arm64: mm: restrict virt_to_page() to the linear mapping

Now that the vmemmap region has been redefined to cover the linear region
rather than the entire physical address space, we no longer need to
perform a virtual-to-physical translation in the implementaion of
virt_to_page(). This restricts virt_to_page() translations to the linear
region, so redefine virt_addr_valid() as well.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/memory.h

@@ -208,9 +208,19 @@ static inline void *phys_to_virt(phys_addr_t x)
  */
 #define ARCH_PFN_OFFSET		((unsigned long)PHYS_PFN_OFFSET)
 
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
+#else
+#define __virt_to_pgoff(kaddr)	(((u64)(kaddr) & ~PAGE_OFFSET) / PAGE_SIZE * sizeof(struct page))
+#define __page_to_voff(kaddr)	(((u64)(page) & ~VMEMMAP_START) * PAGE_SIZE / sizeof(struct page))
+
+#define page_to_virt(page)	((void *)((__page_to_voff(page)) | PAGE_OFFSET))
+#define virt_to_page(vaddr)	((struct page *)((__virt_to_pgoff(vaddr)) | VMEMMAP_START))
 
+#define virt_addr_valid(kaddr)	pfn_valid((((u64)(kaddr) & ~PAGE_OFFSET) \
+					   + PHYS_OFFSET) >> PAGE_SHIFT)
+#endif
 #endif
 
 #include <asm-generic/memory_model.h>