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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>
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parent
34d35f8cbe
commit
0b42c7c113
1 changed files with 34 additions and 9 deletions
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@ -475,12 +475,36 @@ static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *de
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}
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}
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static u32 *tegra_smmu_pte_offset(struct page *pt_page, unsigned long iova)
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{
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u32 *pt = page_address(pt_page);
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return pt + iova_pt_index(iova);
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}
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static u32 *tegra_smmu_pte_lookup(struct tegra_smmu_as *as, unsigned long iova,
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struct page **pagep)
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{
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unsigned int pd_index = iova_pd_index(iova);
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struct page *pt_page;
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u32 *pd;
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pd = page_address(as->pd);
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if (!pd[pd_index])
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return NULL;
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pt_page = pfn_to_page(pd[pd_index] & as->smmu->pfn_mask);
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*pagep = pt_page;
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return tegra_smmu_pte_offset(pt_page, iova);
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}
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static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
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struct page **pagep)
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{
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u32 *pd = page_address(as->pd), *pt, *count;
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unsigned int pde = iova_pd_index(iova);
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unsigned int pte = iova_pt_index(iova);
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struct tegra_smmu *smmu = as->smmu;
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struct page *page;
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unsigned int i;
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@ -506,17 +530,18 @@ static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
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smmu_flush(smmu);
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} else {
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page = pfn_to_page(pd[pde] & smmu->pfn_mask);
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pt = page_address(page);
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}
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*pagep = page;
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pt = page_address(page);
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/* Keep track of entries in this page table. */
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count = page_address(as->count);
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if (pt[pte] == 0)
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if (pt[iova_pt_index(iova)] == 0)
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count[pde]++;
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return &pt[pte];
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return tegra_smmu_pte_offset(page, iova);
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}
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static void tegra_smmu_pte_put_use(struct tegra_smmu_as *as, unsigned long iova)
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@ -586,14 +611,14 @@ static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
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size_t size)
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{
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struct tegra_smmu_as *as = to_smmu_as(domain);
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struct page *page;
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struct page *pte_page;
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u32 *pte;
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pte = as_get_pte(as, iova, &page);
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pte = tegra_smmu_pte_lookup(as, iova, &pte_page);
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if (!pte || !*pte)
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return 0;
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tegra_smmu_set_pte(as, iova, pte, page, 0);
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tegra_smmu_set_pte(as, iova, pte, pte_page, 0);
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tegra_smmu_pte_put_use(as, iova);
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return size;
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@ -603,11 +628,11 @@ static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
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dma_addr_t iova)
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{
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struct tegra_smmu_as *as = to_smmu_as(domain);
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struct page *page;
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struct page *pte_page;
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unsigned long pfn;
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u32 *pte;
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pte = as_get_pte(as, iova, &page);
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pte = tegra_smmu_pte_lookup(as, iova, &pte_page);
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if (!pte || !*pte)
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return 0;
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