1 files changed, 138 insertions, 0 deletions
diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
new file mode 100644
index 0000000000..a1a71f36d8
--- /dev/null
+++ b/arch/arm/mm/copypage-v6.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/mm/copypage-v6.c
+ *
+ *  Copyright (C) 2002 Deep Blue Solutions Ltd, All Rights Reserved.
+ */
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+
+#include <asm/shmparam.h>
+#include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
+#include <asm/cachetype.h>
+
+#include "mm.h"
+
+#if SHMLBA > 16384
+#error FIX ME
+#endif
+
+static DEFINE_RAW_SPINLOCK(v6_lock);
+
+/*
+ * Copy the user page.  No aliasing to deal with so we can just
+ * attack the kernel's existing mapping of these pages.
+ */
+static void v6_copy_user_highpage_nonaliasing(struct page *to,
+	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
+{
+	void *kto, *kfrom;
+
+	kfrom = kmap_atomic(from);
+	kto = kmap_atomic(to);
+	copy_page(kto, kfrom);
+	kunmap_atomic(kto);
+	kunmap_atomic(kfrom);
+}
+
+/*
+ * Clear the user page.  No aliasing to deal with so we can just
+ * attack the kernel's existing mapping of this page.
+ */
+static void v6_clear_user_highpage_nonaliasing(struct page *page, unsigned long vaddr)
+{
+	void *kaddr = kmap_atomic(page);
+	clear_page(kaddr);
+	kunmap_atomic(kaddr);
+}
+
+/*
+ * Discard data in the kernel mapping for the new page.
+ * FIXME: needs this MCRR to be supported.
+ */
+static void discard_old_kernel_data(void *kto)
+{
+	__asm__("mcrr	p15, 0, %1, %0, c6	@ 0xec401f06"
+	   :
+	   : "r" (kto),
+	     "r" ((unsigned long)kto + PAGE_SIZE - 1)
+	   : "cc");
+}
+
+/*
+ * Copy the page, taking account of the cache colour.
+ */
+static void v6_copy_user_highpage_aliasing(struct page *to,
+	struct page *from, unsigned long vaddr, struct vm_area_struct *vma)
+{
+	struct folio *src = page_folio(from);
+	unsigned int offset = CACHE_COLOUR(vaddr);
+	unsigned long kfrom, kto;
+
+	if (!test_and_set_bit(PG_dcache_clean, &src->flags))
+		__flush_dcache_folio(folio_flush_mapping(src), src);
+
+	/* FIXME: not highmem safe */
+	discard_old_kernel_data(page_address(to));
+
+	/*
+	 * Now copy the page using the same cache colour as the
+	 * pages ultimate destination.
+	 */
+	raw_spin_lock(&v6_lock);
+
+	kfrom = COPYPAGE_V6_FROM + (offset << PAGE_SHIFT);
+	kto   = COPYPAGE_V6_TO + (offset << PAGE_SHIFT);
+
+	set_top_pte(kfrom, mk_pte(from, PAGE_KERNEL));
+	set_top_pte(kto, mk_pte(to, PAGE_KERNEL));
+
+	copy_page((void *)kto, (void *)kfrom);
+
+	raw_spin_unlock(&v6_lock);
+}
+
+/*
+ * Clear the user page.  We need to deal with the aliasing issues,
+ * so remap the kernel page into the same cache colour as the user
+ * page.
+ */
+static void v6_clear_user_highpage_aliasing(struct page *page, unsigned long vaddr)
+{
+	unsigned long to = COPYPAGE_V6_TO + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
+
+	/* FIXME: not highmem safe */
+	discard_old_kernel_data(page_address(page));
+
+	/*
+	 * Now clear the page using the same cache colour as
+	 * the pages ultimate destination.
+	 */
+	raw_spin_lock(&v6_lock);
+
+	set_top_pte(to, mk_pte(page, PAGE_KERNEL));
+	clear_page((void *)to);
+
+	raw_spin_unlock(&v6_lock);
+}
+
+struct cpu_user_fns v6_user_fns __initdata = {
+	.cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
+	.cpu_copy_user_highpage	= v6_copy_user_highpage_nonaliasing,
+};
+
+static int __init v6_userpage_init(void)
+{
+	if (cache_is_vipt_aliasing()) {
+		cpu_user.cpu_clear_user_highpage = v6_clear_user_highpage_aliasing;
+		cpu_user.cpu_copy_user_highpage = v6_copy_user_highpage_aliasing;
+	}
+
+	return 0;
+}
+
+core_initcall(v6_userpage_init);