From mboxrd@z Thu Jan 1 00:00:00 1970 From: andreas.herrmann@calxeda.com (Andreas Herrmann) Date: Tue, 24 Sep 2013 17:06:58 +0200 Subject: [PATCH 4/7] iommu/arm-smmu: Check for num_context_irqs > 0 to avoid divide by zero exception In-Reply-To: <1380035221-11576-1-git-send-email-andreas.herrmann@calxeda.com> References: <1380035221-11576-1-git-send-email-andreas.herrmann@calxeda.com> Message-ID: <1380035221-11576-5-git-send-email-andreas.herrmann@calxeda.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org With the right (or wrong;-) definition of v1 SMMU node in DTB it is possible to trigger a division by zero in arm_smmu_init_domain_context (if number of context irqs is 0): if (smmu->version == 1) { root_cfg->irptndx = atomic_inc_return(&smmu->irptndx); ? root_cfg->irptndx %= smmu->num_context_irqs; } else { Avoid this by checking for num_context_irqs > 0 before trying to assign interrupts to contexts. Signed-off-by: Andreas Herrmann --- drivers/iommu/arm-smmu.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index f5a856e..0dfd255 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -828,21 +828,24 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain, return ret; root_cfg->cbndx = ret; - if (smmu->version == 1) { - root_cfg->irptndx = atomic_inc_return(&smmu->irptndx); - root_cfg->irptndx %= smmu->num_context_irqs; - } else { - root_cfg->irptndx = root_cfg->cbndx; - } - irq = smmu->irqs[smmu->num_global_irqs + root_cfg->irptndx]; - ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED, - "arm-smmu-context-fault", domain); - if (IS_ERR_VALUE(ret)) { - dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n", - root_cfg->irptndx, irq); - root_cfg->irptndx = -1; - goto out_free_context; + if (smmu->num_context_irqs) { + if (smmu->version == 1) { + root_cfg->irptndx = atomic_inc_return(&smmu->irptndx); + root_cfg->irptndx %= smmu->num_context_irqs; + } else { + root_cfg->irptndx = root_cfg->cbndx; + } + + irq = smmu->irqs[smmu->num_global_irqs + root_cfg->irptndx]; + ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED, + "arm-smmu-context-fault", domain); + if (IS_ERR_VALUE(ret)) { + dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n", + root_cfg->irptndx, irq); + root_cfg->irptndx = -1; + goto out_free_context; + } } root_cfg->smmu = smmu; -- 1.7.9.5