From 31b931bebd11a0f00967114f62c8c38952f483e5 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sun, 7 Dec 2025 19:47:56 +0100 Subject: [PATCH] dma-mapping: Fix DMA_BIT_MASK() macro being broken After commit a50f7456f853 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope"), the DMA_BIT_MASK() macro is broken when passed non trivial statements for the value of 'n'. This is caused by the new version missing parenthesis around 'n' when evaluating 'n'. One example of this breakage is the IPU6 driver now crashing due to it getting DMA-addresses with address bit 32 set even though it has tried to set a 32 bit DMA mask. The IPU6 CSI2 engine has a DMA mask of either 31 or 32 bits depending on if it is in secure mode or not and it sets this masks like this: mmu_info->aperture_end = (dma_addr_t)DMA_BIT_MASK(isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE); So the 'n' argument here is "isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE" which gets expanded into: isp->secure_mode ? IPU6_MMU_ADDR_BITS : IPU6_MMU_ADDR_BITS_NON_SECURE - 1 With the -1 only being applied in the non secure case, causing the secure mode mask to be one 1 bit too large. Fixes: a50f7456f853 ("dma-mapping: Allow use of DMA_BIT_MASK(64) in global scope") Cc: Sakari Ailus Cc: James Clark Cc: Nathan Chancellor Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede Reviewed-by: Nathan Chancellor Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20251207184756.97904-1-johannes.goede@oss.qualcomm.com --- include/linux/dma-mapping.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 2ceda49c609fb..aa36a0d1d9df6 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -90,7 +90,7 @@ */ #define DMA_MAPPING_ERROR (~(dma_addr_t)0) -#define DMA_BIT_MASK(n) GENMASK_ULL(n - 1, 0) +#define DMA_BIT_MASK(n) GENMASK_ULL((n) - 1, 0) struct dma_iova_state { dma_addr_t addr; -- 2.47.3