[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>

2 files changed, 16 insertions, 8 deletions

diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 81f30ac2bff9..6a24651971df 100644
--- a/arch/mips/mm/cache.c
+++ b/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);
         }
 }
 
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 480dec04f552..c7aed133d11d 100644
--- a/arch/mips/mm/init.c
+++ b/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();