CHERI: make mem{cpy,move}(9) CHERI compatible

- Use intptr_t in place of long as the word type in the core copying
  loop where aligned words a copied.  This preserved the provenance of
  any copied pointers.
- When working with the address of src or dst use ptraddr_t rather than
  uintptr_t.  This avoid ambigious provenance in expressions involving
  multiple addresses.

As a minor tweak, rename the function to memmove since that is the
interface it implements (overlapping src and dst are permitted) and make
memcpy the alias rather than the other way around.

Reviewed by:	kib, markj
Effort:		CHERI upstreaming
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D57965

sys/libkern/bcopy.c

@@ -35,7 +35,9 @@
 #include <sys/param.h>
 #ifdef _KERNEL
 #include <sys/systm.h>
+#include <sys/stddef.h>
 #else
+#include <stddef.h>
 #include <string.h>
 #endif
 
@@ -46,7 +48,7 @@
  * sizeof(word) MUST BE A POWER OF TWO
  * SO THAT wmask BELOW IS ALL ONES
  */
-typedef	long	word;		/* "word" used for optimal copy speed */
+typedef	intptr_t word;		/* "word" used for optimal copy speed */
 
 #define	wsize	sizeof(word)
 #define wmask	(wsize - 1)
@@ -57,7 +59,7 @@ typedef	long	word;		/* "word" used for optimal copy speed */
  * (the portable versions of) bcopy, memcpy, and memmove.
  */
 void *
-memcpy(void *dst0, const void *src0, size_t length)
+memmove(void *dst0, const void *src0, size_t length)
 {
 	char		*dst;
 	const char	*src;
@@ -76,18 +78,18 @@ memcpy(void *dst0, const void *src0, size_t length)
 #define	TLOOP(s) if (t) TLOOP1(s)
 #define	TLOOP1(s) do { s; } while (--t)
 
-	if ((unsigned long)dst < (unsigned long)src) {
+	if ((ptraddr_t)dst < (ptraddr_t)src) {
 		/*
 		 * Copy forward.
 		 */
 		t = (size_t)src;	/* only need low bits */
 
-		if ((t | (uintptr_t)dst) & wmask) {
+		if ((t | (ptraddr_t)dst) & wmask) {
 			/*
 			 * Try to align operands.  This cannot be done
 			 * unless the low bits match.
 			 */
-			if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
+			if ((t ^ (ptraddr_t)dst) & wmask || length < wsize) {
 				t = length;
 			} else {
 				t = wsize - (t & wmask);
@@ -112,10 +114,10 @@ memcpy(void *dst0, const void *src0, size_t length)
 		 */
 		src += length;
 		dst += length;
-		t = (uintptr_t)src;
+		t = (size_t)src;
 
-		if ((t | (uintptr_t)dst) & wmask) {
-			if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
+		if ((t | (ptraddr_t)dst) & wmask) {
+			if ((t ^ (ptraddr_t)dst) & wmask || length <= wsize) {
 				t = length;
 			} else {
 				t &= wmask;
@@ -134,4 +136,4 @@ done:
 	return (dst0);
 }
 
-__strong_reference(memcpy, memmove);
+__strong_reference(memmove, memcpy);