From: Russell King Date: Sat, 31 Oct 2009 16:52:16 +0000 (+0000) Subject: ARM: dma-mapping: fix for speculative prefetching X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2ffe2da3e71652d4f4cae19539b5c78c2a239136;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git ARM: dma-mapping: fix for speculative prefetching ARMv6 and ARMv7 CPUs can perform speculative prefetching, which makes DMA cache coherency handling slightly more interesting. Rather than being able to rely upon the CPU not accessing the DMA buffer until DMA has completed, we now must expect that the cache could be loaded with possibly stale data from the DMA buffer. Where DMA involves data being transferred to the device, we clean the cache before handing it over for DMA, otherwise we invalidate the buffer to get rid of potential writebacks. On DMA Completion, if data was transferred from the device, we invalidate the buffer to get rid of any stale speculative prefetches. Signed-off-by: Russell King Tested-By: Santosh Shilimkar --- diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S index a11934e53fbd..9d89c67a1cc3 100644 --- a/arch/arm/mm/cache-v6.S +++ b/arch/arm/mm/cache-v6.S @@ -271,10 +271,9 @@ ENTRY(v6_dma_flush_range) */ ENTRY(v6_dma_map_area) add r1, r1, r0 - cmp r2, #DMA_TO_DEVICE - beq v6_dma_clean_range - bcs v6_dma_inv_range - b v6_dma_flush_range + teq r2, #DMA_FROM_DEVICE + beq v6_dma_inv_range + b v6_dma_clean_range ENDPROC(v6_dma_map_area) /* @@ -284,6 +283,9 @@ ENDPROC(v6_dma_map_area) * - dir - DMA direction */ ENTRY(v6_dma_unmap_area) + add r1, r1, r0 + teq r2, #DMA_TO_DEVICE + bne v6_dma_inv_range mov pc, lr ENDPROC(v6_dma_unmap_area) diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S index b1cd0fd91207..bcd64f265870 100644 --- a/arch/arm/mm/cache-v7.S +++ b/arch/arm/mm/cache-v7.S @@ -279,10 +279,9 @@ ENDPROC(v7_dma_flush_range) */ ENTRY(v7_dma_map_area) add r1, r1, r0 - cmp r2, #DMA_TO_DEVICE - beq v7_dma_clean_range - bcs v7_dma_inv_range - b v7_dma_flush_range + teq r2, #DMA_FROM_DEVICE + beq v7_dma_inv_range + b v7_dma_clean_range ENDPROC(v7_dma_map_area) /* @@ -292,6 +291,9 @@ ENDPROC(v7_dma_map_area) * - dir - DMA direction */ ENTRY(v7_dma_unmap_area) + add r1, r1, r0 + teq r2, #DMA_TO_DEVICE + bne v7_dma_inv_range mov pc, lr ENDPROC(v7_dma_unmap_area) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index efa8efa33f5e..64daef2173bd 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -404,34 +404,22 @@ EXPORT_SYMBOL(dma_free_coherent); * platforms with CONFIG_DMABOUNCE. * Use the driver DMA support - see dma-mapping.h (dma_sync_*) */ -static void dma_cache_maint(const void *start, size_t size, int direction) -{ - void (*outer_op)(unsigned long, unsigned long); - - switch (direction) { - case DMA_FROM_DEVICE: /* invalidate only */ - outer_op = outer_inv_range; - break; - case DMA_TO_DEVICE: /* writeback only */ - outer_op = outer_clean_range; - break; - case DMA_BIDIRECTIONAL: /* writeback and invalidate */ - outer_op = outer_flush_range; - break; - default: - BUG(); - } - - outer_op(__pa(start), __pa(start) + size); -} - void ___dma_single_cpu_to_dev(const void *kaddr, size_t size, enum dma_data_direction dir) { + unsigned long paddr; + BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1)); dmac_map_area(kaddr, size, dir); - dma_cache_maint(kaddr, size, dir); + + paddr = __pa(kaddr); + if (dir == DMA_FROM_DEVICE) { + outer_inv_range(paddr, paddr + size); + } else { + outer_clean_range(paddr, paddr + size); + } + /* FIXME: non-speculating: flush on bidirectional mappings? */ } EXPORT_SYMBOL(___dma_single_cpu_to_dev); @@ -440,6 +428,13 @@ void ___dma_single_dev_to_cpu(const void *kaddr, size_t size, { BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1)); + /* FIXME: non-speculating: not required */ + /* don't bother invalidating if DMA to device */ + if (dir != DMA_TO_DEVICE) { + unsigned long paddr = __pa(kaddr); + outer_inv_range(paddr, paddr + size); + } + dmac_unmap_area(kaddr, size, dir); } EXPORT_SYMBOL(___dma_single_dev_to_cpu); @@ -487,32 +482,29 @@ void ___dma_page_cpu_to_dev(struct page *page, unsigned long off, size_t size, enum dma_data_direction dir) { unsigned long paddr; - void (*outer_op)(unsigned long, unsigned long); - - switch (direction) { - case DMA_FROM_DEVICE: /* invalidate only */ - outer_op = outer_inv_range; - break; - case DMA_TO_DEVICE: /* writeback only */ - outer_op = outer_clean_range; - break; - case DMA_BIDIRECTIONAL: /* writeback and invalidate */ - outer_op = outer_flush_range; - break; - default: - BUG(); - } dma_cache_maint_page(page, off, size, dir, dmac_map_area); paddr = page_to_phys(page) + off; - outer_op(paddr, paddr + size); + if (dir == DMA_FROM_DEVICE) { + outer_inv_range(paddr, paddr + size); + } else { + outer_clean_range(paddr, paddr + size); + } + /* FIXME: non-speculating: flush on bidirectional mappings? */ } EXPORT_SYMBOL(___dma_page_cpu_to_dev); void ___dma_page_dev_to_cpu(struct page *page, unsigned long off, size_t size, enum dma_data_direction dir) { + unsigned long paddr = page_to_phys(page) + off; + + /* FIXME: non-speculating: not required */ + /* don't bother invalidating if DMA to device */ + if (dir != DMA_TO_DEVICE) + outer_inv_range(paddr, paddr + size); + dma_cache_maint_page(page, off, size, dir, dmac_unmap_area); } EXPORT_SYMBOL(___dma_page_dev_to_cpu);