From patchwork Fri Jun 19 14:32:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 191254 Delivered-To: patch@linaro.org Received: by 2002:a92:cf06:0:0:0:0:0 with SMTP id c6csp678140ilo; Fri, 19 Jun 2020 09:23:24 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwsPwwDAjQ1xd1edB0H8IInVwo6RLR1Owf+JF+BLpWxwwFqn6qpEb/2rlTywswCzZCzzbF1 X-Received: by 2002:a17:906:1d1a:: with SMTP id n26mr4217428ejh.351.1592583804314; Fri, 19 Jun 2020 09:23:24 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1592583804; cv=none; d=google.com; s=arc-20160816; b=GX8u+UqTt3m8RCdRca+SZCKIxTdnI1nbjReP16fIEMZSlDDMG4UIEkETQJtLBQFebq QTjrXkYi/CQEYzjltH6fDYR0nudt9XxVpRa9pBZK650duFDOAhC0NY80BxatsQ/9BQXd qM93J072999FtxP7dwUw2kksx1lA3yK4qTHX9AoP2olWbTf44do3HI+RZVUfyWoJeGc/ rXYg+iUMfsqPN/aYYrhkgWM1WzNMKoz5Rn7ZiXsPEUGoO1vzWLbSALveMy8Neaezi4v/ jayZ5PNwJkYhC6mjZWTk046k04ugMmxW2RTe3aQknfzSQKI68MkycjfokOm1mDolXEgH WB7g== 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=w5UV97yqE3Ld2gjDURRm4BMoQAWFoVks3MyiSy5e3XJovYWLzDIObutZZmr90v7RE2 e2Ff9ii3SsIiTdU+FXYJqE5fjRqOfMQH+dlXGUs0hF9V30aGFWs1qlVTuACZe7AhI2Tr R38nZ4PO6b5CrYUVDC40pwX8AapZ8Mr/FGTdr1cSYb3ODuV2Fpqa+FED/3gBNS5Dqlo5 KbxqUUAm6dI6G3Fy/En8IQVuycF5Pg3j1zmIxe3PE0aggVmrrKHn48HFvmHZWNzjQMqY zR69qNv28BhW5Ehg0a+L3vl7JI3HAqzpwtTMIyybqTcAmCCD1g0Bqr9AFBZNGPtZUAz3 0X3w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=chROSi0M; 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 d16si4086985edx.546.2020.06.19.09.23.24; Fri, 19 Jun 2020 09:23:24 -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=chROSi0M; 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 S2390515AbgFSO7Y (ORCPT + 15 others); Fri, 19 Jun 2020 10:59:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:55496 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388231AbgFSO7W (ORCPT ); Fri, 19 Jun 2020 10:59:22 -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 7B67921924; Fri, 19 Jun 2020 14:59:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592578761; bh=Uw9/vRLVgKmqGjw40c38O9e7lpuxn5NHt5DzieU+7Dk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=chROSi0MVC+D1fvcMQkZoNawkPlm8D1bUeErELZhzCzJTgPSLWRQiPNIepB1mBDak jJ5/LR+BZuSkPaUcyQiPlF02Gyeq9HlDjXXjZjjO0K4jl2x7o5wTf725YcKg9z3OUj /WsgMaXuPt63Dtemr5aqI1XhKONhZnA4c+uF7RFI= 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 4.19 146/267] kgdb: Fix spurious true from in_dbg_master() Date: Fri, 19 Jun 2020 16:32:11 +0200 Message-Id: <20200619141655.826958966@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141648.840376470@linuxfoundation.org> References: <20200619141648.840376470@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 */