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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-07-27 15:29:21 +0300
committerThierry Reding <treding@nvidia.com>2015-08-13 17:06:39 +0300
commit0b42c7c1132f331fba263f0d2ca23544770584b7 (patch)
tree70277b41ac6145870f6e4f3640bb36151eba9da7 /drivers/iommu/tegra-smmu.c
parent34d35f8cbe51bf93faf3214ee5b5d6f8ae7df4c1 (diff)
downloadlinux-0b42c7c1132f331fba263f0d2ca23544770584b7.tar.xz
iommu/tegra-smmu: Fix page table lookup in unmap/iova_to_phys methods
Fix the page table lookup in the unmap and iova_to_phys methods. Neither of these methods should allocate a page table; a missing page table should be treated the same as no mapping present. More importantly, using as_get_pte() for an IOVA corresponding with a non-present page table entry increments the use-count for the page table, on the assumption that the caller of as_get_pte() is going to setup a mapping. This is an incorrect assumption. Fix both of these bugs by providing a separate helper which only looks up the page table, but never allocates it. This is akin to pte_offset() for CPU page tables. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'drivers/iommu/tegra-smmu.c')
-rw-r--r--drivers/iommu/tegra-smmu.c43
1 files changed, 34 insertions, 9 deletions
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 4c4bc7966046..bbff5b647183 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -475,12 +475,36 @@ static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *de
}
}
+static u32 *tegra_smmu_pte_offset(struct page *pt_page, unsigned long iova)
+{
+ u32 *pt = page_address(pt_page);
+
+ return pt + iova_pt_index(iova);
+}
+
+static u32 *tegra_smmu_pte_lookup(struct tegra_smmu_as *as, unsigned long iova,
+ struct page **pagep)
+{
+ unsigned int pd_index = iova_pd_index(iova);
+ struct page *pt_page;
+ u32 *pd;
+
+ pd = page_address(as->pd);
+
+ if (!pd[pd_index])
+ return NULL;
+
+ pt_page = pfn_to_page(pd[pd_index] & as->smmu->pfn_mask);
+ *pagep = pt_page;
+
+ return tegra_smmu_pte_offset(pt_page, iova);
+}
+
static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
struct page **pagep)
{
u32 *pd = page_address(as->pd), *pt, *count;
unsigned int pde = iova_pd_index(iova);
- unsigned int pte = iova_pt_index(iova);
struct tegra_smmu *smmu = as->smmu;
struct page *page;
unsigned int i;
@@ -506,17 +530,18 @@ static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
smmu_flush(smmu);
} else {
page = pfn_to_page(pd[pde] & smmu->pfn_mask);
- pt = page_address(page);
}
*pagep = page;
+ pt = page_address(page);
+
/* Keep track of entries in this page table. */
count = page_address(as->count);
- if (pt[pte] == 0)
+ if (pt[iova_pt_index(iova)] == 0)
count[pde]++;
- return &pt[pte];
+ return tegra_smmu_pte_offset(page, iova);
}
static void tegra_smmu_pte_put_use(struct tegra_smmu_as *as, unsigned long iova)
@@ -586,14 +611,14 @@ static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
size_t size)
{
struct tegra_smmu_as *as = to_smmu_as(domain);
- struct page *page;
+ struct page *pte_page;
u32 *pte;
- pte = as_get_pte(as, iova, &page);
+ pte = tegra_smmu_pte_lookup(as, iova, &pte_page);
if (!pte || !*pte)
return 0;
- tegra_smmu_set_pte(as, iova, pte, page, 0);
+ tegra_smmu_set_pte(as, iova, pte, pte_page, 0);
tegra_smmu_pte_put_use(as, iova);
return size;
@@ -603,11 +628,11 @@ static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
dma_addr_t iova)
{
struct tegra_smmu_as *as = to_smmu_as(domain);
- struct page *page;
+ struct page *pte_page;
unsigned long pfn;
u32 *pte;
- pte = as_get_pte(as, iova, &page);
+ pte = tegra_smmu_pte_lookup(as, iova, &pte_page);
if (!pte || !*pte)
return 0;