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dma-direct: provide mmap and get_sgtable method overrides

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For dma-direct we know that the DMA address is an encoding of the
physical address that we can trivially decode.  Use that fact to
provide implementations that do not need the arch_dma_coherent_to_pfn
architecture hook.  Note that we still can only support mmap of
non-coherent memory only if the architecture provides a way to set an
uncached bit in the page tables.  This must be true for architectures
that use the generic remap helpers, but other architectures can also
manually select it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Christoph Hellwig
2019-10-29 11:01:37 +01:00
parent 4e1003aa56
commit 34dc0ea6bc
16 changed files with 85 additions and 75 deletions
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45
kernel/dma/mapping.c
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@@ -112,24 +112,9 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs)
{
struct page *page;
struct page *page = virt_to_page(cpu_addr);
int ret;
if (!dev_is_dma_coherent(dev)) {
unsigned long pfn;
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN))
return -ENXIO;
/* If the PFN is not valid, we do not have a struct page */
pfn = arch_dma_coherent_to_pfn(dev, cpu_addr, dma_addr);
if (!pfn_valid(pfn))
return -ENXIO;
page = pfn_to_page(pfn);
} else {
page = virt_to_page(cpu_addr);
}
ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
if (!ret)
sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
@@ -154,7 +139,7 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dma_is_direct(ops))
return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr,
return dma_direct_get_sgtable(dev, sgt, cpu_addr, dma_addr,
size, attrs);
if (!ops->get_sgtable)
return -ENXIO;
@@ -192,7 +177,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
unsigned long user_count = vma_pages(vma);
unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
unsigned long off = vma->vm_pgoff;
unsigned long pfn;
int ret = -ENXIO;
vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
@@ -203,19 +187,8 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
if (off >= count || user_count > count - off)
return -ENXIO;
if (!dev_is_dma_coherent(dev)) {
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN))
return -ENXIO;
/* If the PFN is not valid, we do not have a struct page */
pfn = arch_dma_coherent_to_pfn(dev, cpu_addr, dma_addr);
if (!pfn_valid(pfn))
return -ENXIO;
} else {
pfn = page_to_pfn(virt_to_page(cpu_addr));
}
return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
return remap_pfn_range(vma, vma->vm_start,
page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
user_count << PAGE_SHIFT, vma->vm_page_prot);
#else
return -ENXIO;
@@ -233,12 +206,8 @@ bool dma_can_mmap(struct device *dev)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dma_is_direct(ops)) {
return IS_ENABLED(CONFIG_MMU) &&
(dev_is_dma_coherent(dev) ||
IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN));
}
if (dma_is_direct(ops))
return dma_direct_can_mmap(dev);
return ops->mmap != NULL;
}
EXPORT_SYMBOL_GPL(dma_can_mmap);
@@ -263,7 +232,7 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dma_is_direct(ops))
return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size,
return dma_direct_mmap(dev, vma, cpu_addr, dma_addr, size,
attrs);
if (!ops->mmap)
return -ENXIO;