diff options
Diffstat (limited to 'kernel/dma')
| -rw-r--r-- | kernel/dma/Kconfig | 11 | ||||
| -rw-r--r-- | kernel/dma/debug.c | 2 | ||||
| -rw-r--r-- | kernel/dma/direct.c | 37 | ||||
| -rw-r--r-- | kernel/dma/swiotlb.c | 12 |
4 files changed, 32 insertions, 30 deletions
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index f488997b0717..d62f5957f36b 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -135,6 +135,8 @@ config DMA_COHERENT_POOL config DMA_GLOBAL_POOL select DMA_DECLARE_COHERENT + depends on !ARCH_HAS_DMA_SET_UNCACHED + depends on !DMA_DIRECT_REMAP bool config DMA_DIRECT_REMAP @@ -142,6 +144,15 @@ config DMA_DIRECT_REMAP select DMA_COHERENT_POOL select DMA_NONCOHERENT_MMAP +# +# Fallback to arch code for DMA allocations. This should eventually go away. +# +config ARCH_HAS_DMA_ALLOC + depends on !ARCH_HAS_DMA_SET_UNCACHED + depends on !DMA_DIRECT_REMAP + depends on !DMA_GLOBAL_POOL + bool + config DMA_CMA bool "DMA Contiguous Memory Allocator" depends on HAVE_DMA_CONTIGUOUS && CMA diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 06366acd27b0..3de494375b7b 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -139,7 +139,7 @@ static const char *const maperr2str[] = { static const char *type2name[] = { [dma_debug_single] = "single", - [dma_debug_sg] = "scather-gather", + [dma_debug_sg] = "scatter-gather", [dma_debug_coherent] = "coherent", [dma_debug_resource] = "resource", }; diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 9596ae1aa0da..ed3056eb20b8 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -220,13 +220,7 @@ void *dma_direct_alloc(struct device *dev, size_t size, return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp); if (!dev_is_dma_coherent(dev)) { - /* - * Fallback to the arch handler if it exists. This should - * eventually go away. - */ - if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) && - !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && - !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC) && !is_swiotlb_for_alloc(dev)) return arch_dma_alloc(dev, size, dma_handle, gfp, attrs); @@ -240,27 +234,24 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_handle); /* - * Otherwise remap if the architecture is asking for it. But - * given that remapping memory is a blocking operation we'll - * instead have to dip into the atomic pools. + * Otherwise we require the architecture to either be able to + * mark arbitrary parts of the kernel direct mapping uncached, + * or remapped it uncached. */ + set_uncached = IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED); remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP); - if (remap) { - if (dma_direct_use_pool(dev, gfp)) - return dma_direct_alloc_from_pool(dev, size, - dma_handle, gfp); - } else { - if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED)) - return NULL; - set_uncached = true; + if (!set_uncached && !remap) { + pr_warn_once("coherent DMA allocations not supported on this platform.\n"); + return NULL; } } /* - * Decrypting memory may block, so allocate the memory from the atomic - * pools if we can't block. + * Remapping or decrypting memory may block, allocate the memory from + * the atomic pools instead if we aren't allowed block. */ - if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp)) + if ((remap || force_dma_unencrypted(dev)) && + dma_direct_use_pool(dev, gfp)) return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp); /* we always manually zero the memory once we are done */ @@ -330,9 +321,7 @@ void dma_direct_free(struct device *dev, size_t size, return; } - if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) && - !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && - !IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) && + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC) && !dev_is_dma_coherent(dev) && !is_swiotlb_for_alloc(dev)) { arch_dma_free(dev, size, cpu_addr, dma_addr, attrs); diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index dff067bd56b1..26202274784f 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1301,11 +1301,13 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, pool->slots[index + i].orig_addr = slot_addr(orig_addr, i); tlb_addr = slot_addr(pool->start, index) + offset; /* - * When dir == DMA_FROM_DEVICE we could omit the copy from the orig - * to the tlb buffer, if we knew for sure the device will - * overwrite the entire current content. But we don't. Thus - * unconditional bounce may prevent leaking swiotlb content (i.e. - * kernel memory) to user-space. + * When the device is writing memory, i.e. dir == DMA_FROM_DEVICE, copy + * the original buffer to the TLB buffer before initiating DMA in order + * to preserve the original's data if the device does a partial write, + * i.e. if the device doesn't overwrite the entire buffer. Preserving + * the original data, even if it's garbage, is necessary to match + * hardware behavior. Use of swiotlb is supposed to be transparent, + * i.e. swiotlb must not corrupt memory by clobbering unwritten bytes. */ swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE); return tlb_addr; |