1 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 8490ed2917ff..1fdb7bb7c198 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -219,6 +219,43 @@ 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);