From patchwork Thu Jul 11 22:48:51 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Warren X-Patchwork-Id: 2826682 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D316DC0AB2 for ; Thu, 11 Jul 2013 22:49:32 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E458A200E0 for ; Thu, 11 Jul 2013 22:49:31 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D4594200DF for ; Thu, 11 Jul 2013 22:49:30 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UxPfy-0003mq-Ri; Thu, 11 Jul 2013 22:49:27 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UxPfv-0003aF-J4; Thu, 11 Jul 2013 22:49:23 +0000 Received: from avon.wwwdotorg.org ([2001:470:1f0f:bd7::2]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UxPfr-0003ZA-Q2; Thu, 11 Jul 2013 22:49:20 +0000 Received: from severn.wwwdotorg.org (unknown [192.168.65.5]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by avon.wwwdotorg.org (Postfix) with ESMTPS id 98C7863C3; Thu, 11 Jul 2013 17:00:42 -0600 (MDT) Received: from swarren-lx1.nvidia.com (localhost [127.0.0.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by severn.wwwdotorg.org (Postfix) with ESMTPSA id DE06FE461B; Thu, 11 Jul 2013 16:48:55 -0600 (MDT) From: Stephen Warren To: Russell King Subject: [PATCH] ARM: kexec: validate CPU hotplug support Date: Thu, 11 Jul 2013 16:48:51 -0600 Message-Id: <1373582931-11956-1-git-send-email-swarren@wwwdotorg.org> X-Mailer: git-send-email 1.8.1.5 X-NVConfidentiality: public X-Virus-Scanned: clamav-milter 0.97.7 at avon.wwwdotorg.org X-Virus-Status: Clean X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130711_184919_956907_03BD2466 X-CRM114-Status: GOOD ( 15.56 ) X-Spam-Score: -2.2 (--) Cc: Stephen Warren , kexec@lists.infradead.org, Will Deacon , linux-kernel@vger.kernel.org, Simon Horman , ebiederm@xmission.com, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Stephen Warren Architectures should fully validate whether kexec is possible as part of machine_kexec_prepare(), so that user-space's kexec_load() operation can report any problems. Performing validation in machine_kexec() itself is too late, since it is not allowed to return. Prior to this patch, ARM's machine_kexec() was testing after-the-fact whether machine_kexec_prepare() was able to disable all but one CPU. Instead, modify machine_kexec_prepare() to validate all conditions necessary for machine_kexec_prepare()'s to succeed. BUG if the validation succeeded, yet disabling the CPUs didn't actually work. Signed-off-by: Stephen Warren Acked-by: "Eric W. Biederman" --- Russell, does it make sense for this to be cc: stable as a follow-up to 19ab428 "ARM: 7759/1: decouple CPU offlining from reboot/shutdown"? arch/arm/include/asm/smp_plat.h | 3 +++ arch/arm/kernel/machine_kexec.c | 20 ++++++++++++++++---- arch/arm/kernel/smp.c | 8 ++++++++ 3 files changed, 27 insertions(+), 4 deletions(-) diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h index 6462a72..a252c0b 100644 --- a/arch/arm/include/asm/smp_plat.h +++ b/arch/arm/include/asm/smp_plat.h @@ -88,4 +88,7 @@ static inline u32 mpidr_hash_size(void) { return 1 << mpidr_hash.bits; } + +extern int platform_can_cpu_hotplug(void); + #endif diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 4fb074c..d7c82df 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -15,6 +15,7 @@ #include #include #include +#include #include extern const unsigned char relocate_new_kernel[]; @@ -39,6 +40,14 @@ int machine_kexec_prepare(struct kimage *image) int i, err; /* + * Validate that if the current HW supports SMP, then the SW supports + * and implements CPU hotplug for the current HW. If not, we won't be + * able to kexec reliably, so fail the prepare operation. + */ + if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug()) + return -EINVAL; + + /* * No segment at default ATAGs address. try to locate * a dtb using magic. */ @@ -134,10 +143,13 @@ void machine_kexec(struct kimage *image) unsigned long reboot_code_buffer_phys; void *reboot_code_buffer; - if (num_online_cpus() > 1) { - pr_err("kexec: error: multiple CPUs still online\n"); - return; - } + /* + * This can only happen if machine_shutdown() failed to disable some + * CPU, and that can only happen if the checks in + * machine_kexec_prepare() were not correct. If this fails, we can't + * reliably kexec anyway, so BUG_ON is appropriate. + */ + BUG_ON(num_online_cpus() > 1); page_list = image->head & PAGE_MASK; diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index c2b4f8f..5b9e501 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -145,6 +145,14 @@ int boot_secondary(unsigned int cpu, struct task_struct *idle) return -ENOSYS; } +int platform_can_cpu_hotplug(void) +{ + if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) || !smp_ops.cpu_kill) + return 0; + + return 1; +} + #ifdef CONFIG_HOTPLUG_CPU static void percpu_timer_stop(void);