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Commit 15653371 authored by Russell King's avatar Russell King
Browse files

ARM: DMA: Fix struct page iterator in dma_cache_maint() to work with sparsemem 



Subhash Jadavani reported this partial backtrace:
  Now consider this call stack from MMC block driver (this is on the ARMv7
  based board):

  [<c001b50c>] (v7_dma_inv_range+0x30/0x48) from [<c0017b8c>] (dma_cache_maint_page+0x1c4/0x24c)
  [<c0017b8c>] (dma_cache_maint_page+0x1c4/0x24c) from [<c0017c28>] (___dma_page_cpu_to_dev+0x14/0x1c)
  [<c0017c28>] (___dma_page_cpu_to_dev+0x14/0x1c) from [<c0017ff8>] (dma_map_sg+0x3c/0x114)

This is caused by incrementing the struct page pointer, and running off
the end of the sparsemem page array.  Fix this by incrementing by pfn
instead, and convert the pfn to a struct page.

Cc: <stable@vger.kernel.org>
Suggested-by: default avatarJames Bottomley <JBottomley@Parallels.com>
Tested-by: default avatarSubhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 6f16f499

arch/arm/mm/dma-mapping.c

+10 −8
Original line number Diff line number Diff line
@@ -774,25 +774,27 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset, 
	size_t size, enum dma_data_direction dir,

	void (*op)(const void *, size_t, int))

{

	unsigned long pfn;

	size_t left = size;



	pfn = page_to_pfn(page) + offset / PAGE_SIZE;

	offset %= PAGE_SIZE;



	/*

	 * A single sg entry may refer to multiple physically contiguous

	 * pages.  But we still need to process highmem pages individually.

	 * If highmem is not configured then the bulk of this loop gets

	 * optimized out.

	 */

	size_t left = size;

	do {

		size_t len = left;

		void *vaddr;



		page = pfn_to_page(pfn);



		if (PageHighMem(page)) {

			if (len + offset > PAGE_SIZE) {

				if (offset >= PAGE_SIZE) {

					page += offset / PAGE_SIZE;

					offset %= PAGE_SIZE;

				}

			if (len + offset > PAGE_SIZE)

				len = PAGE_SIZE - offset;

			}

			vaddr = kmap_high_get(page);

			if (vaddr) {

				vaddr += offset;
@@ -809,7 +811,7 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset, 
			op(vaddr, len, dir);

		}

		offset = 0;

		page++;

		pfn++;

		left -= len;

	} while (left);

}