x86, mm: Separate x86_64 vmalloc_sync_all() into separate functions

No behavior change.

Move some of vmalloc_sync_all() code into a new function
sync_global_pgds() that will be useful for memory hotplug.
Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
LKML-Reference: <4C6E4ECD.1090607@linux.intel.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/pgtable_64.h

@@ -102,6 +102,8 @@ static inline void native_pgd_clear(pgd_t *pgd)
 	native_set_pgd(pgd, native_make_pgd(0));
 }
 
+extern void sync_global_pgds(unsigned long start, unsigned long end);
+
 /*
  * Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.

arch/x86/mm/fault.c

@@ -326,29 +326,7 @@ static void dump_pagetable(unsigned long address)
 
 void vmalloc_sync_all(void)
 {
-	unsigned long address;
-
-	for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END;
-	     address += PGDIR_SIZE) {
-
-		const pgd_t *pgd_ref = pgd_offset_k(address);
-		unsigned long flags;
-		struct page *page;
-
-		if (pgd_none(*pgd_ref))
-			continue;
-
-		spin_lock_irqsave(&pgd_lock, flags);
-		list_for_each_entry(page, &pgd_list, lru) {
-			pgd_t *pgd;
-			pgd = (pgd_t *)page_address(page) + pgd_index(address);
-			if (pgd_none(*pgd))
-				set_pgd(pgd, *pgd_ref);
-			else
-				BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
-		}
-		spin_unlock_irqrestore(&pgd_lock, flags);
-	}
+	sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
 }
 
 /*

arch/x86/mm/init_64.c

@@ -97,6 +97,36 @@ static int __init nonx32_setup(char *str)
 }
 __setup("noexec32=", nonx32_setup);
 
+/*
+ * When memory was added/removed make sure all the processes MM have
+ * suitable PGD entries in the local PGD level page.
+ */
+void sync_global_pgds(unsigned long start, unsigned long end)
+{
+       unsigned long address;
+
+       for (address = start; address <= end; address += PGDIR_SIZE) {
+	       const pgd_t *pgd_ref = pgd_offset_k(address);
+	       unsigned long flags;
+	       struct page *page;
+
+	       if (pgd_none(*pgd_ref))
+		       continue;
+
+	       spin_lock_irqsave(&pgd_lock, flags);
+	       list_for_each_entry(page, &pgd_list, lru) {
+		       pgd_t *pgd;
+		       pgd = (pgd_t *)page_address(page) + pgd_index(address);
+		       if (pgd_none(*pgd))
+			       set_pgd(pgd, *pgd_ref);
+		       else
+			       BUG_ON(pgd_page_vaddr(*pgd)
+					!= pgd_page_vaddr(*pgd_ref));
+	       }
+	       spin_unlock_irqrestore(&pgd_lock, flags);
+       }
+}
+
 /*
  * NOTE: This function is marked __ref because it calls __init function
  * (alloc_bootmem_pages). It's safe to do it ONLY when after_bootmem == 0.