1 files changed, 55 insertions, 14 deletions

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index cf6240741134..ca6d268e3313 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/sched.h>
+#include <linux/vmalloc.h>
 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
@@ -36,14 +37,32 @@ static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
 	return 0;
 }
 
+/*
+ * This function assumes that the range is mapped with PAGE_SIZE pages.
+ */
+static int __change_memory_common(unsigned long start, unsigned long size,
+				pgprot_t set_mask, pgprot_t clear_mask)
+{
+	struct page_change_data data;
+	int ret;
+
+	data.set_mask = set_mask;
+	data.clear_mask = clear_mask;
+
+	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+					&data);
+
+	flush_tlb_kernel_range(start, start + size);
+	return ret;
+}
+
 static int change_memory_common(unsigned long addr, int numpages,
 				pgprot_t set_mask, pgprot_t clear_mask)
 {
 	unsigned long start = addr;
 	unsigned long size = PAGE_SIZE*numpages;
 	unsigned long end = start + size;
-	int ret;
-	struct page_change_data data;
+	struct vm_struct *area;
 
 	if (!PAGE_ALIGNED(addr)) {
 		start &= PAGE_MASK;
@@ -51,23 +70,29 @@ static int change_memory_common(unsigned long addr, int numpages,
 		WARN_ON_ONCE(1);
 	}
 
-	if (start < MODULES_VADDR || start >= MODULES_END)
-		return -EINVAL;
-
-	if (end < MODULES_VADDR || end >= MODULES_END)
+	/*
+	 * Kernel VA mappings are always live, and splitting live section
+	 * mappings into page mappings may cause TLB conflicts. This means
+	 * we have to ensure that changing the permission bits of the range
+	 * we are operating on does not result in such splitting.
+	 *
+	 * Let's restrict ourselves to mappings created by vmalloc (or vmap).
+	 * Those are guaranteed to consist entirely of page mappings, and
+	 * splitting is never needed.
+	 *
+	 * So check whether the [addr, addr + size) interval is entirely
+	 * covered by precisely one VM area that has the VM_ALLOC flag set.
+	 */
+	area = find_vm_area((void *)addr);
+	if (!area ||
+	    end > (unsigned long)area->addr + area->size ||
+	    !(area->flags & VM_ALLOC))
 		return -EINVAL;
 
 	if (!numpages)
 		return 0;
 
-	data.set_mask = set_mask;
-	data.clear_mask = clear_mask;
-
-	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
-					&data);
-
-	flush_tlb_kernel_range(start, end);
-	return ret;
+	return __change_memory_common(start, size, set_mask, clear_mask);
 }
 
 int set_memory_ro(unsigned long addr, int numpages)
@@ -99,3 +124,19 @@ int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(PTE_PXN));
 }
 EXPORT_SYMBOL_GPL(set_memory_x);
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+void __kernel_map_pages(struct page *page, int numpages, int enable)
+{
+	unsigned long addr = (unsigned long) page_address(page);
+
+	if (enable)
+		__change_memory_common(addr, PAGE_SIZE * numpages,
+					__pgprot(PTE_VALID),
+					__pgprot(0));
+	else
+		__change_memory_common(addr, PAGE_SIZE * numpages,
+					__pgprot(0),
+					__pgprot(PTE_VALID));
+}
+#endif