patch-2.3.23 linux/include/linux/highmem.h

• Lines: 78
• Date: Fri Oct 22 12:46:21 1999
• Orig file: v2.3.22/linux/include/linux/highmem.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.22/linux/include/linux/highmem.h linux/include/linux/highmem.h
@@ -0,0 +1,77 @@
+#ifndef _LINUX_HIGHMEM_H
+#define _LINUX_HIGHMEM_H
+
+#include <linux/config.h>
+#include <asm/pgtable.h>
+
+#ifdef CONFIG_HIGHMEM
+
+extern struct page *highmem_start_page;
+
+#include <asm/highmem.h>
+
+/* declarations for linux/mm/highmem.c */
+extern unsigned long highmem_mapnr;
+extern unsigned long nr_free_highpages;
+
+extern struct page * prepare_highmem_swapout(struct page *);
+extern struct page * replace_with_highmem(struct page *);
+
+#else /* CONFIG_HIGHMEM */
+
+#define prepare_highmem_swapout(page) page
+#define replace_with_highmem(page) page
+#define kmap(page, type) page_address(page)
+#define kunmap(vaddr, type) do { } while (0)
+#define nr_free_highpages 0UL
+
+#endif /* CONFIG_HIGHMEM */
+
+/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
+extern inline void clear_highpage(struct page *page)
+{
+	unsigned long kaddr;
+
+	kaddr = kmap(page, KM_WRITE);
+	clear_page((void *)kaddr);
+	kunmap(kaddr, KM_WRITE);
+}
+
+extern inline void memclear_highpage(struct page *page, unsigned int offset, unsigned int size)
+{
+	unsigned long kaddr;
+
+	if (offset + size > PAGE_SIZE)
+		BUG();
+	kaddr = kmap(page, KM_WRITE);
+	memset((void *)(kaddr + offset), 0, size);
+	kunmap(kaddr, KM_WRITE);
+}
+
+/*
+ * Same but also flushes aliased cache contents to RAM.
+ */
+extern inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
+{
+	unsigned long kaddr;
+
+	if (offset + size > PAGE_SIZE)
+		BUG();
+	kaddr = kmap(page, KM_WRITE);
+	memset((void *)(kaddr + offset), 0, size);
+	flush_page_to_ram(page);
+	kunmap(kaddr, KM_WRITE);
+}
+
+extern inline void copy_highpage(struct page *to, struct page *from)
+{
+	unsigned long vfrom, vto;
+
+	vfrom = kmap(from, KM_READ);
+	vto = kmap(to, KM_WRITE);
+	copy_page((void *)vto, (void *)vfrom);
+	kunmap(vfrom, KM_READ);
+	kunmap(vto, KM_WRITE);
+}
+
+#endif /* _LINUX_HIGHMEM_H */