1 files changed, 26 insertions, 22 deletions

diff --git a/arch/arm/lib/csumpartialcopyuser.S b/arch/arm/lib/csumpartialcopyuser.S
index 1712f132b80d..c289bde04743 100644
--- a/arch/arm/lib/csumpartialcopyuser.S
+++ b/arch/arm/lib/csumpartialcopyuser.S
@@ -1,14 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *  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>
@@ -17,7 +13,8 @@
 
 		.text
 
-#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+#if defined(CONFIG_CPU_SW_DOMAIN_PAN)
+
 		.macro	save_regs
 		mrc	p15, 0, ip, c3, c0, 0
 		stmfd	sp!, {r1, r2, r4 - r8, ip, lr}
@@ -29,7 +26,23 @@
 		mcr	p15, 0, ip, c3, c0, 0
 		ret	lr
 		.endm
+
+#elif defined(CONFIG_CPU_TTBR0_PAN)
+
+		.macro	save_regs
+		mrc	p15, 0, ip, c2, c0, 2		@ read TTBCR
+		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, c2, c0, 2		@ restore TTBCR
+		ret	lr
+		.endm
+
 #else
+
 		.macro	save_regs
 		stmfd	sp!, {r1, r2, r4 - r8, lr}
 		.endm
@@ -37,6 +50,7 @@
 		.macro	load_regs
 		ldmfd	sp!, {r1, r2, r4 - r8, pc}
 		.endm
+
 #endif
 
 		.macro	load1b,	reg1
@@ -66,9 +80,9 @@
 
 /*
  * 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
+ * csum_partial_copy_from_user(const char *src, char *dst, int len)
+ *  r0 = src, r1 = dst, r2 = len
+ *  Returns : r0 = checksum or 0
  */
 
 #define FN_ENTRY	ENTRY(csum_partial_copy_from_user)
@@ -77,21 +91,11 @@
 #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.
+ * We report fault by returning 0 csum - impossible in normal case, since
+ * we start with 0xffffffff for initial sum.
  */
 		.pushsection .text.fixup,"ax"
 		.align	4
-9001:		mov	r4, #-EFAULT
-		ldr	r5, [sp, #8*4]		@ *err_ptr
-		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
+9001:		mov	r0, #0
 		load_regs
 		.popsection