Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755185AbbHNOJp (ORCPT ); Fri, 14 Aug 2015 10:09:45 -0400 Received: from pandora.arm.linux.org.uk ([78.32.30.218]:59334 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428AbbHNOJn (ORCPT ); Fri, 14 Aug 2015 10:09:43 -0400 Date: Fri, 14 Aug 2015 15:09:34 +0100 From: Russell King - ARM Linux To: Murali Karicheri Cc: ssantosh@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: keystone: add a work around to handle asynchronous external abort Message-ID: <20150814140934.GX7557@n2100.arm.linux.org.uk> References: <1439320409-20084-1-git-send-email-m-karicheri2@ti.com> <55CDF579.4050408@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55CDF579.4050408@ti.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2822 Lines: 78 On Fri, Aug 14, 2015 at 10:04:41AM -0400, Murali Karicheri wrote: > On 08/11/2015 03:13 PM, Murali Karicheri wrote: > >Currently on some devices, an asynchronous external abort exception > >happens during boot up when exception handlers are enabled in kernel > >before switching to user space. This patch adds a workaround to handle > >this once during boot. Many customers are already using this > >with out any issues and is required to workaround the above issue. > > > >Signed-off-by: Murali Karicheri > >--- > > arch/arm/mach-keystone/keystone.c | 26 ++++++++++++++++++++++++++ > > 1 file changed, 26 insertions(+) > > > >diff --git a/arch/arm/mach-keystone/keystone.c b/arch/arm/mach-keystone/keystone.c > >index e2880105..c1d0fe5 100644 > >--- a/arch/arm/mach-keystone/keystone.c > >+++ b/arch/arm/mach-keystone/keystone.c > >@@ -15,6 +15,7 @@ > > #include > > #include > > #include > >+#include > > > > #include > > #include > >@@ -52,6 +53,24 @@ static struct notifier_block platform_nb = { > > .notifier_call = keystone_platform_notifier, > > }; > > > >+static bool ignore_first = true; > >+static int keystone_async_ext_abort_fault(unsigned long addr, unsigned int fsr, > >+ struct pt_regs *regs) > >+{ > >+ /* > >+ * if first time, ignore this as this is a asynchronous external abort > >+ * happening only some devices that couldn't be root caused and we add > >+ * this work around to handle this first time. > >+ */ > >+ if (ignore_first) { > >+ ignore_first = false; > >+ return 0; > >+ } > >+ > >+ /* Subsequent ones should be handled as fault */ > >+ return 1; > >+} > >+ > > static void __init keystone_init(void) > > { > > if (PHYS_OFFSET >= KEYSTONE_HIGH_PHYS_START) { > >@@ -61,6 +80,13 @@ static void __init keystone_init(void) > > } > > keystone_pm_runtime_init(); > > of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL); > >+ > >+ /* > >+ * Add a one time exception handler to catch asynchronous external > >+ * abort > >+ */ > >+ hook_fault_code(17, keystone_async_ext_abort_fault, SIGBUS, 0, > >+ "async external abort handler"); > > } > > > > static phys_addr_t keystone_virt_to_idmap(unsigned long x) > > > Can this be applied if it looks good? What causes the abort? We shouldn't be adding hacks like this to the kernel without having the full picture... -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/