diff options
| -rw-r--r-- | lib/Kconfig.debug | 17 | ||||
| -rw-r--r-- | lib/dma-debug.c | 28 |
2 files changed, 45 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index d5175eb7b917..76555479ae36 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1651,6 +1651,23 @@ config DMA_API_DEBUG If unsure, say N. +config DMA_API_DEBUG_SG + bool "Debug DMA scatter-gather usage" + default y + depends on DMA_API_DEBUG + help + Perform extra checking that callers of dma_map_sg() have respected the + appropriate segment length/boundary limits for the given device when + preparing DMA scatterlists. + + This is particularly likely to have been overlooked in cases where the + dma_map_sg() API is used for general bulk mapping of pages rather than + preparing literal scatter-gather descriptors, where there is a risk of + unexpected behaviour from DMA API implementations if the scatterlist + is technically out-of-spec. + + If unsure, say N. + menuconfig RUNTIME_TESTING_MENU bool "Runtime Testing" def_bool y diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 6a1ebaa83623..c007d25bee09 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -1286,6 +1286,32 @@ out: put_hash_bucket(bucket, &flags); } +static void check_sg_segment(struct device *dev, struct scatterlist *sg) +{ +#ifdef CONFIG_DMA_API_DEBUG_SG + unsigned int max_seg = dma_get_max_seg_size(dev); + u64 start, end, boundary = dma_get_seg_boundary(dev); + + /* + * Either the driver forgot to set dma_parms appropriately, or + * whoever generated the list forgot to check them. + */ + if (sg->length > max_seg) + err_printk(dev, NULL, "DMA-API: mapping sg segment longer than device claims to support [len=%u] [max=%u]\n", + sg->length, max_seg); + /* + * In some cases this could potentially be the DMA API + * implementation's fault, but it would usually imply that + * the scatterlist was built inappropriately to begin with. + */ + start = sg_dma_address(sg); + end = start + sg_dma_len(sg) - 1; + if ((start ^ end) & ~boundary) + err_printk(dev, NULL, "DMA-API: mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n", + start, end, boundary); +#endif +} + void debug_dma_map_page(struct device *dev, struct page *page, size_t offset, size_t size, int direction, dma_addr_t dma_addr, bool map_single) @@ -1416,6 +1442,8 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg, check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s)); } + check_sg_segment(dev, s); + add_dma_entry(entry); } } |