Merge branch 'uaccess' (batched user access infrastructure)

Expose an interface to allow users to mark several accesses together as
being user space accesses, allowing batching of the surrounding user
space access markers (SMAP on x86, PAN on arm64, domain register
switching on arm).

This is currently only used for the user string lenth and copying
functions, where the SMAP overhead on x86 drowned the actual user
accesses (only noticeable on newer microarchitectures that support SMAP
in the first place, of course).

* user access batching branch:
  Use the new batched user accesses in generic user string handling
  Add 'unsafe' user access functions for batched accesses
  x86: reorganize SMAP handling in user space accesses

lib/strncpy_from_user.c

@@ -39,7 +39,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
 		unsigned long c, data;
 
 		/* Fall back to byte-at-a-time if we get a page fault */
-		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
+		if (unlikely(unsafe_get_user(c,(unsigned long __user *)(src+res))))
 			break;
 		*(unsigned long *)(dst+res) = c;
 		if (has_zero(c, &data, &constants)) {
@@ -55,7 +55,7 @@ byte_at_a_time:
 	while (max) {
 		char c;
 
-		if (unlikely(__get_user(c,src+res)))
+		if (unlikely(unsafe_get_user(c,src+res)))
 			return -EFAULT;
 		dst[res] = c;
 		if (!c)
@@ -107,7 +107,12 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
 	src_addr = (unsigned long)src;
 	if (likely(src_addr < max_addr)) {
 		unsigned long max = max_addr - src_addr;
-		return do_strncpy_from_user(dst, src, count, max);
+		long retval;
+
+		user_access_begin();
+		retval = do_strncpy_from_user(dst, src, count, max);
+		user_access_end();
+		return retval;
 	}
 	return -EFAULT;
 }

lib/strnlen_user.c

@@ -45,7 +45,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
 	src -= align;
 	max += align;
 
-	if (unlikely(__get_user(c,(unsigned long __user *)src)))
+	if (unlikely(unsafe_get_user(c,(unsigned long __user *)src)))
 		return 0;
 	c |= aligned_byte_mask(align);
 
@@ -61,7 +61,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
 		if (unlikely(max <= sizeof(unsigned long)))
 			break;
 		max -= sizeof(unsigned long);
-		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
+		if (unlikely(unsafe_get_user(c,(unsigned long __user *)(src+res))))
 			return 0;
 	}
 	res -= align;
@@ -112,7 +112,12 @@ long strnlen_user(const char __user *str, long count)
 	src_addr = (unsigned long)str;
 	if (likely(src_addr < max_addr)) {
 		unsigned long max = max_addr - src_addr;
-		return do_strnlen_user(str, count, max);
+		long retval;
+
+		user_access_begin();
+		retval = do_strnlen_user(str, count, max);
+		user_access_end();
+		return retval;
 	}
 	return 0;
 }
@@ -141,7 +146,12 @@ long strlen_user(const char __user *str)
 	src_addr = (unsigned long)str;
 	if (likely(src_addr < max_addr)) {
 		unsigned long max = max_addr - src_addr;
-		return do_strnlen_user(str, ~0ul, max);
+		long retval;
+
+		user_access_begin();
+		retval = do_strnlen_user(str, ~0ul, max);
+		user_access_end();
+		return retval;
 	}
 	return 0;
 }