Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754463AbbDUOuZ (ORCPT ); Tue, 21 Apr 2015 10:50:25 -0400 Received: from foss.arm.com ([217.140.101.70]:47163 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751621AbbDUOuX (ORCPT ); Tue, 21 Apr 2015 10:50:23 -0400 Date: Tue, 21 Apr 2015 15:50:14 +0100 From: Mark Rutland To: Daniel Thompson Cc: Thomas Gleixner , Jason Cooper , "linaro-kernel@lists.linaro.org" , Russell King , "patches@linaro.org" , Marc Zyngier , Stephen Boyd , Will Deacon , "linux-kernel@vger.kernel.org" , Steven Rostedt , Daniel Drake , Dmitry Pervushin , Dirk Behme , John Stultz , Tim Sander , Catalin Marinas , Sumit Semwal , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RESEND PATCH 4.0-rc7 v20 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Message-ID: <20150421145007.GB10164@leverpostej> References: <1427216014-5324-1-git-send-email-daniel.thompson@linaro.org> <1428659511-9590-1-git-send-email-daniel.thompson@linaro.org> <1428659511-9590-4-git-send-email-daniel.thompson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1428659511-9590-4-git-send-email-daniel.thompson@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3545 Lines: 83 Hi, On Fri, Apr 10, 2015 at 10:51:48AM +0100, Daniel Thompson wrote: > Currently it is not possible to exploit FIQ for systems with a GIC, even if > the systems are otherwise capable of it. This patch makes it possible > for IPIs to be delivered using FIQ. > > To do so it modifies the register state so that normal interrupts are > placed in group 1 and specific IPIs are placed into group 0. It also > configures the controller to raise group 0 interrupts using the FIQ > signal. It provides a means for architecture code to define which IPIs > shall use FIQ and to acknowledge any IPIs that are raised. > > All GIC hardware except GICv1-without-TrustZone support provides a means > to group exceptions into group 0 and group 1 but the hardware > functionality is unavailable to the kernel when a secure monitor is > present because access to the grouping registers are prohibited outside > "secure world". However when grouping is not available (or in the case > of early GICv1 implementations is very hard to configure) the code to > change groups does not deploy and all IPIs will be raised via IRQ. > > It has been tested and shown working on two systems capable of > supporting grouping (Freescale i.MX6 and STiH416). It has also been > tested for boot regressions on two systems that do not support grouping > (vexpress-a9 and Qualcomm Snapdragon 600). I just gave this a spin on my (non-MCPM) TC2, and secondaries don't come up: CPU1: failed to boot: -38 CPU2: failed to boot: -38 CPU3: failed to boot: -38 CPU4: failed to boot: -38 Brought up 1 CPUs SMP: Total of 1 processors activated (48.00 BogoMIPS). I tried investigating with a debugger. The unbooted CPUs look to be stuck at the FW's spin loop, but the text doesn't look right (I see a load of ADDEQ r0, r0, r0, #LSL 1 where there was previously a WFI loop). That could be a bug with my debugger though. If I pause the CPUs at the right point, they sometimes enter the kernel successfully. I don't have a good explanation for that. [...] > @@ -427,6 +535,7 @@ static void gic_cpu_init(struct gic_chip_data *gic) > void __iomem *base = gic_data_cpu_base(gic); > unsigned int cpu_mask, cpu = smp_processor_id(); > int i; > + unsigned long secure_irqs, secure_irq; I think secure_irq(s) is a misnomer here. It's just a mask of FIQ bits. > > /* > * Get what the GIC says our CPU mask is. > @@ -445,6 +554,20 @@ static void gic_cpu_init(struct gic_chip_data *gic) > > gic_cpu_config(dist_base, NULL); > > + /* > + * If the distributor is configured to support interrupt grouping > + * then set any PPI and SGI interrupts not set in SMP_IPI_FIQ_MASK > + * to be group1 and ensure any remaining group 0 interrupts have > + * the right priority. > + */ > + if (GICD_ENABLE_GRP1 & readl_relaxed(dist_base + GIC_DIST_CTRL)) { > + secure_irqs = SMP_IPI_FIQ_MASK; > + writel_relaxed(~secure_irqs, dist_base + GIC_DIST_IGROUP + 0); > + gic->igroup0_shadow = ~secure_irqs; > + for_each_set_bit(secure_irq, &secure_irqs, 16) > + gic_set_group_irq(gic, secure_irq, 0); > + } This only pokes GICD registers. Why isn't this in gic_dist_init? Mark. -- 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/