add page sanitization / verification

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 7fb31da45..41a50714f 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -7,6 +7,7 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
+#include <linux/string.h>
 
 #include <asm/cacheflush.h>
 
@@ -189,6 +190,27 @@ static inline void clear_highpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
+static inline void sanitize_highpage(struct page *page)
+{
+	void *kaddr;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	kaddr = kmap_atomic(page);
+	clear_page(kaddr);
+	kunmap_atomic(kaddr);
+	local_irq_restore(flags);
+}
+
+static inline void sanitize_highpage_verify(struct page *page)
+{
+	void *kaddr;
+
+	kaddr = kmap_atomic(page);
+	BUG_ON(memchr_inv(kaddr, 0, PAGE_SIZE));
+	kunmap_atomic(kaddr);
+}
+
 static inline void zero_user_segments(struct page *page,
 	unsigned start1, unsigned end1,
 	unsigned start2, unsigned end2)