x86/mm/32: implement arch_sync_kernel_mappings()

Implement the function to sync changes in vmalloc and ioremap ranges to
all page-tables.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200515140023.25469-6-joro@8bytes.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: joergroedel

arch/x86/include/asm/pgtable-2level_types.h

@@ -20,6 +20,8 @@ typedef union {
 
 #define SHARED_KERNEL_PMD	0
 
+#define ARCH_PAGE_TABLE_SYNC_MASK	PGTBL_PMD_MODIFIED
+
 /*
  * traditional i386 two-level paging structure:
  */

arch/x86/include/asm/pgtable-3level_types.h

@@ -27,6 +27,8 @@ typedef union {
 #define SHARED_KERNEL_PMD	(!static_cpu_has(X86_FEATURE_PTI))
 #endif
 
+#define ARCH_PAGE_TABLE_SYNC_MASK	(SHARED_KERNEL_PMD ? 0 : PGTBL_PMD_MODIFIED)
+
 /*
  * PGDIR_SHIFT determines what a top-level page table entry can map
  */

arch/x86/mm/fault.c

@@ -190,16 +190,13 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
 	return pmd_k;
 }
 
-static void vmalloc_sync(void)
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
 {
-	unsigned long address;
-
-	if (SHARED_KERNEL_PMD)
-		return;
+	unsigned long addr;
 
-	for (address = VMALLOC_START & PMD_MASK;
-	     address >= TASK_SIZE_MAX && address < VMALLOC_END;
-	     address += PMD_SIZE) {
+	for (addr = start & PMD_MASK;
+	     addr >= TASK_SIZE_MAX && addr < VMALLOC_END;
+	     addr += PMD_SIZE) {
 		struct page *page;
 
 		spin_lock(&pgd_lock);
@@ -210,13 +207,23 @@ static void vmalloc_sync(void)
 			pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
 
 			spin_lock(pgt_lock);
-			vmalloc_sync_one(page_address(page), address);
+			vmalloc_sync_one(page_address(page), addr);
 			spin_unlock(pgt_lock);
 		}
 		spin_unlock(&pgd_lock);
 	}
 }
 
+static void vmalloc_sync(void)
+{
+	unsigned long address;
+
+	if (SHARED_KERNEL_PMD)
+		return;
+
+	arch_sync_kernel_mappings(VMALLOC_START, VMALLOC_END);
+}
+
 void vmalloc_sync_mappings(void)
 {
 	vmalloc_sync();