[MIPS] Fix buggy invocations of kmap_coherent()

kmap_coherent will only work correctly if the page it is called on is
not marked dirty.  If it's dirty the kernel address of the page should
be used instead of a temporary mapping.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/cache.c

@@ -92,12 +92,17 @@ EXPORT_SYMBOL(__flush_dcache_page);
 
 void __flush_anon_page(struct page *page, unsigned long vmaddr)
 {
-	if (pages_do_alias((unsigned long)page_address(page), vmaddr)) {
-		void *kaddr;
+	unsigned long addr = (unsigned long) page_address(page);
 
-		kaddr = kmap_coherent(page, vmaddr);
-		flush_data_cache_page((unsigned long)kaddr);
-		kunmap_coherent();
+	if (pages_do_alias(addr, vmaddr)) {
+		if (page_mapped(page) && !Page_dcache_dirty(page)) {
+			void *kaddr;
+
+			kaddr = kmap_coherent(page, vmaddr);
+			flush_data_cache_page((unsigned long)kaddr);
+			kunmap_coherent();
+		} else
+			flush_data_cache_page(addr);
 	}
 }
 

arch/mips/mm/init.c

@@ -211,7 +211,8 @@ void copy_user_highpage(struct page *to, struct page *from,
 	void *vfrom, *vto;
 
 	vto = kmap_atomic(to, KM_USER1);
-	if (cpu_has_dc_aliases && page_mapped(from)) {
+	if (cpu_has_dc_aliases &&
+	    page_mapped(from) && !Page_dcache_dirty(from)) {
 		vfrom = kmap_coherent(from, vaddr);
 		copy_page(vto, vfrom);
 		kunmap_coherent();
@@ -234,7 +235,8 @@ void copy_to_user_page(struct vm_area_struct *vma,
 	struct page *page, unsigned long vaddr, void *dst, const void *src,
 	unsigned long len)
 {
-	if (cpu_has_dc_aliases && page_mapped(page)) {
+	if (cpu_has_dc_aliases &&
+	    page_mapped(page) && !Page_dcache_dirty(page)) {
 		void *vto = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
 		memcpy(vto, src, len);
 		kunmap_coherent();
@@ -253,7 +255,8 @@ void copy_from_user_page(struct vm_area_struct *vma,
 	struct page *page, unsigned long vaddr, void *dst, const void *src,
 	unsigned long len)
 {
-	if (cpu_has_dc_aliases && page_mapped(page)) {
+	if (cpu_has_dc_aliases &&
+	    page_mapped(page) && !Page_dcache_dirty(page)) {
 		void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
 		memcpy(dst, vfrom, len);
 		kunmap_coherent();