From: Marek Szyprowski m.szyprowski@samsung.com
commit c0f83d164fb8f3a2b7bc379a6c1e27d1123a9eab upstream.
Scatterlist elements contains both pages and DMA addresses, but one should not assume 1:1 relation between them. The sg->length is the size of the physical memory chunk described by the sg->page, while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk described by the sg_dma_address(sg).
The proper way of extracting both: pages and DMA addresses of the whole buffer described by a scatterlist it to iterate independently over the sg->pages/sg->length and sg_dma_address(sg)/sg_dma_len(sg) entries.
Fixes: 42e67b479eab ("drm/prime: use dma length macro when mapping sg") Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Reviewed-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Link: https://patchwork.freedesktop.org/patch/msgid/20200327162126.29705-1-m.szypr... Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/drm_prime.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-)
--- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -962,27 +962,40 @@ int drm_prime_sg_to_page_addr_arrays(str unsigned count; struct scatterlist *sg; struct page *page; - u32 len, index; + u32 page_len, page_index; dma_addr_t addr; + u32 dma_len, dma_index;
- index = 0; + /* + * Scatterlist elements contains both pages and DMA addresses, but + * one shoud not assume 1:1 relation between them. The sg->length is + * the size of the physical memory chunk described by the sg->page, + * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk + * described by the sg_dma_address(sg). + */ + page_index = 0; + dma_index = 0; for_each_sg(sgt->sgl, sg, sgt->nents, count) { - len = sg_dma_len(sg); + page_len = sg->length; page = sg_page(sg); + dma_len = sg_dma_len(sg); addr = sg_dma_address(sg);
- while (len > 0) { - if (WARN_ON(index >= max_entries)) + while (pages && page_len > 0) { + if (WARN_ON(page_index >= max_entries)) return -1; - if (pages) - pages[index] = page; - if (addrs) - addrs[index] = addr; - + pages[page_index] = page; page++; + page_len -= PAGE_SIZE; + page_index++; + } + while (addrs && dma_len > 0) { + if (WARN_ON(dma_index >= max_entries)) + return -1; + addrs[dma_index] = addr; addr += PAGE_SIZE; - len -= PAGE_SIZE; - index++; + dma_len -= PAGE_SIZE; + dma_index++; } } return 0;