[PATCH v7 11/16] mm/highmem: introduce clear_user_highpages()

[Ankur Arora]

Define clear_user_highpages() which clears pages sequentially using
the single page variant.

With !CONFIG_HIGHMEM, pages are contiguous so use the range clearing
primitive clear_user_pages().

Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
---
 include/linux/highmem.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 6234f316468c..ed609987e24d 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -207,6 +207,24 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
 }
 #endif
 
+#ifndef clear_user_highpages
+static inline void clear_user_highpages(struct page *page, unsigned long vaddr,
+					unsigned int npages)
+{
+	if (!IS_ENABLED(CONFIG_HIGHMEM)) {
+		void *base = page_address(page);
+		clear_user_pages(base, vaddr, page, npages);
+		return;
+	}
+
+	do {
+		clear_user_highpage(page, vaddr);
+		vaddr += PAGE_SIZE;
+		page++;
+	} while (--npages);
+}
+#endif
+
 #ifndef vma_alloc_zeroed_movable_folio
 /**
  * vma_alloc_zeroed_movable_folio - Allocate a zeroed page for a VMA.
-- 
2.43.5