sh: Partial revert of copy/clear_user_highpage() optimizations.

These still require more testing, so revert them for now. We keep the
off-by-1 in the fixmap colouring and drop the rest.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/cache.c

@@ -46,18 +46,6 @@ static inline void cacheop_on_each_cpu(void (*func) (void *info), void *info,
 	preempt_enable();
 }
 
-/*
- * copy_to_user_page
- * @vma: vm_area_struct holding the pages
- * @page: struct page
- * @vaddr: user space address
- * @dst: address of page in kernel space (possibly from kmap)
- * @src: source address in kernel logical memory
- * @len: length of data in bytes (may be less than PAGE_SIZE)
- *
- * Copy data into the address space of a process other than the current
- * process (eg for ptrace).
- */
 void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
 		       unsigned long vaddr, void *dst, const void *src,
 		       unsigned long len)
@@ -93,49 +81,28 @@ void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
 	}
 }
 
-/*
- * copy_user_highpage
- * @to: destination page
- * @from: source page
- * @vaddr: address of pages in user address space
- * @vma: vm_area_struct holding the pages
- *
- * This is used in COW implementation to copy data from page @from to
- * page @to. @from was previousl mapped at @vaddr, and @to will be.
- * As this is used only in the COW implementation, this means that the
- * source is unmodified, and so we don't have to worry about cache
- * aliasing on that side.
- */
-#ifdef CONFIG_HIGHMEM
-/*
- * If we ever have a real highmem system, this code will need fixing
- * (as will clear_user/clear_user_highmem), because the kmap potentitally
- * creates another alias risk.
- */
-#error This code is broken with real HIGHMEM
-#endif
 void copy_user_highpage(struct page *to, struct page *from,
 			unsigned long vaddr, struct vm_area_struct *vma)
 {
 	void *vfrom, *vto;
 
 	vto = kmap_atomic(to, KM_USER1);
-	vfrom = kmap_atomic(from, KM_USER0);
-
-	if (pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
-		__flush_invalidate_region(vto, PAGE_SIZE);
 
 	if (boot_cpu_data.dcache.n_aliases && page_mapped(from) &&
 	    !test_bit(PG_dcache_dirty, &from->flags)) {
-		void *vto_coloured = kmap_coherent(to, vaddr);
-		copy_page(vto_coloured, vfrom);
-		kunmap_coherent(vto_coloured);
-	} else
+		vfrom = kmap_coherent(from, vaddr);
 		copy_page(vto, vfrom);
+		kunmap_coherent(vfrom);
+	} else {
+		vfrom = kmap_atomic(from, KM_USER0);
+		copy_page(vto, vfrom);
+		kunmap_atomic(vfrom, KM_USER0);
+	}
 
-	kunmap_atomic(vfrom, KM_USER0);
-	kunmap_atomic(vto, KM_USER1);
+	if (pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
+		__flush_purge_region(vto, PAGE_SIZE);
 
+	kunmap_atomic(vto, KM_USER1);
 	/* Make sure this page is cleared on other CPU's too before using it */
 	smp_wmb();
 }
@@ -145,17 +112,10 @@ void clear_user_highpage(struct page *page, unsigned long vaddr)
 {
 	void *kaddr = kmap_atomic(page, KM_USER0);
 
-	if (pages_do_alias((unsigned long)kaddr, vaddr & PAGE_MASK)) {
-		void *vto;
+	clear_page(kaddr);
 
-		/* Kernel alias may have modified data in the cache. */
-		__flush_invalidate_region(kaddr, PAGE_SIZE);
-
-		vto = kmap_coherent(page, vaddr);
-		clear_page(vto);
-		kunmap_coherent(vto);
-	} else
-		clear_page(kaddr);
+	if (pages_do_alias((unsigned long)kaddr, vaddr & PAGE_MASK))
+		__flush_purge_region(kaddr, PAGE_SIZE);
 
 	kunmap_atomic(kaddr, KM_USER0);
 }