Merge branch 'uaccess.csum' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull uaccess/csum updates from Al Viro:
 "Regularize the sitation with uaccess checksum primitives:

   - fold csum_partial_... into csum_and_copy_..._user()

   - on x86 collapse several access_ok()/stac()/clac() into
     user_access_begin()/user_access_end()"

* 'uaccess.csum' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  default csum_and_copy_to_user(): don't bother with access_ok()
  take the dummy csum_and_copy_from_user() into net/checksum.h
  arm: switch to csum_and_copy_from_user()
  sh32: convert to csum_and_copy_from_user()
  m68k: convert to csum_and_copy_from_user()
  xtensa: switch to providing csum_and_copy_from_user()
  sparc: switch to providing csum_and_copy_from_user()
  parisc: turn csum_partial_copy_from_user() into csum_and_copy_from_user()
  alpha: turn csum_partial_copy_from_user() into csum_and_copy_from_user()
  ia64: turn csum_partial_copy_from_user() into csum_and_copy_from_user()
  ia64: csum_partial_copy_nocheck(): don't abuse csum_partial_copy_from_user()
  x86: switch 32bit csum_and_copy_to_user() to user_access_{begin,end}()
  x86: switch both 32bit and 64bit to providing csum_and_copy_from_user()
  x86_64: csum_..._copy_..._user(): switch to unsafe_..._user()
  get rid of csum_partial_copy_to_user()

22 files changed, 84 insertions, 186 deletions

diff --git a/arch/alpha/include/asm/checksum.h b/arch/alpha/include/asm/checksum.h
index 473e6ccb65a3..0eac81624d01 100644
--- a/arch/alpha/include/asm/checksum.h
+++ b/arch/alpha/include/asm/checksum.h
@@ -41,7 +41,8 @@ extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  * here even more important to align src and dst on a 32-bit (or even
  * better 64-bit) boundary
  */
-__wsum csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *errp);
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
+__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *errp);
 
 __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
 
diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c
index e53f96e8aa6d..af1dad74e933 100644
--- a/arch/alpha/lib/csum_partial_copy.c
+++ b/arch/alpha/lib/csum_partial_copy.c
@@ -325,7 +325,7 @@ csum_partial_cfu_unaligned(const unsigned long __user * src,
 }
 
 __wsum
-csum_partial_copy_from_user(const void __user *src, void *dst, int len,
+csum_and_copy_from_user(const void __user *src, void *dst, int len,
 			       __wsum sum, int *errp)
 {
 	unsigned long checksum = (__force u32) sum;
@@ -369,7 +369,7 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 	}
 	return (__force __wsum)checksum;
 }
-EXPORT_SYMBOL(csum_partial_copy_from_user);
+EXPORT_SYMBOL(csum_and_copy_from_user);
 
 __wsum
 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
@@ -377,7 +377,7 @@ csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 	__wsum checksum;
 	mm_segment_t oldfs = get_fs();
 	set_fs(KERNEL_DS);
-	checksum = csum_partial_copy_from_user((__force const void __user *)src,
+	checksum = csum_and_copy_from_user((__force const void __user *)src,
 						dst, len, sum, NULL);
 	set_fs(oldfs);
 	return checksum;
diff --git a/arch/arm/include/asm/checksum.h b/arch/arm/include/asm/checksum.h
index 20043e0ebb07..ed6073fee338 100644
--- a/arch/arm/include/asm/checksum.h
+++ b/arch/arm/include/asm/checksum.h
@@ -40,6 +40,20 @@ csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum);
 __wsum
 csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr);
 
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
+static inline
+__wsum csum_and_copy_from_user (const void __user *src, void *dst,
+				      int len, __wsum sum, int *err_ptr)
+{
+	if (access_ok(src, len))
+		return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
+
+	if (len)
+		*err_ptr = -EFAULT;
+
+	return sum;
+}
+
 /*
  * 	Fold a partial checksum without adding pseudo headers
  */
diff --git a/arch/c6x/lib/checksum.c b/arch/c6x/lib/checksum.c
index 46940844c553..335ca4900808 100644
--- a/arch/c6x/lib/checksum.c
+++ b/arch/c6x/lib/checksum.c
@@ -4,28 +4,6 @@
 #include <linux/module.h>
 #include <net/checksum.h>
 
-#include <asm/byteorder.h>
-
-/*
- * copy from fs while checksumming, otherwise like csum_partial
- */
-__wsum
-csum_partial_copy_from_user(const void __user *src, void *dst, int len,
-			    __wsum sum, int *csum_err)
-{
-	int missing;
-
-	missing = __copy_from_user(dst, src, len);
-	if (missing) {
-		memset(dst + len - missing, 0, missing);
-		*csum_err = -EFAULT;
-	} else
-		*csum_err = 0;
-
-	return csum_partial(dst, len, sum);
-}
-EXPORT_SYMBOL(csum_partial_copy_from_user);
-
 /* These are from csum_64plus.S */
 EXPORT_SYMBOL(csum_partial);
 EXPORT_SYMBOL(csum_partial_copy);
diff --git a/arch/ia64/include/asm/checksum.h b/arch/ia64/include/asm/checksum.h
index 0ed18bc3f6cf..2a1c64629cdc 100644
--- a/arch/ia64/include/asm/checksum.h
+++ b/arch/ia64/include/asm/checksum.h
@@ -37,16 +37,6 @@ extern __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
  */
 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
 
-/*
- * Same as csum_partial, but copies from src while it checksums.
- *
- * Here it is even more important to align src and dst on a 32-bit (or
- * even better 64-bit) boundary.
- */
-extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
-						 int len, __wsum sum,
-						 int *errp);
-
 extern __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 					       int len, __wsum sum);
 
diff --git a/arch/ia64/lib/csum_partial_copy.c b/arch/ia64/lib/csum_partial_copy.c
index bf9396b1ed32..5d147a33d648 100644
--- a/arch/ia64/lib/csum_partial_copy.c
+++ b/arch/ia64/lib/csum_partial_copy.c
@@ -103,39 +103,11 @@ out:
  * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS.
  * But it's very tricky to get right even in C.
  */
-extern unsigned long do_csum(const unsigned char *, long);
-
-__wsum
-csum_partial_copy_from_user(const void __user *src, void *dst,
-				int len, __wsum psum, int *errp)
-{
-	unsigned long result;
-
-	/* XXX Fixme
-	 * for now we separate the copy from checksum for obvious
-	 * alignment difficulties. Look at the Alpha code and you'll be
-	 * scared.
-	 */
-
-	if (__copy_from_user(dst, src, len) != 0 && errp)
-		*errp = -EFAULT;
-
-	result = do_csum(dst, len);
-
-	/* add in old sum, and carry.. */
-	result += (__force u32)psum;
-	/* 32+c bits -> 32 bits */
-	result = (result & 0xffffffff) + (result >> 32);
-	return (__force __wsum)result;
-}
-
-EXPORT_SYMBOL(csum_partial_copy_from_user);
-
 __wsum
 csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 {
-	return csum_partial_copy_from_user((__force const void __user *)src,
-					   dst, len, sum, NULL);
+	memcpy(dst, src, len);
+	return csum_partial(dst, len, sum);
 }
 
 EXPORT_SYMBOL(csum_partial_copy_nocheck);
diff --git a/arch/m68k/include/asm/checksum.h b/arch/m68k/include/asm/checksum.h
index f9b94e4b94f9..3f2c15d6f18c 100644
--- a/arch/m68k/include/asm/checksum.h
+++ b/arch/m68k/include/asm/checksum.h
@@ -30,7 +30,8 @@ __wsum csum_partial(const void *buff, int len, __wsum sum);
  * better 64-bit) boundary
  */
 
-extern __wsum csum_partial_copy_from_user(const void __user *src,
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
+extern __wsum csum_and_copy_from_user(const void __user *src,
 						void *dst,
 						int len, __wsum sum,
 						int *csum_err);
diff --git a/arch/m68k/lib/checksum.c b/arch/m68k/lib/checksum.c
index 5fa3d392e181..31797be9a3dc 100644
--- a/arch/m68k/lib/checksum.c
+++ b/arch/m68k/lib/checksum.c
@@ -129,7 +129,7 @@ EXPORT_SYMBOL(csum_partial);
  */
 
 __wsum
-csum_partial_copy_from_user(const void __user *src, void *dst,
+csum_and_copy_from_user(const void __user *src, void *dst,
 			    int len, __wsum sum, int *csum_err)
 {
 	/*
@@ -316,7 +316,7 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 	return(sum);
 }
 
-EXPORT_SYMBOL(csum_partial_copy_from_user);
+EXPORT_SYMBOL(csum_and_copy_from_user);
 
 
 /*
diff --git a/arch/nios2/include/asm/checksum.h b/arch/nios2/include/asm/checksum.h
index 703c5ee63421..ec39698d3bea 100644
--- a/arch/nios2/include/asm/checksum.h
+++ b/arch/nios2/include/asm/checksum.h
@@ -14,8 +14,6 @@
 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
 extern __wsum csum_partial_copy(const void *src, void *dst, int len,
 				__wsum sum);
-extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
-					int len, __wsum sum, int *csum_err);
 #define csum_partial_copy_nocheck(src, dst, len, sum)	\
 	csum_partial_copy((src), (dst), (len), (sum))
 
diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h
index c1c22819a04d..fe8c63b2d2c3 100644
--- a/arch/parisc/include/asm/checksum.h
+++ b/arch/parisc/include/asm/checksum.h
@@ -27,13 +27,6 @@ extern __wsum csum_partial(const void *, int, __wsum);
 extern __wsum csum_partial_copy_nocheck(const void *, void *, int, __wsum);
 
 /*
- * this is a new version of the above that records errors it finds in *errp,
- * but continues and zeros the rest of the buffer.
- */
-extern __wsum csum_partial_copy_from_user(const void __user *src,
-		void *dst, int len, __wsum sum, int *errp);
-
-/*
  *	Optimized for IP headers, which always checksum on 4 octet boundaries.
  *
  *	Written by Randolph Chung <tausq@debian.org>, and then mucked with by
diff --git a/arch/parisc/lib/checksum.c b/arch/parisc/lib/checksum.c
index 256322c7b648..c6f161583549 100644
--- a/arch/parisc/lib/checksum.c
+++ b/arch/parisc/lib/checksum.c
@@ -123,23 +123,3 @@ __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return sum;
 }
 EXPORT_SYMBOL(csum_partial_copy_nocheck);
-
-/*
- * Copy from userspace and compute checksum.  If we catch an exception
- * then zero the rest of the buffer.
- */
-__wsum csum_partial_copy_from_user(const void __user *src,
-					void *dst, int len,
-					__wsum sum, int *err_ptr)
-{
-	int missing;
-
-	missing = copy_from_user(dst, src, len);
-	if (missing) {
-		memset(dst + len - missing, 0, missing);
-		*err_ptr = -EFAULT;
-	}
-		
-	return csum_partial(dst, len, sum);
-}
-EXPORT_SYMBOL(csum_partial_copy_from_user);
diff --git a/arch/s390/include/asm/checksum.h b/arch/s390/include/asm/checksum.h
index 91e376b0d28c..6d01c96aeb5c 100644
--- a/arch/s390/include/asm/checksum.h
+++ b/arch/s390/include/asm/checksum.h
@@ -39,25 +39,6 @@ csum_partial(const void *buff, int len, __wsum sum)
 	return sum;
 }
 
-/*
- * the same as csum_partial_copy, but copies from user space.
- *
- * here even more important to align src and dst on a 32-bit (or even
- * better 64-bit) boundary
- *
- * Copy from userspace and compute checksum.
- */
-static inline __wsum
-csum_partial_copy_from_user(const void __user *src, void *dst,
-                                          int len, __wsum sum,
-                                          int *err_ptr)
-{
-	if (unlikely(copy_from_user(dst, src, len)))
-		*err_ptr = -EFAULT;
-	return csum_partial(dst, len, sum);
-}
-
-
 static inline __wsum
 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
 {
diff --git a/arch/sh/include/asm/checksum_32.h b/arch/sh/include/asm/checksum_32.h
index 36b84cfd3f67..91571a42e44e 100644
--- a/arch/sh/include/asm/checksum_32.h
+++ b/arch/sh/include/asm/checksum_32.h
@@ -48,12 +48,17 @@ __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 }
 
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
-__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
+__wsum csum_and_copy_from_user(const void __user *src, void *dst,
 				   int len, __wsum sum, int *err_ptr)
 {
-	return csum_partial_copy_generic((__force const void *)src, dst,
+	if (access_ok(src, len))
+		return csum_partial_copy_generic((__force const void *)src, dst,
 					len, sum, err_ptr, NULL);
+	if (len)
+		*err_ptr = -EFAULT;
+	return sum;
 }
 
 /*
diff --git a/arch/sparc/include/asm/checksum.h b/arch/sparc/include/asm/checksum.h
index c3be56e2e768..a6256cb6fc5c 100644
--- a/arch/sparc/include/asm/checksum.h
+++ b/arch/sparc/include/asm/checksum.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef ___ASM_SPARC_CHECKSUM_H
 #define ___ASM_SPARC_CHECKSUM_H
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 #if defined(__sparc__) && defined(__arch64__)
 #include <asm/checksum_64.h>
 #else
diff --git a/arch/sparc/include/asm/checksum_32.h b/arch/sparc/include/asm/checksum_32.h
index 5fc98d80b03b..479a0b812af5 100644
--- a/arch/sparc/include/asm/checksum_32.h
+++ b/arch/sparc/include/asm/checksum_32.h
@@ -60,7 +60,7 @@ csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
 }
 
 static inline __wsum
-csum_partial_copy_from_user(const void __user *src, void *dst, int len,
+csum_and_copy_from_user(const void __user *src, void *dst, int len,
 			    __wsum sum, int *err)
   {
 	register unsigned long ret asm("o0") = (unsigned long)src;
@@ -68,6 +68,12 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 	register int l asm("g1") = len;
 	register __wsum s asm("g7") = sum;
 
+	if (unlikely(!access_ok(src, len))) {
+		if (len)
+			*err = -EFAULT;
+		return sum;
+	}
+
 	__asm__ __volatile__ (
 	".section __ex_table,#alloc\n\t"
 	".align 4\n\t"
@@ -83,8 +89,10 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
 	return (__force __wsum)ret;
 }
 
+#define HAVE_CSUM_COPY_USER
+
 static inline __wsum
-csum_partial_copy_to_user(const void *src, void __user *dst, int len,
+csum_and_copy_to_user(const void *src, void __user *dst, int len,
 			  __wsum sum, int *err)
 {
 	if (!access_ok(dst, len)) {
@@ -113,9 +121,6 @@ csum_partial_copy_to_user(const void *src, void __user *dst, int len,
 	}
 }
 
-#define HAVE_CSUM_COPY_USER
-#define csum_and_copy_to_user csum_partial_copy_to_user
-
 /* ihl is always 5 or greater, almost always is 5, and iph is word aligned
  * the majority of the time.
  */
diff --git a/arch/sparc/include/asm/checksum_64.h b/arch/sparc/include/asm/checksum_64.h
index e52450930e4e..0fa4433f5662 100644
--- a/arch/sparc/include/asm/checksum_64.h
+++ b/arch/sparc/include/asm/checksum_64.h
@@ -46,7 +46,7 @@ long __csum_partial_copy_from_user(const void __user *src,
 				   __wsum sum);
 
 static inline __wsum
-csum_partial_copy_from_user(const void __user *src,
+csum_and_copy_from_user(const void __user *src,
 			    void *dst, int len,
 			    __wsum sum, int *err)
 {
diff --git a/arch/x86/include/asm/checksum.h b/arch/x86/include/asm/checksum.h
index d79d1e622dcf..0ada98d5d09f 100644
--- a/arch/x86/include/asm/checksum.h
+++ b/arch/x86/include/asm/checksum.h
@@ -1,4 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#define  _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
+#define HAVE_CSUM_COPY_USER
 #ifdef CONFIG_X86_32
 # include <asm/checksum_32.h>
 #else
diff --git a/arch/x86/include/asm/checksum_32.h b/arch/x86/include/asm/checksum_32.h
index f57b94e02c57..11624c8a9d8d 100644
--- a/arch/x86/include/asm/checksum_32.h
+++ b/arch/x86/include/asm/checksum_32.h
@@ -44,18 +44,21 @@ static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 }
 
-static inline __wsum csum_partial_copy_from_user(const void __user *src,
-						 void *dst,
-						 int len, __wsum sum,
-						 int *err_ptr)
+static inline __wsum csum_and_copy_from_user(const void __user *src,
+					     void *dst, int len,
+					     __wsum sum, int *err_ptr)
 {
 	__wsum ret;
 
 	might_sleep();
-	stac();
+	if (!user_access_begin(src, len)) {
+		if (len)
+			*err_ptr = -EFAULT;
+		return sum;
+	}
 	ret = csum_partial_copy_generic((__force void *)src, dst,
 					len, sum, err_ptr, NULL);
-	clac();
+	user_access_end();
 
 	return ret;
 }
@@ -173,7 +176,6 @@ static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 /*
  *	Copy and checksum to user
  */
-#define HAVE_CSUM_COPY_USER
 static inline __wsum csum_and_copy_to_user(const void *src,
 					   void __user *dst,
 					   int len, __wsum sum,
@@ -182,11 +184,10 @@ static inline __wsum csum_and_copy_to_user(const void *src,
 	__wsum ret;
 
 	might_sleep();
-	if (access_ok(dst, len)) {
-		stac();
+	if (user_access_begin(dst, len)) {
 		ret = csum_partial_copy_generic(src, (__force void *)dst,
 						len, sum, NULL, err_ptr);
-		clac();
+		user_access_end();
 		return ret;
 	}
 
diff --git a/arch/x86/include/asm/checksum_64.h b/arch/x86/include/asm/checksum_64.h
index 3ec6d3267cf9..0a289b87e872 100644
--- a/arch/x86/include/asm/checksum_64.h
+++ b/arch/x86/include/asm/checksum_64.h
@@ -129,27 +129,19 @@ static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  */
 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
 
-#define  _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
-#define HAVE_CSUM_COPY_USER 1
-
-
 /* Do not call this directly. Use the wrappers below */
 extern __visible __wsum csum_partial_copy_generic(const void *src, const void *dst,
 					int len, __wsum sum,
 					int *src_err_ptr, int *dst_err_ptr);
 
 
-extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
+extern __wsum csum_and_copy_from_user(const void __user *src, void *dst,
 					  int len, __wsum isum, int *errp);
-extern __wsum csum_partial_copy_to_user(const void *src, void __user *dst,
+extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
 					int len, __wsum isum, int *errp);
 extern __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 					int len, __wsum sum);
 
-/* Old names. To be removed. */
-#define csum_and_copy_to_user csum_partial_copy_to_user
-#define csum_and_copy_from_user csum_partial_copy_from_user
-
 /**
  * ip_compute_csum - Compute an 16bit IP checksum.
  * @buff: buffer address.
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index c66c8b00f236..ee63d7576fd2 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -10,7 +10,7 @@
 #include <asm/smap.h>
 
 /**
- * csum_partial_copy_from_user - Copy and checksum from user space.
+ * csum_and_copy_from_user - Copy and checksum from user space.
  * @src: source address (user space)
  * @dst: destination address
  * @len: number of bytes to be copied.
@@ -21,13 +21,13 @@
  * src and dst are best aligned to 64bits.
  */
 __wsum
-csum_partial_copy_from_user(const void __user *src, void *dst,
+csum_and_copy_from_user(const void __user *src, void *dst,
 			    int len, __wsum isum, int *errp)
 {
 	might_sleep();
 	*errp = 0;
 
-	if (!likely(access_ok(src, len)))
+	if (!user_access_begin(src, len))
 		goto out_err;
 
 	/*
@@ -42,8 +42,7 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 		while (((unsigned long)src & 6) && len >= 2) {
 			__u16 val16;
 
-			if (__get_user(val16, (const __u16 __user *)src))
-				goto out_err;
+			unsafe_get_user(val16, (const __u16 __user *)src, out);
 
 			*(__u16 *)dst = val16;
 			isum = (__force __wsum)add32_with_carry(
@@ -53,25 +52,26 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 			len -= 2;
 		}
 	}
-	stac();
 	isum = csum_partial_copy_generic((__force const void *)src,
 				dst, len, isum, errp, NULL);
-	clac();
+	user_access_end();
 	if (unlikely(*errp))
 		goto out_err;
 
 	return isum;
 
+out:
+	user_access_end();
 out_err:
 	*errp = -EFAULT;
 	memset(dst, 0, len);
 
 	return isum;
 }
-EXPORT_SYMBOL(csum_partial_copy_from_user);
+EXPORT_SYMBOL(csum_and_copy_from_user);
 
 /**
- * csum_partial_copy_to_user - Copy and checksum to user space.
+ * csum_and_copy_to_user - Copy and checksum to user space.
  * @src: source address
  * @dst: destination address (user space)
  * @len: number of bytes to be copied.
@@ -82,14 +82,14 @@ EXPORT_SYMBOL(csum_partial_copy_from_user);
  * src and dst are best aligned to 64bits.
  */
 __wsum
-csum_partial_copy_to_user(const void *src, void __user *dst,
+csum_and_copy_to_user(const void *src, void __user *dst,
 			  int len, __wsum isum, int *errp)
 {
 	__wsum ret;
 
 	might_sleep();
 
-	if (unlikely(!access_ok(dst, len))) {
+	if (!user_access_begin(dst, len)) {
 		*errp = -EFAULT;
 		return 0;
 	}
@@ -100,9 +100,7 @@ csum_partial_copy_to_user(const void *src, void __user *dst,
 
 			isum = (__force __wsum)add32_with_carry(
 					(__force unsigned)isum, val16);
-			*errp = __put_user(val16, (__u16 __user *)dst);
-			if (*errp)
-				return isum;
+			unsafe_put_user(val16, (__u16 __user *)dst, out);
 			src += 2;
 			dst += 2;
 			len -= 2;
@@ -110,13 +108,16 @@ csum_partial_copy_to_user(const void *src, void __user *dst,
 	}
 
 	*errp = 0;
-	stac();
 	ret = csum_partial_copy_generic(src, (void __force *)dst,
 					len, isum, NULL, errp);
-	clac();
+	user_access_end();
 	return ret;
+out:
+	user_access_end();
+	*errp = -EFAULT;
+	return isum;
 }
-EXPORT_SYMBOL(csum_partial_copy_to_user);
+EXPORT_SYMBOL(csum_and_copy_to_user);
 
 /**
  * csum_partial_copy_nocheck - Copy and checksum.
diff --git a/arch/x86/um/asm/checksum.h b/arch/x86/um/asm/checksum.h
index 2a56cac64687..ff6bba2c8ab6 100644
--- a/arch/x86/um/asm/checksum.h
+++ b/arch/x86/um/asm/checksum.h
@@ -36,26 +36,6 @@ __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return csum_partial(dst, len, sum);
 }
 
-/*
- * the same as csum_partial, but copies from src while it
- * checksums, and handles user-space pointer exceptions correctly, when needed.
- *
- * here even more important to align src and dst on a 32-bit (or even
- * better 64-bit) boundary
- */
-
-static __inline__
-__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
-					 int len, __wsum sum, int *err_ptr)
-{
-	if (copy_from_user(dst, src, len)) {
-		*err_ptr = -EFAULT;
-		return (__force __wsum)-1;
-	}
-
-	return csum_partial(dst, len, sum);
-}
-
 /**
  * csum_fold - Fold and invert a 32bit checksum.
  * sum: 32bit unfolded sum
diff --git a/arch/xtensa/include/asm/checksum.h b/arch/xtensa/include/asm/checksum.h
index 8b687176ad72..d8292cc9ebdf 100644
--- a/arch/xtensa/include/asm/checksum.h
+++ b/arch/xtensa/include/asm/checksum.h
@@ -44,8 +44,6 @@ asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
 /*
  *	Note: when you get a NULL pointer exception here this means someone
  *	passed in an incorrect kernel address to one of these functions.
- *
- *	If you use these functions directly please don't forget the access_ok().
  */
 static inline
 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
@@ -54,12 +52,17 @@ __wsum csum_partial_copy_nocheck(const void *src, void *dst,
 	return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
 }
 
+#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 static inline
-__wsum csum_partial_copy_from_user(const void __user *src, void *dst,
+__wsum csum_and_copy_from_user(const void __user *src, void *dst,
 				   int len, __wsum sum, int *err_ptr)
 {
-	return csum_partial_copy_generic((__force const void *)src, dst,
+	if (access_ok(dst, len))
+		return csum_partial_copy_generic((__force const void *)src, dst,
 					len, sum, err_ptr, NULL);
+	if (len)
+		*err_ptr = -EFAULT;
+	return sum;
 }
 
 /*