1 files changed, 92 insertions, 0 deletions
diff --git a/arch/arm/mm/copypage-v4wb.c b/arch/arm/mm/copypage-v4wb.c
new file mode 100644
index 000000000..c3581b226
--- /dev/null
+++ b/arch/arm/mm/copypage-v4wb.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/mm/copypage-v4wb.c
+ *
+ *  Copyright (C) 1995-1999 Russell King
+ */
+#include <linux/init.h>
+#include <linux/highmem.h>
+
+/*
+ * ARMv4 optimised copy_user_highpage
+ *
+ * We flush the destination cache lines just before we write the data into the
+ * corresponding address.  Since the Dcache is read-allocate, this removes the
+ * Dcache aliasing issue.  The writes will be forwarded to the write buffer,
+ * and merged as appropriate.
+ *
+ * Note: We rely on all ARMv4 processors implementing the "invalidate D line"
+ * instruction.  If your processor does not supply this, you have to write your
+ * own copy_user_highpage that does the right thing.
+ */
+static void v4wb_copy_user_page(void *kto, const void *kfrom)
+{
+	int tmp;
+
+	asm volatile ("\
+	.syntax unified\n\
+	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
+1:	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
+	ldmia	%1!, {r3, r4, ip, lr}		@ 4+1\n\
+	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
+	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
+	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
+	ldmia	%1!, {r3, r4, ip, lr}		@ 4\n\
+	subs	%2, %2, #1			@ 1\n\
+	stmia	%0!, {r3, r4, ip, lr}		@ 4\n\
+	ldmiane	%1!, {r3, r4, ip, lr}		@ 4\n\
+	bne	1b				@ 1\n\
+	mcr	p15, 0, %1, c7, c10, 4		@ 1   drain WB"
+	: "+&r" (kto), "+&r" (kfrom), "=&r" (tmp)
+	: "2" (PAGE_SIZE / 64)
+	: "r3", "r4", "ip", "lr");
+}
+
+void v4wb_copy_user_highpage(struct page *to, struct page *from,
+	unsigned long vaddr, struct vm_area_struct *vma)
+{
+	void *kto, *kfrom;
+
+	kto = kmap_atomic(to);
+	kfrom = kmap_atomic(from);
+	flush_cache_page(vma, vaddr, page_to_pfn(from));
+	v4wb_copy_user_page(kto, kfrom);
+	kunmap_atomic(kfrom);
+	kunmap_atomic(kto);
+}
+
+/*
+ * ARMv4 optimised clear_user_page
+ *
+ * Same story as above.
+ */
+void v4wb_clear_user_highpage(struct page *page, unsigned long vaddr)
+{
+	void *ptr, *kaddr = kmap_atomic(page);
+	asm volatile("\
+	mov	r1, %2				@ 1\n\
+	mov	r2, #0				@ 1\n\
+	mov	r3, #0				@ 1\n\
+	mov	ip, #0				@ 1\n\
+	mov	lr, #0				@ 1\n\
+1:	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	mcr	p15, 0, %0, c7, c6, 1		@ 1   invalidate D line\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	stmia	%0!, {r2, r3, ip, lr}		@ 4\n\
+	subs	r1, r1, #1			@ 1\n\
+	bne	1b				@ 1\n\
+	mcr	p15, 0, r1, c7, c10, 4		@ 1   drain WB"
+	: "=r" (ptr)
+	: "0" (kaddr), "I" (PAGE_SIZE / 64)
+	: "r1", "r2", "r3", "ip", "lr");
+	kunmap_atomic(kaddr);
+}
+
+struct cpu_user_fns v4wb_user_fns __initdata = {
+	.cpu_clear_user_highpage = v4wb_clear_user_highpage,
+	.cpu_copy_user_highpage	= v4wb_copy_user_highpage,
+};