[v2,03/20] lib: move memmove()

Commit Message

Jan Beulich April 21, 2021, 2:19 p.m. UTC

By moving the function into an archive, x86 doesn't need to announce
anymore that is has its own implementation - symbol resolution by the
linker will now guarantee that the generic function remains unused, and
the forwarding to the compiler built-in gets done by the common header
anyway.

Allow the function to be individually linkable, discardable, and
overridable.

Signed-off-by: Jan Beulich <[e-mail]>

Patch

--- a/xen/common/string.c
+++ b/xen/common/string.c
@@ -311,36 +311,6 @@  char *(strstr)(const char *s1, const cha
 }
 #endif
 
-#ifndef __HAVE_ARCH_MEMMOVE
-/**
- * memmove - Copy one area of memory to another
- * @dest: Where to copy to
- * @src: Where to copy from
- * @count: The size of the area.
- *
- * Unlike memcpy(), memmove() copes with overlapping areas.
- */
-void *(memmove)(void *dest, const void *src, size_t count)
-{
-	char *tmp, *s;
-
-	if (dest <= src) {
-		tmp = (char *) dest;
-		s = (char *) src;
-		while (count--)
-			*tmp++ = *s++;
-		}
-	else {
-		tmp = (char *) dest + count;
-		s = (char *) src + count;
-		while (count--)
-			*--tmp = *--s;
-		}
-
-	return dest;
-}
-#endif
-
 #ifndef __HAVE_ARCH_MEMCMP
 /**
  * memcmp - Compare two areas of memory
--- a/xen/include/asm-x86/string.h
+++ b/xen/include/asm-x86/string.h
@@ -1,9 +1,6 @@ 
 #ifndef __X86_STRING_H__
 #define __X86_STRING_H__
 
-#define __HAVE_ARCH_MEMMOVE
-#define memmove(d, s, n) __builtin_memmove(d, s, n)
-
 #endif /* __X86_STRING_H__ */
 /*
  * Local variables:
--- a/xen/lib/Makefile
+++ b/xen/lib/Makefile
@@ -5,6 +5,7 @@  lib-y += ctors.o
 lib-y += ctype.o
 lib-y += list-sort.o
 lib-y += memcpy.o
+lib-y += memmove.o
 lib-y += memset.o
 lib-y += muldiv64.o
 lib-y += parse-size.o
--- /dev/null
+++ b/xen/lib/memmove.c
@@ -0,0 +1,42 @@ 
+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <xen/string.h>
+
+/**
+ * memmove - Copy one area of memory to another
+ * @dest: Where to copy to
+ * @src: Where to copy from
+ * @count: The size of the area.
+ *
+ * Unlike memcpy(), memmove() copes with overlapping areas.
+ */
+void *(memmove)(void *dest, const void *src, size_t count)
+{
+	char *tmp, *s;
+
+	if (dest <= src) {
+		tmp = (char *) dest;
+		s = (char *) src;
+		while (count--)
+			*tmp++ = *s++;
+	} else {
+		tmp = (char *) dest + count;
+		s = (char *) src + count;
+		while (count--)
+			*--tmp = *--s;
+	}
+
+	return dest;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: t
+ * End:
+ */