v4.19.13 snapshot.
diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
new file mode 100644
index 0000000..0224416
--- /dev/null
+++ b/arch/arm/mm/copypage-v4mc.c
@@ -0,0 +1,115 @@
+/*
+ * linux/arch/arm/lib/copypage-armv4mc.S
+ *
+ * Copyright (C) 1995-2005 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This handles the mini data cache, as found on SA11x0 and XScale
+ * processors. When we copy a user page page, we map it in such a way
+ * that accesses to this page will not touch the main data cache, but
+ * will be cached in the mini data cache. This prevents us thrashing
+ * the main data cache on page faults.
+ */
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
+
+#include "mm.h"
+
+#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
+ L_PTE_MT_MINICACHE)
+
+static DEFINE_RAW_SPINLOCK(minicache_lock);
+
+/*
+ * ARMv4 mini-dcache 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 __naked
+mc_copy_user_page(void *from, void *to)
+{
+ asm volatile(
+ "stmfd sp!, {r4, lr} @ 2\n\
+ mov r4, %2 @ 1\n\
+ ldmia %0!, {r2, r3, ip, lr} @ 4\n\
+1: mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
+ stmia %1!, {r2, r3, ip, lr} @ 4\n\
+ ldmia %0!, {r2, r3, ip, lr} @ 4+1\n\
+ stmia %1!, {r2, r3, ip, lr} @ 4\n\
+ ldmia %0!, {r2, r3, ip, lr} @ 4\n\
+ mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
+ stmia %1!, {r2, r3, ip, lr} @ 4\n\
+ ldmia %0!, {r2, r3, ip, lr} @ 4\n\
+ subs r4, r4, #1 @ 1\n\
+ stmia %1!, {r2, r3, ip, lr} @ 4\n\
+ ldmneia %0!, {r2, r3, ip, lr} @ 4\n\
+ bne 1b @ 1\n\
+ ldmfd sp!, {r4, pc} @ 3"
+ :
+ : "r" (from), "r" (to), "I" (PAGE_SIZE / 64));
+}
+
+void v4_mc_copy_user_highpage(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma)
+{
+ void *kto = kmap_atomic(to);
+
+ if (!test_and_set_bit(PG_dcache_clean, &from->flags))
+ __flush_dcache_page(page_mapping_file(from), from);
+
+ raw_spin_lock(&minicache_lock);
+
+ set_top_pte(COPYPAGE_MINICACHE, mk_pte(from, minicache_pgprot));
+
+ mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
+
+ raw_spin_unlock(&minicache_lock);
+
+ kunmap_atomic(kto);
+}
+
+/*
+ * ARMv4 optimised clear_user_page
+ */
+void v4_mc_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"
+ : "=r" (ptr)
+ : "0" (kaddr), "I" (PAGE_SIZE / 64)
+ : "r1", "r2", "r3", "ip", "lr");
+ kunmap_atomic(kaddr);
+}
+
+struct cpu_user_fns v4_mc_user_fns __initdata = {
+ .cpu_clear_user_highpage = v4_mc_clear_user_highpage,
+ .cpu_copy_user_highpage = v4_mc_copy_user_highpage,
+};