v4.19.13 snapshot.
diff --git a/arch/arm/lib/csumpartialcopyuser.S b/arch/arm/lib/csumpartialcopyuser.S
new file mode 100644
index 0000000..b83fdc0
--- /dev/null
+++ b/arch/arm/lib/csumpartialcopyuser.S
@@ -0,0 +1,101 @@
+/*
+ * linux/arch/arm/lib/csumpartialcopyuser.S
+ *
+ * Copyright (C) 1995-1998 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.
+ *
+ * 27/03/03 Ian Molton Clean up CONFIG_CPU
+ *
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/errno.h>
+#include <asm/asm-offsets.h>
+
+ .text
+
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+ .macro save_regs
+ mrc p15, 0, ip, c3, c0, 0
+ stmfd sp!, {r1, r2, r4 - r8, ip, lr}
+ uaccess_enable ip
+ .endm
+
+ .macro load_regs
+ ldmfd sp!, {r1, r2, r4 - r8, ip, lr}
+ mcr p15, 0, ip, c3, c0, 0
+ ret lr
+ .endm
+#else
+ .macro save_regs
+ stmfd sp!, {r1, r2, r4 - r8, lr}
+ .endm
+
+ .macro load_regs
+ ldmfd sp!, {r1, r2, r4 - r8, pc}
+ .endm
+#endif
+
+ .macro load1b, reg1
+ ldrusr \reg1, r0, 1
+ .endm
+
+ .macro load2b, reg1, reg2
+ ldrusr \reg1, r0, 1
+ ldrusr \reg2, r0, 1
+ .endm
+
+ .macro load1l, reg1
+ ldrusr \reg1, r0, 4
+ .endm
+
+ .macro load2l, reg1, reg2
+ ldrusr \reg1, r0, 4
+ ldrusr \reg2, r0, 4
+ .endm
+
+ .macro load4l, reg1, reg2, reg3, reg4
+ ldrusr \reg1, r0, 4
+ ldrusr \reg2, r0, 4
+ ldrusr \reg3, r0, 4
+ ldrusr \reg4, r0, 4
+ .endm
+
+/*
+ * unsigned int
+ * csum_partial_copy_from_user(const char *src, char *dst, int len, int sum, int *err_ptr)
+ * r0 = src, r1 = dst, r2 = len, r3 = sum, [sp] = *err_ptr
+ * Returns : r0 = checksum, [[sp, #0], #0] = 0 or -EFAULT
+ */
+
+#define FN_ENTRY ENTRY(csum_partial_copy_from_user)
+#define FN_EXIT ENDPROC(csum_partial_copy_from_user)
+
+#include "csumpartialcopygeneric.S"
+
+/*
+ * FIXME: minor buglet here
+ * We don't return the checksum for the data present in the buffer. To do
+ * so properly, we would have to add in whatever registers were loaded before
+ * the fault, which, with the current asm above is not predictable.
+ */
+ .pushsection .text.fixup,"ax"
+ .align 4
+9001: mov r4, #-EFAULT
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+ ldr r5, [sp, #9*4] @ *err_ptr
+#else
+ ldr r5, [sp, #8*4] @ *err_ptr
+#endif
+ str r4, [r5]
+ ldmia sp, {r1, r2} @ retrieve dst, len
+ add r2, r2, r1
+ mov r0, #0 @ zero the buffer
+9002: teq r2, r1
+ strneb r0, [r1], #1
+ bne 9002b
+ load_regs
+ .popsection