swiotlb: Skip cache maintenance on map error

rmurphy-arm · Christoph Hellwig · commit cb216b84d6ea · 2018-11-21T18:47:58.000+01:00
If swiotlb_bounce_page() failed, calling arch_sync_dma_for_device() may lead to such delights as performing cache maintenance on whatever address phys_to_virt(SWIOTLB_MAP_ERROR) looks like, which is typically outside the kernel memory map and goes about as well as expected. Don't do that. Fixes: a4a4330 ("swiotlb: add support for non-coherent DMA") Tested-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
@@ -679,7 +679,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	}
 
 	if (!dev_is_dma_coherent(dev) &&
-	    (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
+	    (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 &&
+	    dev_addr != DIRECT_MAPPING_ERROR)
 		arch_sync_dma_for_device(dev, phys, size, dir);
 
 	return dev_addr;

Original file line number	Diff line number	Diff line change
`@@ -679,7 +679,8 @@ dma_addr_t swiotlb_map_page(struct device dev, struct page page,`
`679`	`679`	`}`
`680`	`680`
`681`	`681`	`if (!dev_is_dma_coherent(dev) &&`
`682`		`- (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)`
	`682`	`+ (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 &&`
	`683`	`+ dev_addr != DIRECT_MAPPING_ERROR)`
`683`	`684`	`arch_sync_dma_for_device(dev, phys, size, dir);`
`684`	`685`
`685`	`686`	`return dev_addr;`