RISC-V: Avoid corrupting the upper 32-bit of phys_addr_t in ioremap

[ Upstream commit 827a438156e4c423b6875a092e272933952a2910 ]

For 32bit, the upper 32-bit of phys_addr_t will be flushed to zero
after AND with PAGE_MASK because the data type of PAGE_MASK is
unsigned long. To fix this problem, the page alignment is done by
subtracting the page offset instead of AND with PAGE_MASK.
Signed-off-by: NVincent Chen <vincentc@andestech.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

arch/riscv/mm/ioremap.c

@@ -42,7 +42,7 @@ static void __iomem *__ioremap_caller(phys_addr_t addr, size_t size,
 
 	/* Page-align mappings */
 	offset = addr & (~PAGE_MASK);
-	addr &= PAGE_MASK;
+	addr -= offset;
 	size = PAGE_ALIGN(size + offset);
 
 	area = get_vm_area_caller(size, VM_IOREMAP, caller);