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Commit 9c106119 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Konrad Rzeszutek Wilk
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swiotlb: fix phys_addr_t overflow warning 



On architectures that have a larger dma_addr_t than phys_addr_t,
the swiotlb_tbl_map_single() function truncates its return code
in the failure path, making it impossible to identify the error
later, as we compare to the original value:

kernel/dma/swiotlb.c:551:9: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to 'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]
        return DMA_MAPPING_ERROR;

Use an explicit typecast here to convert it to the narrower type,
and use the same expression in the error handling later.

Fixes: b907e205 ("swiotlb: remove SWIOTLB_MAP_ERROR")
Acked-by: default avatarStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 4e7372e0

drivers/xen/swiotlb-xen.c

+1 −1
Original line number Diff line number Diff line
@@ -408,7 +408,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, 


	map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,

				     attrs);

	if (map == DMA_MAPPING_ERROR)

	if (map == (phys_addr_t)DMA_MAPPING_ERROR)

		return DMA_MAPPING_ERROR;



	dev_addr = xen_phys_to_bus(map);

kernel/dma/swiotlb.c

+2 −2
Original line number Diff line number Diff line
@@ -538,7 +538,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, 
	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())

		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",

			 size, io_tlb_nslabs, tmp_io_tlb_used);

	return DMA_MAPPING_ERROR;

	return (phys_addr_t)DMA_MAPPING_ERROR;

found:

	io_tlb_used += nslots;

	spin_unlock_irqrestore(&io_tlb_lock, flags);
@@ -656,7 +656,7 @@ bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr, 
	/* Oh well, have to allocate and map a bounce buffer. */

	*phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),

			*phys, size, dir, attrs);

	if (*phys == DMA_MAPPING_ERROR)

	if (*phys == (phys_addr_t)DMA_MAPPING_ERROR)

		return false;



	/* Ensure that the address returned is DMA'ble */