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Commit 40c9b882 authored by Dmitry Osipenko's avatar Dmitry Osipenko Committed by Joerg Roedel
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iommu/tegra: gart: Add debugging facility 



Page mapping could overwritten by an accident (a bug). We can catch this
case by checking 'VALID' bit of GART's page entry prior to mapping of a
page. Since that check introduces a small performance impact, it should be
enabled explicitly using new GART's kernel module 'debug' parameter.

Signed-off-by: default avatarDmitry Osipenko <digetx@gmail.com>
Acked-by: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 6da6c0db

drivers/iommu/tegra-gart.c

+13 −0
Original line number Diff line number Diff line
@@ -72,6 +72,8 @@ struct gart_domain { 


static struct gart_device *gart_handle; /* unique for a system */



static bool gart_debug;



#define GART_PTE(_pfn)						\

	(GART_ENTRY_PHYS_ADDR_VALID | ((_pfn) << PAGE_SHIFT))
@@ -271,6 +273,7 @@ static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova, 
	struct gart_device *gart = gart_domain->gart;

	unsigned long flags;

	unsigned long pfn;

	unsigned long pte;



	if (!gart_iova_range_valid(gart, iova, bytes))

		return -EINVAL;
@@ -282,6 +285,14 @@ static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova, 
		spin_unlock_irqrestore(&gart->pte_lock, flags);

		return -EINVAL;

	}

	if (gart_debug) {

		pte = gart_read_pte(gart, iova);

		if (pte & GART_ENTRY_PHYS_ADDR_VALID) {

			spin_unlock_irqrestore(&gart->pte_lock, flags);

			dev_err(gart->dev, "Page entry is in-use\n");

			return -EBUSY;

		}

	}

	gart_set_pte(gart, iova, GART_PTE(pfn));

	FLUSH_GART_REGS(gart);

	spin_unlock_irqrestore(&gart->pte_lock, flags);
@@ -515,7 +526,9 @@ static void __exit tegra_gart_exit(void) 


subsys_initcall(tegra_gart_init);

module_exit(tegra_gart_exit);

module_param(gart_debug, bool, 0644);



MODULE_PARM_DESC(gart_debug, "Enable GART debugging");

MODULE_DESCRIPTION("IOMMU API for GART in Tegra20");

MODULE_AUTHOR("Hiroshi DOYU <hdoyu@nvidia.com>");

MODULE_ALIAS("platform:tegra-gart");