From 1e9d90dbed120ec98517428ffff4dacd9797e39d Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Tue, 1 Sep 2020 15:16:45 -0700 Subject: dma-mapping: introduce dma_get_seg_boundary_nr_pages() We found that callers of dma_get_seg_boundary mostly do an ALIGN with page mask and then do a page shift to get number of pages: ALIGN(boundary + 1, 1 << shift) >> shift However, the boundary might be as large as ULONG_MAX, which means that a device has no specific boundary limit. So either "+ 1" or passing it to ALIGN() would potentially overflow. According to kernel defines: #define ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) #define ALIGN(x, a) ALIGN_MASK(x, (typeof(x))(a) - 1) We can simplify the logic here into a helper function doing: ALIGN(boundary + 1, 1 << shift) >> shift = ALIGN_MASK(b + 1, (1 << s) - 1) >> s = {[b + 1 + (1 << s) - 1] & ~[(1 << s) - 1]} >> s = [b + 1 + (1 << s) - 1] >> s = [b + (1 << s)] >> s = (b >> s) + 1 This patch introduces and applies dma_get_seg_boundary_nr_pages() as an overflow-free helper for the dma_get_seg_boundary() callers to get numbers of pages. It also takes care of the NULL dev case for non-DMA API callers. Suggested-by: Christoph Hellwig Signed-off-by: Nicolin Chen Acked-by: Niklas Schnelle Acked-by: Michael Ellerman (powerpc) Signed-off-by: Christoph Hellwig --- arch/sparc/kernel/iommu-common.c | 10 +++------- arch/sparc/kernel/iommu.c | 3 +-- arch/sparc/kernel/pci_sun4v.c | 3 +-- 3 files changed, 5 insertions(+), 11 deletions(-) (limited to 'arch/sparc/kernel') diff --git a/arch/sparc/kernel/iommu-common.c b/arch/sparc/kernel/iommu-common.c index 59cb16691322..23ca75f09277 100644 --- a/arch/sparc/kernel/iommu-common.c +++ b/arch/sparc/kernel/iommu-common.c @@ -166,13 +166,6 @@ unsigned long iommu_tbl_range_alloc(struct device *dev, } } - if (dev) - boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, - 1 << iommu->table_shift); - else - boundary_size = ALIGN(1ULL << 32, 1 << iommu->table_shift); - - boundary_size = boundary_size >> iommu->table_shift; /* * if the skip_span_boundary_check had been set during init, we set * things up so that iommu_is_span_boundary() merely checks if the @@ -181,6 +174,9 @@ unsigned long iommu_tbl_range_alloc(struct device *dev, if ((iommu->flags & IOMMU_NO_SPAN_BOUND) != 0) { shift = 0; boundary_size = iommu->poolsize * iommu->nr_pools; + } else { + boundary_size = dma_get_seg_boundary_nr_pages(dev, + iommu->table_shift); } n = iommu_area_alloc(iommu->map, limit, start, npages, shift, boundary_size, align_mask); diff --git a/arch/sparc/kernel/iommu.c b/arch/sparc/kernel/iommu.c index 4ae7388b1bff..c3e4e2df26a8 100644 --- a/arch/sparc/kernel/iommu.c +++ b/arch/sparc/kernel/iommu.c @@ -472,8 +472,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist, outs->dma_length = 0; max_seg_size = dma_get_max_seg_size(dev); - seg_boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, - IO_PAGE_SIZE) >> IO_PAGE_SHIFT; + seg_boundary_size = dma_get_seg_boundary_nr_pages(dev, IO_PAGE_SHIFT); base_shift = iommu->tbl.table_map_base >> IO_PAGE_SHIFT; for_each_sg(sglist, s, nelems, i) { unsigned long paddr, npages, entry, out_entry = 0, slen; diff --git a/arch/sparc/kernel/pci_sun4v.c b/arch/sparc/kernel/pci_sun4v.c index 14b93c5564e3..6b92dd51c002 100644 --- a/arch/sparc/kernel/pci_sun4v.c +++ b/arch/sparc/kernel/pci_sun4v.c @@ -508,8 +508,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist, iommu_batch_start(dev, prot, ~0UL); max_seg_size = dma_get_max_seg_size(dev); - seg_boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, - IO_PAGE_SIZE) >> IO_PAGE_SHIFT; + seg_boundary_size = dma_get_seg_boundary_nr_pages(dev, IO_PAGE_SHIFT); mask = *dev->dma_mask; if (!iommu_use_atu(iommu, mask)) -- cgit v1.2.3