diff --git a/include/linux/string.h b/include/linux/string.h
index 4a5a0eb..b6ccdc2 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -31,6 +31,10 @@
 #ifndef __HAVE_ARCH_STRSCPY
 ssize_t strscpy(char *, const char *, size_t);
 #endif
+
+/* Wraps calls to strscpy()/memset(), no arch specific code required */
+ssize_t strscpy_pad(char *dest, const char *src, size_t count);
+
 #ifndef __HAVE_ARCH_STRCAT
 extern char * strcat(char *, const char *);
 #endif
@@ -131,6 +135,13 @@
 		return memset64((uint64_t *)p, (uintptr_t)v, n);
 }
 
+extern void **__memcat_p(void **a, void **b);
+#define memcat_p(a, b) ({					\
+	BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)),		\
+			 "type mismatch in memcat_p()");	\
+	(typeof(*a) *)__memcat_p((void **)(a), (void **)(b));	\
+})
+
 #ifndef __HAVE_ARCH_MEMCPY
 extern void * memcpy(void *,const void *,__kernel_size_t);
 #endif
@@ -143,6 +154,9 @@
 #ifndef __HAVE_ARCH_MEMCMP
 extern int memcmp(const void *,const void *,__kernel_size_t);
 #endif
+#ifndef __HAVE_ARCH_BCMP
+extern int bcmp(const void *,const void *,__kernel_size_t);
+#endif
 #ifndef __HAVE_ARCH_MEMCHR
 extern void * memchr(const void *,int,__kernel_size_t);
 #endif
@@ -213,7 +227,26 @@
 }
 
 size_t memweight(const void *ptr, size_t bytes);
-void memzero_explicit(void *s, size_t count);
+
+/**
+ * memzero_explicit - Fill a region of memory (e.g. sensitive
+ *		      keying data) with 0s.
+ * @s: Pointer to the start of the area.
+ * @count: The size of the area.
+ *
+ * Note: usually using memset() is just fine (!), but in cases
+ * where clearing out _local_ data at the end of a scope is
+ * necessary, memzero_explicit() should be used instead in
+ * order to prevent the compiler from optimising away zeroing.
+ *
+ * memzero_explicit() doesn't need an arch-specific version as
+ * it just invokes the one of memset() implicitly.
+ */
+static inline void memzero_explicit(void *s, size_t count)
+{
+	memset(s, 0, count);
+	barrier_data(s);
+}
 
 /**
  * kbasename - return the last part of a pathname.
@@ -449,4 +482,25 @@
 		memcpy(dest, src, dest_len);
 }
 
+/**
+ * str_has_prefix - Test if a string has a given prefix
+ * @str: The string to test
+ * @prefix: The string to see if @str starts with
+ *
+ * A common way to test a prefix of a string is to do:
+ *  strncmp(str, prefix, sizeof(prefix) - 1)
+ *
+ * But this can lead to bugs due to typos, or if prefix is a pointer
+ * and not a constant. Instead use str_has_prefix().
+ *
+ * Returns:
+ * * strlen(@prefix) if @str starts with @prefix
+ * * 0 if @str does not start with @prefix
+ */
+static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
+{
+	size_t len = strlen(prefix);
+	return strncmp(str, prefix, len) == 0 ? len : 0;
+}
+
 #endif /* _LINUX_STRING_H_ */