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authorChristoph Hellwig <hch@lst.de>2019-07-26 09:26:40 +0200
committerChristoph Hellwig <hch@lst.de>2019-08-10 19:52:45 +0200
commit33dcb37cef741294b481f4d889a465b8091f11bf (patch)
tree129f9cde5b52cd77e04382c99ff0421aa862354b /kernel
parentd8ad55538abe443919e20e0bb996561bca9cad84 (diff)
downloadlinux-33dcb37cef741294b481f4d889a465b8091f11bf.tar.bz2
dma-mapping: fix page attributes for dma_mmap_*
All the way back to introducing dma_common_mmap we've defaulted to mark the pages as uncached. But this is wrong for DMA coherent devices. Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that flag is only treated special on the alloc side for non-coherent devices. Introduce a new dma_pgprot helper that deals with the check for coherent devices so that only the remapping cases ever reach arch_dma_mmap_pgprot and we thus ensure no aliasing of page attributes happens, which makes the powerpc version of arch_dma_mmap_pgprot obsolete and simplifies the remaining ones. Note that this means arch_dma_mmap_pgprot is a bit misnamed now, but we'll phase it out soon. Fixes: 64ccc9c033c6 ("common: dma-mapping: add support for generic dma_mmap_* calls") Reported-by: Shawn Anastasio <shawn@anastas.io> Reported-by: Gavin Li <git@thegavinli.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Catalin Marinas <catalin.marinas@arm.com> # arm64
Diffstat (limited to 'kernel')
-rw-r--r--kernel/dma/mapping.c19
-rw-r--r--kernel/dma/remap.c2
2 files changed, 19 insertions, 2 deletions
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index b945239621d8..b0038ca3aa92 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -150,6 +150,23 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
}
EXPORT_SYMBOL(dma_get_sgtable_attrs);
+#ifdef CONFIG_MMU
+/*
+ * Return the page attributes used for mapping dma_alloc_* memory, either in
+ * kernel space if remapping is needed, or to userspace through dma_mmap_*.
+ */
+pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
+{
+ if (dev_is_dma_coherent(dev) ||
+ (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
+ (attrs & DMA_ATTR_NON_CONSISTENT)))
+ return prot;
+ if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_MMAP_PGPROT))
+ return arch_dma_mmap_pgprot(dev, prot, attrs);
+ return pgprot_noncached(prot);
+}
+#endif /* CONFIG_MMU */
+
/*
* Create userspace mapping for the DMA-coherent memory.
*/
@@ -164,7 +181,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
unsigned long pfn;
int ret = -ENXIO;
- vma->vm_page_prot = arch_dma_mmap_pgprot(dev, vma->vm_page_prot, attrs);
+ vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;
diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
index a594aec07882..ffe78f0b2fe4 100644
--- a/kernel/dma/remap.c
+++ b/kernel/dma/remap.c
@@ -218,7 +218,7 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
/* create a coherent mapping */
ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
- arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
+ dma_pgprot(dev, PAGE_KERNEL, attrs),
__builtin_return_address(0));
if (!ret) {
__dma_direct_free_pages(dev, size, page);