Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966214AbbLPRIa (ORCPT ); Wed, 16 Dec 2015 12:08:30 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:34084 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966184AbbLPRI2 (ORCPT ); Wed, 16 Dec 2015 12:08:28 -0500 From: Daniel Thompson To: Russell King Cc: Daniel Thompson , Marc Zyngier , Thomas Gleixner , Jason Cooper , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, patches@linaro.org, linaro-kernel@lists.linaro.org Subject: [PATCH 2/2] irqchip/gic: Identify and report any reserved SGI IDs Date: Wed, 16 Dec 2015 17:08:06 +0000 Message-Id: <1450285686-844-3-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1450285686-844-1-git-send-email-daniel.thompson@linaro.org> References: <1450285686-844-1-git-send-email-daniel.thompson@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3293 Lines: 100 It is possible for the secure world to reserve certain SGI IDs for itself. Currently we have limited visibility of which IDs are safe to use for IPIs. Modify the GIC initialization code to actively search for reserved SGI IDs and report if any are found. Warn even more loudly if the reserved SGIs overlap with the normal IPI range. When run on an Inforce IFC6410 (Snapdragon 600) this code produces the following messages: ~~~ cut here ~~~ CPU0: Detected reserved SGI IDs: 14-15 CPU1: Detected reserved SGI IDs: 15 CPU2: Detected reserved SGI IDs: 15 CPU3: Detected reserved SGI IDs: 15 ~~~ cut here ~~~ Signed-off-by: Daniel Thompson --- drivers/irqchip/irq-gic.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index abf2ffaed392..541622da7049 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -490,6 +490,7 @@ 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; + DECLARE_BITMAP(sgi_mask, 16); /* * Setting up the CPU map is only relevant for the primary GIC @@ -511,6 +512,58 @@ static void gic_cpu_init(struct gic_chip_data *gic) for (i = 0; i < NR_GIC_CPU_IF; i++) if (i != cpu) gic_cpu_map[i] &= ~cpu_mask; + + /* + * Fiddle with the SGI set/clear registers to try identify + * any IPIs that are reserved for secure world. + */ + bitmap_fill(sgi_mask, 16); + + for (i = 0; i < 16; i++) { + void __iomem *set_reg = + dist_base + GIC_DIST_SGI_PENDING_SET + (i & ~3); + void __iomem *clear_reg = + dist_base + GIC_DIST_SGI_PENDING_CLEAR + (i & ~3); + unsigned long mask = cpu_mask << (8*(i%4)); + unsigned long flags, pending, after_clear, after_set; + + local_irq_save(flags); + + /* record original value */ + pending = readl_relaxed(set_reg); + + /* clear, test, set, and test again */ + writel_relaxed(mask, clear_reg); + after_clear = readl_relaxed(set_reg); + writel_relaxed(mask, set_reg); + after_set = readl_relaxed(set_reg); + + /* restore original value */ + writel_relaxed(mask & ~pending, clear_reg); + + local_irq_restore(flags); + + if (mask & ~after_clear && mask & after_set) + clear_bit(i, sgi_mask); + } + + /* + * Show the SGI mask if it is "interesting". Here interesting + * means that the set/clear register is implemented + * (mask is not full) and it tells us that the secure world + * has reserved some SGIs (mask is not empty). + */ + if (!bitmap_full(sgi_mask, 16) && !bitmap_empty(sgi_mask, 16)) + pr_info("CPU%d: Detected reserved SGI IDs: %*pbl\n", + cpu, 16, sgi_mask); + + /* + * Yell if the reserved IDs make the system unviable. + */ + if (!bitmap_full(sgi_mask, 16) && + find_first_bit(sgi_mask, 16) < NR_IPI) + pr_crit("CPU%d: Not enough SGI IDs; expect failure\n", + cpu); } gic_cpu_config(dist_base, NULL); -- 2.5.0 -- 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/