[{"id":1761780,"web_url":"http://patchwork.ozlabs.org/comment/1761780/","msgid":"<076df89b-1fb1-bf15-3f81-2ac7a4169b18@synopsys.com>","list_archive_url":null,"date":"2017-09-01T16:01:54","subject":"Re: [PATCH v2] arc: Re-enable MMU upon die()","submitter":{"id":68387,"url":"http://patchwork.ozlabs.org/api/people/68387/","name":"Jose Abreu","email":"Jose.Abreu@synopsys.com"},"content":"Oops, the commit title is now a little bit odd. Let me rephrase\nand send a new version.\n\nOn 01-09-2017 17:00, Jose Abreu wrote:\n> I recently came upon a scenario where I would get a double fault\n> after a machine check error. It turns out that for Ksymbol lookup\n> to work with modules we need to have MMU enabled because module\n> address is mapped in the cached space.\n>\n> This patch re-enables the MMU before start printing the stacktrace\n> making stacktracing of modules work upon a fatal exception.\n>\n> Signed-off-by: Jose Abreu \n> Cc: Vineet Gupta \n> Cc: Alexey Brodkin \n>\n> Changes from v1:\n> \t- Moved MMU re-enable to machine check exception handler\n> ---\n> arch/arc/kernel/traps.c | 5 +++++\n> 1 file changed, 5 insertions(+)\n>\n> diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c\n> index ff83e78..d92f161 100644\n> --- a/arch/arc/kernel/traps.c\n> +++ b/arch/arc/kernel/traps.c\n> @@ -19,6 +19,8 @@\n> #include \n> #include \n> #include \n> +#include \n> +#include \n> #include \n> #include \n> #include \n> @@ -103,6 +105,9 @@ int do_misaligned_access(unsigned long address, struct pt_regs *regs,\n> */\n> void do_machine_check_fault(unsigned long address, struct pt_regs *regs)\n> {\n> +\t/* MMU must be enabled for Ksymbol lookup in modules */\n> +\twrite_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));\n> +\n> \tdie(\"Machine Check Exception\", regs, address);\n> }\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org; spf=none (mailfrom)\n\tsmtp.mailfrom=lists.infradead.org (client-ip=65.50.211.133;\n\thelo=bombadil.infradead.org;\n\tenvelope-from=linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org;\n\treceiver=)","ozlabs.org; dkim=pass (2048-bit key;\n\tunprotected) header.d=lists.infradead.org\n\theader.i=@lists.infradead.org header.b=\"V1qtd5IF\"; \n\tdkim-atps=neutral"],"Received":["from bombadil.infradead.org (bombadil.infradead.org\n\t[65.50.211.133])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256\n\tbits)) (No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xkPC50KWMz9s2G\n\tfor ;\n\tSat, 2 Sep 2017 02:02:25 +1000 (AEST)","from localhost ([127.0.0.1] helo=bombadil.infradead.org)\n\tby bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux))\n\tid 1dnoOl-0006ud-MC; Fri, 01 Sep 2017 16:02:23 +0000","from us01smtprelay-2.synopsys.com ([198.182.47.9]\n\thelo=smtprelay.synopsys.com)\n\tby bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux))\n\tid 1dnoOi-0006sX-6w for linux-snps-arc@lists.infradead.org;\n\tFri, 01 Sep 2017 16:02:22 +0000","from mailhost.synopsys.com (mailhost1.synopsys.com [10.12.238.239])\n\tby smtprelay.synopsys.com (Postfix) with ESMTP id 1B31A24E1EDB\n\tfor ;\n\tFri, 1 Sep 2017 09:02:00 -0700 (PDT)","from mailhost.synopsys.com (localhost [127.0.0.1])\n\tby mailhost.synopsys.com (Postfix) with ESMTP id 01A98A07\n\tfor ;\n\tFri, 1 Sep 2017 09:02:00 -0700 (PDT)","from us01wehtc1.internal.synopsys.com\n\t(us01wehtc1-vip.internal.synopsys.com [10.12.239.236])\n\tby mailhost.synopsys.com (Postfix) with ESMTP id EB3D4A04\n\tfor ;\n\tFri, 1 Sep 2017 09:01:59 -0700 (PDT)","from DE02WEHTCA.internal.synopsys.com (10.225.19.92) by\n\tus01wehtc1.internal.synopsys.com (10.12.239.231) with Microsoft SMTP\n\tServer (TLS) id 14.3.266.1; Fri, 1 Sep 2017 09:01:59 -0700","from DE02WEHTCB.internal.synopsys.com (10.225.19.94) by\n\tDE02WEHTCA.internal.synopsys.com (10.225.19.92) with Microsoft SMTP\n\tServer (TLS) id 14.3.266.1; Fri, 1 Sep 2017 18:01:57 +0200","from [10.0.2.15] (10.107.19.75) by DE02WEHTCB.internal.synopsys.com\n\t(10.225.19.80) with Microsoft SMTP Server (TLS) id 14.3.266.1;\n\tFri, 1 Sep 2017 18:01:57 +0200"],"DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;\n\td=lists.infradead.org; s=bombadil.20170209; h=Sender:\n\tContent-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post:\n\tList-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:\n\tMessage-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description\n\t:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:\n\tList-Owner; bh=/HT9CUmbzlkK+1vB+yn+qzgffYaVPLlOLUZMi0eT5f4=;\n\tb=V1qtd5IFmeX2RA\n\tUt9inEI5O4DxQBxXRvW1XQ2MIbMEqAoj/M2GxMyGa858G1nk9c3RucFOZZNnal+xrmh6tt2g/7hZ5\n\trjfqT8lP8vZ0YBHnBvICqRQaVh32dMXvLXPJzDfcuinOrKgtd1CW0ffJOf2/xaRyCORqQvHzaXklW\n\tovKwZkdQ+G4aYFjVcQ+047MEyMLywApxaj0KDCPPIYz6xV2DC9jb6dND4jLZvrCYHwm52qL7OOmNs\n\tKRbRgu8wn4rXZktdoLOfndgLZphF3bbi0OIDenp+X7/XwFA9emBx2wIJks2Rnirv4bRcRn10so/wz\n\t8vC668zDKbNa5VDrwgLQ==;","Subject":"Re: [PATCH v2] arc: Re-enable MMU upon die()","To":"","References":"<12fbfb3099623ae8044f48983bfa58321495cf79.1504281470.git.joabreu@synopsys.com>","From":"Jose Abreu ","Message-ID":"<076df89b-1fb1-bf15-3f81-2ac7a4169b18@synopsys.com>","Date":"Fri, 1 Sep 2017 17:01:54 +0100","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101\n\tThunderbird/45.4.0","MIME-Version":"1.0","In-Reply-To":"<12fbfb3099623ae8044f48983bfa58321495cf79.1504281470.git.joabreu@synopsys.com>","X-Originating-IP":"[10.107.19.75]","X-CRM114-Version":"20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 ","X-CRM114-CacheID":"sfid-20170901_090220_263503_AD29AD9A ","X-CRM114-Status":"GOOD ( 10.52 )","X-Spam-Score":"-1.9 (-)","X-Spam-Report":"SpamAssassin version 3.4.1 on bombadil.infradead.org summary:\n\tContent analysis details: (-1.9 points)\n\tpts rule name description\n\t---- ----------------------\n\t--------------------------------------------------\n\t-0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/,\n\tno trust [198.182.47.9 listed in list.dnswl.org]\n\t-0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay\n\tdomain\n\t-1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1%\n\t[score: 0.0000]","X-BeenThere":"linux-snps-arc@lists.infradead.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"Linux on Synopsys ARC Processors\n\t","List-Unsubscribe":", \n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":", \n\t","Cc":"Vineet Gupta ,\n\tAlexey Brodkin ","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Transfer-Encoding":"7bit","Sender":"\"linux-snps-arc\" ","Errors-To":"linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org"}},{"id":1761784,"web_url":"http://patchwork.ozlabs.org/comment/1761784/","msgid":"<9dc23712-b8ea-9f4e-d2c1-a8149157af16@synopsys.com>","list_archive_url":null,"date":"2017-09-01T16:05:51","subject":"Re: [PATCH v2] arc: Re-enable MMU upon die()","submitter":{"id":26707,"url":"http://patchwork.ozlabs.org/api/people/26707/","name":"Vineet Gupta","email":"Vineet.Gupta1@synopsys.com"},"content":"On 09/01/2017 09:01 AM, Jose Abreu wrote:\n> Oops, the commit title is now a little bit odd. Let me rephrase\n> and send a new version.\n\nDon't worry - I'll fix it up here !\n\nThx,\n-Vineet\n\n>\n> On 01-09-2017 17:00, Jose Abreu wrote:\n>> I recently came upon a scenario where I would get a double fault\n>> after a machine check error. It turns out that for Ksymbol lookup\n>> to work with modules we need to have MMU enabled because module\n>> address is mapped in the cached space.\n>>\n>> This patch re-enables the MMU before start printing the stacktrace\n>> making stacktracing of modules work upon a fatal exception.\n>>\n>> Signed-off-by: Jose Abreu \n>> Cc: Vineet Gupta \n>> Cc: Alexey Brodkin \n>>\n>> Changes from v1:\n>> \t- Moved MMU re-enable to machine check exception handler\n>> ---\n>> arch/arc/kernel/traps.c | 5 +++++\n>> 1 file changed, 5 insertions(+)\n>>\n>> diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c\n>> index ff83e78..d92f161 100644\n>> --- a/arch/arc/kernel/traps.c\n>> +++ b/arch/arc/kernel/traps.c\n>> @@ -19,6 +19,8 @@\n>> #include \n>> #include \n>> #include \n>> +#include \n>> +#include \n>> #include \n>> #include \n>> #include \n>> @@ -103,6 +105,9 @@ int do_misaligned_access(unsigned long address, struct pt_regs *regs,\n>> */\n>> void do_machine_check_fault(unsigned long address, struct pt_regs *regs)\n>> {\n>> +\t/* MMU must be enabled for Ksymbol lookup in modules */\n>> +\twrite_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));\n>> +\n>> \tdie(\"Machine Check Exception\", regs, address);\n>> }\n>> \n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org; 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