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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 916A2C433DF for ; Fri, 19 Jun 2020 15:17:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7226D2080C for ; Fri, 19 Jun 2020 15:17:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579868; bh=PG0qiH2KEanMcWHB5FHf6WHtqvnKB05Xm9dmC6kGVQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LN3BDNukQusmjoYdk/Q9MYLv58NTxpIw0QoYq2r92cyS7JkUCdL18SOXDoPsYER0B vdWPNFRTbPz/eg3iSev9mqQ0s7FI7wvXIks7B7gmLC/Hc2TjzjS5J6GYfYRmB9CXbY L2KjQ03Vtfm6y4T3CaJsi7E6QI5MkvKB16y4CmjA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392545AbgFSPRs (ORCPT ); Fri, 19 Jun 2020 11:17:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:48202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389741AbgFSPRg (ORCPT ); Fri, 19 Jun 2020 11:17:36 -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 59B8421919; Fri, 19 Jun 2020 15:17:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579855; bh=PG0qiH2KEanMcWHB5FHf6WHtqvnKB05Xm9dmC6kGVQA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AXXYJaFjwV5ruqG0DCO55eo9DcwyQlh1jwf32Khaspace2eEVsy1wLaqWCRcXcint OPluPdoE8v1SJgrJBRqCETYPLF/BjM1hoR2YdKfhX2+Jbqvgu8dcpBScoTcdECU+9W qvLRPQ14opHliX+fZboWygDVZNjfluMEHJaCxrmo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Thompson , Douglas Anderson , Will Deacon , Sasha Levin Subject: [PATCH 5.7 030/376] arm64: cacheflush: Fix KGDB trap detection Date: Fri, 19 Jun 2020 16:29:08 +0200 Message-Id: <20200619141711.780398678@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141710.350494719@linuxfoundation.org> References: <20200619141710.350494719@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Thompson [ Upstream commit ab8ad279ceac4fc78ae4dcf1a26326e05695e537 ] flush_icache_range() contains a bodge to avoid issuing IPIs when the kgdb trap handler is running because issuing IPIs is unsafe (and not needed) in this execution context. However the current test, based on kgdb_connected is flawed: it both over-matches and under-matches. The over match occurs because kgdb_connected is set when gdb attaches to the stub and remains set during normal running. This is relatively harmelss because in almost all cases irq_disabled() will be false. The under match is more serious. When kdb is used instead of kgdb to access the debugger then kgdb_connected is not set in all the places that the debug core updates sw breakpoints (and hence flushes the icache). This can lead to deadlock. Fix by replacing the ad-hoc check with the proper kgdb macro. This also allows us to drop the #ifdef wrapper. Fixes: 3b8c9f1cdfc5 ("arm64: IPI each CPU after invalidating the I-cache for kernel mappings") Signed-off-by: Daniel Thompson Reviewed-by: Douglas Anderson Link: https://lore.kernel.org/r/20200504170518.2959478-1-daniel.thompson@linaro.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/include/asm/cacheflush.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h index e6cca3d4acf7..ce50c1f1f1ea 100644 --- a/arch/arm64/include/asm/cacheflush.h +++ b/arch/arm64/include/asm/cacheflush.h @@ -79,7 +79,7 @@ static inline void flush_icache_range(unsigned long start, unsigned long end) * IPI all online CPUs so that they undergo a context synchronization * event and are forced to refetch the new instructions. */ -#ifdef CONFIG_KGDB + /* * KGDB performs cache maintenance with interrupts disabled, so we * will deadlock trying to IPI the secondary CPUs. In theory, we can @@ -89,9 +89,9 @@ static inline void flush_icache_range(unsigned long start, unsigned long end) * the patching operation, so we don't need extra IPIs here anyway. * In which case, add a KGDB-specific bodge and return early. */ - if (kgdb_connected && irqs_disabled()) + if (in_dbg_master()) return; -#endif + kick_all_cpus_sync(); } -- 2.25.1