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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 <hch@lst.de>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Nicolin Chen 2020-09-01 15:16:45 -07:00 committed by Christoph Hellwig
parent 2281f797f5
commit 1e9d90dbed
11 changed files with 33 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/alpha/kernel/pci_iommu.c
View File

@ -141,12 +141,7 @@ iommu_arena_find_pages(struct device *dev, struct pci_iommu_arena *arena,
unsigned long boundary_size;
base = arena->dma_base >> PAGE_SHIFT;
if (dev) {
boundary_size = dma_get_seg_boundary(dev) + 1;
boundary_size >>= PAGE_SHIFT;
} else {
boundary_size = 1UL << (32 - PAGE_SHIFT);
}
boundary_size = dma_get_seg_boundary_nr_pages(dev, PAGE_SHIFT);
/* Search forward for the first mask-aligned sequence of N free ptes */
ptes = arena->ptes;

3
arch/ia64/hp/common/sba_iommu.c
View File

@ -485,8 +485,7 @@ sba_search_bitmap(struct ioc *ioc, struct device *dev,
ASSERT(((unsigned long) ioc->res_hint & (sizeof(unsigned long) - 1UL)) == 0);
ASSERT(res_ptr < res_end);
boundary_size = (unsigned long long)dma_get_seg_boundary(dev) + 1;
boundary_size = ALIGN(boundary_size, 1ULL << iovp_shift) >> iovp_shift;
boundary_size = dma_get_seg_boundary_nr_pages(dev, iovp_shift);
BUG_ON(ioc->ibase & ~iovp_mask);
shift = ioc->ibase >> iovp_shift;

11
arch/powerpc/kernel/iommu.c
View File

@ -172,7 +172,6 @@ static unsigned long iommu_range_alloc(struct device *dev,
int largealloc = npages > 15;
int pass = 0;
unsigned long align_mask;
unsigned long boundary_size;
unsigned long flags;
unsigned int pool_nr;
struct iommu_pool *pool;
@ -236,15 +235,9 @@ again:
}
}
if (dev)
boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
1 << tbl->it_page_shift);
else
boundary_size = ALIGN(1UL << 32, 1 << tbl->it_page_shift);
/* 4GB boundary for iseries_hv_alloc and iseries_hv_map */
n = iommu_area_alloc(tbl->it_map, limit, start, npages, tbl->it_offset,
boundary_size >> tbl->it_page_shift, align_mask);
dma_get_seg_boundary_nr_pages(dev, tbl->it_page_shift),
align_mask);
if (n == -1) {
if (likely(pass == 0)) {
/* First try the pool from the start */

6
arch/s390/pci/pci_dma.c
View File

@ -261,13 +261,11 @@ static unsigned long __dma_alloc_iommu(struct device *dev,
unsigned long start, int size)
{
struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
unsigned long boundary_size;
boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
PAGE_SIZE) >> PAGE_SHIFT;
return iommu_area_alloc(zdev->iommu_bitmap, zdev->iommu_pages,
start, size, zdev->start_dma >> PAGE_SHIFT,
boundary_size, 0);
dma_get_seg_boundary_nr_pages(dev, PAGE_SHIFT),
0);
}
static dma_addr_t dma_alloc_address(struct device *dev, int size)

10
arch/sparc/kernel/iommu-common.c
View File

@ -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);

3
arch/sparc/kernel/iommu.c
View File

@ -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;

3
arch/sparc/kernel/pci_sun4v.c
View File

@ -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))

3
arch/x86/kernel/amd_gart_64.c
View File

@ -96,8 +96,7 @@ static unsigned long alloc_iommu(struct device *dev, int size,
base_index = ALIGN(iommu_bus_base & dma_get_seg_boundary(dev),
PAGE_SIZE) >> PAGE_SHIFT;
boundary_size = ALIGN((u64)dma_get_seg_boundary(dev) + 1,
PAGE_SIZE) >> PAGE_SHIFT;
boundary_size = dma_get_seg_boundary_nr_pages(dev, PAGE_SHIFT);
spin_lock_irqsave(&iommu_bitmap_lock, flags);
offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, next_bit,

3
drivers/parisc/ccio-dma.c
View File

@ -356,8 +356,7 @@ ccio_alloc_range(struct ioc *ioc, struct device *dev, size_t size)
** ggg sacrifices another 710 to the computer gods.
*/
boundary_size = ALIGN((unsigned long long)dma_get_seg_boundary(dev) + 1,
1ULL << IOVP_SHIFT) >> IOVP_SHIFT;
boundary_size = dma_get_seg_boundary_nr_pages(dev, IOVP_SHIFT);
if (pages_needed <= 8) {
/*

3
drivers/parisc/sba_iommu.c
View File

@ -342,8 +342,7 @@ sba_search_bitmap(struct ioc *ioc, struct device *dev,
unsigned long shift;
int ret;
boundary_size = ALIGN((unsigned long long)dma_get_seg_boundary(dev) + 1,
1ULL << IOVP_SHIFT) >> IOVP_SHIFT;
boundary_size = dma_get_seg_boundary_nr_pages(dev, IOVP_SHIFT);
#if defined(ZX1_SUPPORT)
BUG_ON(ioc->ibase & ~IOVP_MASK);

19
include/linux/dma-mapping.h
View File

@ -632,6 +632,25 @@ static inline unsigned long dma_get_seg_boundary(struct device *dev)
return DMA_BIT_MASK(32);
}
/**
* dma_get_seg_boundary_nr_pages - return the segment boundary in "page" units
* @dev: device to guery the boundary for
* @page_shift: ilog() of the IOMMU page size
*
* Return the segment boundary in IOMMU page units (which may be different from
* the CPU page size) for the passed in device.
*
* If @dev is NULL a boundary of U32_MAX is assumed, this case is just for
* non-DMA API callers.
*/
static inline unsigned long dma_get_seg_boundary_nr_pages(struct device *dev,
unsigned int page_shift)
{
if (!dev)
return (U32_MAX >> page_shift) + 1;
return (dma_get_seg_boundary(dev) >> page_shift) + 1;
}
static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask)
{
if (dev->dma_parms) {