kgdb: update mem2hex/hex2mem funcs

Convert the funcs to do the conversion inline so that we can do the copy
all at once with memcpy.  This let's us push out an weird arch-specific
issue with accessing different regions of memory to the memcpy function
like the MMRs on Blackfin systems, and it should be a bit faster.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

common/kgdb.c

@@ -132,11 +132,20 @@ hex(unsigned char ch)
 static unsigned char *
 mem2hex(char *mem, char *buf, int count)
 {
+	char *tmp;
 	unsigned char ch;
 
+	/*
+	 * We use the upper half of buf as an intermediate buffer for the
+	 * raw memory copy.  Hex conversion will work against this one.
+	 */
+	tmp = buf + count;
 	longjmp_on_fault = 1;
+
+	memcpy(tmp, mem, count);
+
 	while (count-- > 0) {
-		ch = *mem++;
+		ch = *tmp++;
 		*buf++ = hexchars[ch >> 4];
 		*buf++ = hexchars[ch & 0xf];
 	}
@@ -151,21 +160,33 @@ mem2hex(char *mem, char *buf, int count)
 static char *
 hex2mem(char *buf, char *mem, int count)
 {
-	int i, hexValue;
-	unsigned char ch;
-	char *mem_start = mem;
+	int hexValue;
+	char *tmp_raw, *tmp_hex;
+
+	/*
+	 * We use the upper half of buf as an intermediate buffer for the
+	 * raw memory that is converted from hex.
+	 */
+	tmp_raw = buf + count * 2;
+	tmp_hex = tmp_raw - 1;
 
 	longjmp_on_fault = 1;
-	for (i=0; i<count; i++) {
-		if ((hexValue = hex(*buf++)) < 0)
+	while (tmp_hex >= buf) {
+		tmp_raw--;
+		hexValue = hex(*tmp_hex--);
+		if (hexValue < 0)
 			kgdb_error(KGDBERR_NOTHEXDIG);
-		ch = hexValue << 4;
-		if ((hexValue = hex(*buf++)) < 0)
+		*tmp_raw = hexValue;
+		hexValue = hex(*tmp_hex--);
+		if (hexValue < 0)
 			kgdb_error(KGDBERR_NOTHEXDIG);
-		ch |= hexValue;
-		*mem++ = ch;
+		*tmp_raw |= hexValue << 4;
+
 	}
-	kgdb_flush_cache_range((void *)mem_start, (void *)(mem - 1));
+
+	memcpy(mem, tmp_raw, count);
+
+	kgdb_flush_cache_range((void *)mem, (void *)(mem+count));
 	longjmp_on_fault = 0;
 
 	return buf;