From: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx> To prepare for the introduction of dynamically allocated bounce buffers, separate out common code and code which handles non-dynamic (aka fixed) bounce buffers. No functional change, but this commit should make the addition of dynamic allocations easier to review. Signed-off-by: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx> --- include/linux/swiotlb.h | 31 ++++++++++- kernel/dma/swiotlb.c | 110 +++++++++++++++++++++++++++++++++------- 2 files changed, 122 insertions(+), 19 deletions(-) diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index b65b7330f7e5..a0bb6b30b17c 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -105,11 +105,40 @@ struct io_tlb_mem { }; extern struct io_tlb_mem io_tlb_default_mem; +/** + * is_swiotlb_fixed() - check if a physical address belongs to a swiotlb slot + * @mem: relevant swiotlb pool + * @paddr: physical address within the DMA buffer + * + * Check if @paddr points into a fixed bounce buffer slot. + * This check should be as fast as possible. + * + * Return: + * * %true if @paddr points into a @mem fixed slot + * * %false otherwise + */ +static inline bool is_swiotlb_fixed(struct io_tlb_mem *mem, phys_addr_t paddr) +{ + return paddr >= mem->start && paddr < mem->end; +} + +/** + * is_swiotlb_buffer() - check if a physical address is allocated from the + * swiotlb pool + * @dev: device which has mapped the buffer + * @paddr: physical address within the DMA buffer + * + * Check if @paddr points into a bounce buffer. + * + * Return: + * * %true if @paddr points into a bounce buffer + * * %false otherwise + */ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr) { struct io_tlb_mem *mem = dev->dma_io_tlb_mem; - return mem && paddr >= mem->start && paddr < mem->end; + return mem && is_swiotlb_fixed(mem, paddr); } static inline bool is_swiotlb_force_bounce(struct device *dev) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index dac42a2ad588..2f09a4ed4215 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -78,6 +78,10 @@ phys_addr_t swiotlb_unencrypted_base; static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT; static unsigned long default_nareas; +static void swiotlb_copy(struct device *dev, phys_addr_t orig_addr, + unsigned char *vaddr, size_t size, size_t alloc_size, + unsigned int tlb_offset, enum dma_data_direction dir); + /** * struct io_tlb_area - IO TLB memory area descriptor * @@ -523,7 +527,6 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT; phys_addr_t orig_addr = mem->slots[index].orig_addr; size_t alloc_size = mem->slots[index].alloc_size; - unsigned long pfn = PFN_DOWN(orig_addr); unsigned char *vaddr = mem->vaddr + tlb_addr - mem->start; unsigned int tlb_offset, orig_addr_offset; @@ -540,6 +543,34 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size } tlb_offset -= orig_addr_offset; + swiotlb_copy(dev, orig_addr, vaddr, size, alloc_size, tlb_offset, dir); +} + +/** + * swiotlb_copy() - copy swiotlb buffer content, checking for overflows. + * @dev: device which has mapped the bounce buffer + * @orig_addr: physical address of the original buffer + * @vaddr: virtual address inside the bounce buffer + * @size: number of bytes to copy + * @alloc_size: total allocated size of the bounce buffer + * @tlb_offset: offset within the bounce buffer + * @dir: direction of the data transfer + * + * If @dir is %DMA_TO_DEVICE, copy data from the original buffer to the + * bounce buffer, otherwise copy from the bounce buffer to the original + * buffer. + * + * The original buffer may be in high memory; that's why @orig_addr is + * a physical address. Note that this is the address of the beginning + * of the bounce buffer. Copying starts at offset @tlb_offset. This is + * needed to check accesses beyond the allocated size. + */ +static void swiotlb_copy(struct device *dev, phys_addr_t orig_addr, + unsigned char *vaddr, size_t size, size_t alloc_size, + unsigned int tlb_offset, enum dma_data_direction dir) +{ + unsigned long pfn = PFN_DOWN(orig_addr); + if (tlb_offset > alloc_size) { dev_WARN_ONCE(dev, 1, "Buffer overflow detected. Allocation size: %zu. Mapping size: %zu+%u.\n", @@ -734,15 +765,65 @@ static unsigned long mem_used(struct io_tlb_mem *mem) return used; } +/** + * swiotlb_fixed_map() - allocate a bounce buffer from fixed slots + * @dev: device which maps the buffer + * @orig_addr: address of the original buffer + * @alloc_size: total size of the original buffer + * @alloc_align_mask: + * required physical alignment of the I/O buffer + * @attrs: optional DMA attributes for the map operation + * + * Search for a suitable slot or sequence of slots and initialize them + * for use with the original buffer. + * + * Return: Physical address of the bounce buffer, or %DMA_MAPPING_ERROR. + */ +static phys_addr_t swiotlb_fixed_map(struct device *dev, phys_addr_t orig_addr, + size_t alloc_size, unsigned int alloc_align_mask, + unsigned long attrs) +{ + struct io_tlb_mem *mem = dev->dma_io_tlb_mem; + unsigned int offset = swiotlb_align_offset(dev, orig_addr); + int index = swiotlb_find_slots(dev, orig_addr, + alloc_size + offset, alloc_align_mask); + unsigned int i; + + if (index == -1) + return (phys_addr_t)DMA_MAPPING_ERROR; + + /* + * Save away the mapping from the original address to the DMA address. + * This is needed when we sync the memory. Then we sync the buffer if + * needed. + */ + for (i = 0; i < nr_slots(alloc_size + offset); i++) + mem->slots[index + i].orig_addr = slot_addr(orig_addr, i); + return slot_addr(mem->start, index) + offset; +} + +/** + * swiotlb_tbl_map_single() - map DMA buffer to a bounce buffer + * @dev: device which maps the buffer + * @orig_addr: address of the original buffer + * @mapping_size: size of the original buffer to be synced now + * @alloc_size: total size of the original buffer + * @alloc_align_mask: + * required physical alignment of the I/O buffer + * @dir: direction of the data transfer + * @attrs: optional DMA attributes for the map operation + * + * Create a mapping of the DMA buffer into a bounce buffer and copy the + * original data. + * + * Return: Physical address of the bounce buffer, or %DMA_MAPPING_ERROR. + */ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, size_t mapping_size, size_t alloc_size, unsigned int alloc_align_mask, enum dma_data_direction dir, unsigned long attrs) { struct io_tlb_mem *mem = dev->dma_io_tlb_mem; - unsigned int offset = swiotlb_align_offset(dev, orig_addr); - unsigned int i; - int index; phys_addr_t tlb_addr; if (!mem || !mem->nslabs) { @@ -760,24 +841,17 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, return (phys_addr_t)DMA_MAPPING_ERROR; } - index = swiotlb_find_slots(dev, orig_addr, - alloc_size + offset, alloc_align_mask); - if (index == -1) { + tlb_addr = swiotlb_fixed_map(dev, orig_addr, alloc_size, + alloc_align_mask, attrs); + + if (tlb_addr == (phys_addr_t)DMA_MAPPING_ERROR) { if (!(attrs & DMA_ATTR_NO_WARN)) dev_warn_ratelimited(dev, - "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n", - alloc_size, mem->nslabs, mem_used(mem)); - return (phys_addr_t)DMA_MAPPING_ERROR; + "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n", + alloc_size, mem->nslabs, mem_used(mem)); + return tlb_addr; } - /* - * Save away the mapping from the original address to the DMA address. - * This is needed when we sync the memory. Then we sync the buffer if - * needed. - */ - for (i = 0; i < nr_slots(alloc_size + offset); i++) - mem->slots[index + i].orig_addr = slot_addr(orig_addr, i); - tlb_addr = slot_addr(mem->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 -- 2.25.1