoP"; spf=pass (google.com: domain of stable-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389251AbgFSOtt (ORCPT + 15 others); Fri, 19 Jun 2020 10:49:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:42482 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389246AbgFSOtr (ORCPT ); Fri, 19 Jun 2020 10:49:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 D67BB217D8; Fri, 19 Jun 2020 14:49:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592578187; bh=Uw9/vRLVgKmqGjw40c38O9e7lpuxn5NHt5DzieU+7Dk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ii4/PIoPrdf+SvdK+tKTMgvJ1kt9sgZ6pLc5LY9ylw0vLCH6RqCo51VaZjFqS7MDf paUcemSvQc3OxVqJJ+PCZPglnePtA+CaemenwHWo2SY/fYuv7TJf3mdC+tJFEv8rXR 0G9U2XclBeoi2hkHrSF94B/neVS95KBVS3mLSGC4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Will Deacon , Douglas Anderson , Daniel Thompson , Sasha Levin Subject: [PATCH 4.14 116/190] kgdb: Fix spurious true from in_dbg_master() Date: Fri, 19 Jun 2020 16:32:41 +0200 Message-Id: <20200619141639.431837006@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141633.446429600@linuxfoundation.org> References: <20200619141633.446429600@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Thompson [ Upstream commit 3fec4aecb311995189217e64d725cfe84a568de3 ] Currently there is a small window where a badly timed migration could cause in_dbg_master() to spuriously return true. Specifically if we migrate to a new core after reading the processor id and the previous core takes a breakpoint then we will evaluate true if we read kgdb_active before we get the IPI to bring us to halt. Fix this by checking irqs_disabled() first. Interrupts are always disabled when we are executing the kgdb trap so this is an acceptable prerequisite. This also allows us to replace raw_smp_processor_id() with smp_processor_id() since the short circuit logic will prevent warnings from PREEMPT_DEBUG. Fixes: dcc7871128e9 ("kgdb: core changes to support kdb") Suggested-by: Will Deacon Link: https://lore.kernel.org/r/20200506164223.2875760-1-daniel.thompson@linaro.org Reviewed-by: Douglas Anderson Signed-off-by: Daniel Thompson Signed-off-by: Sasha Levin --- include/linux/kgdb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.25.1 diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index e465bb15912d..6be5545d3584 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -317,7 +317,7 @@ extern void gdbstub_exit(int status); extern int kgdb_single_step; extern atomic_t kgdb_active; #define in_dbg_master() \ - (raw_smp_processor_id() == atomic_read(&kgdb_active)) + (irqs_disabled() && (smp_processor_id() == atomic_read(&kgdb_active))) extern bool dbg_is_early; extern void __init dbg_late_init(void); #else /* ! CONFIG_KGDB */