sparc: Fix page alignment in dma mapping

'phys' may include an offset within the page, while previously used
'base_paddr' was already page-aligned. This caused incorrect DMA mapping
in dma_4u_map_phys and dma_4v_map_phys.

Fix both functions by masking 'phys' with IO_PAGE_MASK, covering both
generic SPARC code and sun4v.

Fixes: 38c0d0e ("sparc: Use physical address DMA mapping")
Reported-by: Stian Halseth <stian@itx.no>
Closes: sparclinux/issues#75
Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Stian Halseth <stian@itx.no>
Tested-by: Nathaniel Roach <nroach44@nroach44.id.au>
Tested-by: Han Gao <gaohan@iscas.ac.cn> # on SPARC Enterprise T5220
[mszyprow: adjusted commit description a bit]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260218120056.3366-2-stian@itx.no

Author: shalseth

arch/sparc/kernel/iommu.c

@@ -312,6 +312,8 @@ static dma_addr_t dma_4u_map_phys(struct device *dev, phys_addr_t phys,
 	if (direction != DMA_TO_DEVICE)
 		iopte_protection |= IOPTE_WRITE;
 
+	phys &= IO_PAGE_MASK;
+
 	for (i = 0; i < npages; i++, base++, phys += IO_PAGE_SIZE)
 		iopte_val(*base) = iopte_protection | phys;
 

arch/sparc/kernel/pci_sun4v.c

@@ -410,6 +410,8 @@ static dma_addr_t dma_4v_map_phys(struct device *dev, phys_addr_t phys,
 
 	iommu_batch_start(dev, prot, entry);
 
+	phys &= IO_PAGE_MASK;
+
 	for (i = 0; i < npages; i++, phys += IO_PAGE_SIZE) {
 		long err = iommu_batch_add(phys, mask);
 		if (unlikely(err < 0L))