x86: switch both 32bit and 64bit to providing csum_and_copy_from_user()

... rather than messing with the wrapper.  As a side effect,
32bit variant gets access_ok() into it and can be switched to
user_access_begin()/user_access_end()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/x86/include/asm/checksum.h

 /* SPDX-License-Identifier: GPL-2.0 */
+#define  _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
 #ifdef CONFIG_X86_32
 # include <asm/checksum_32.h>
 #else

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;
 }

arch/x86/include/asm/checksum_64.h

@@ -129,7 +129,6 @@ 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
 
 
@@ -139,15 +138,13 @@ extern __visible __wsum csum_partial_copy_generic(const void *src, const void *d
 					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_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);
 
-#define csum_and_copy_from_user csum_partial_copy_from_user
-
 /**
  * ip_compute_csum - Compute an 16bit IP checksum.
  * @buff: buffer address.

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.
@@ -21,7 +21,7 @@
  * 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();
@@ -68,7 +68,7 @@ csum_partial_copy_from_user(const void __user *src, void *dst,
 
 	return isum;
 }
-EXPORT_SYMBOL(csum_partial_copy_from_user);
+EXPORT_SYMBOL(csum_and_copy_from_user);
 
 /**
  * csum_and_copy_to_user - Copy and checksum to user space.