arm64/mm: drop HAVE_ARCH_PFN_VALID

CONFIG_SPARSEMEM_VMEMMAP is now the only available memory model on arm64
platforms and free_unused_memmap() would just return without creating any
holes in the memmap mapping.  There is no need for any special handling in
pfn_valid() and HAVE_ARCH_PFN_VALID can just be dropped.  This also moves
the pfn upper bits sanity check into generic pfn_valid().

[rppt: rebased on v5.15-rc3]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Anshuman Khandual <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Anshuman Khandual

arch/arm64/Kconfig

@@ -154,7 +154,6 @@ config ARM64
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
-	select HAVE_ARCH_PFN_VALID
 	select HAVE_ARCH_PREL32_RELOCATIONS
 	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
 	select HAVE_ARCH_SECCOMP_FILTER

arch/arm64/include/asm/page.h

@@ -41,7 +41,6 @@ void tag_clear_highpage(struct page *to);
 
 typedef struct page *pgtable_t;
 
-int pfn_valid(unsigned long pfn);
 int pfn_is_map_memory(unsigned long pfn);
 
 #include <asm/memory.h>

arch/arm64/mm/init.c

@@ -160,43 +160,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	free_area_init(max_zone_pfns);
 }
 
-int pfn_valid(unsigned long pfn)
-{
-	phys_addr_t addr = PFN_PHYS(pfn);
-	struct mem_section *ms;
-
-	/*
-	 * Ensure the upper PAGE_SHIFT bits are clear in the
-	 * pfn. Else it might lead to false positives when
-	 * some of the upper bits are set, but the lower bits
-	 * match a valid pfn.
-	 */
-	if (PHYS_PFN(addr) != pfn)
-		return 0;
-
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
-		return 0;
-
-	ms = __pfn_to_section(pfn);
-	if (!valid_section(ms))
-		return 0;
-
-	/*
-	 * ZONE_DEVICE memory does not have the memblock entries.
-	 * memblock_is_map_memory() check for ZONE_DEVICE based
-	 * addresses will always fail. Even the normal hotplugged
-	 * memory will never have MEMBLOCK_NOMAP flag set in their
-	 * memblock entries. Skip memblock search for all non early
-	 * memory sections covering all of hotplug memory including
-	 * both normal and ZONE_DEVICE based.
-	 */
-	if (!early_section(ms))
-		return pfn_section_valid(ms, pfn);
-
-	return memblock_is_memory(addr);
-}
-EXPORT_SYMBOL(pfn_valid);
-
 int pfn_is_map_memory(unsigned long pfn)
 {
 	phys_addr_t addr = PFN_PHYS(pfn);