[PATCH] print negative numbers correctly via vsprintf in arch/ppc64/boot/prom.c

[Olaf Hering]

 On Sun, May 08, Olaf Hering wrote:

> 
> remove unused arch/ppc64/boot/div64.S, it is built but not called

The other way round:

if num has a value of -1, accessing the digits[] array will fail and the
format string will be printed in funny way, or not at all.
This happens if one prints negative numbers.
Just change the code to match lib/vsprintf.c
asm/div64.h cant be used because u64 maps to u32 for this build.
uint64_t -> __u64 -> unsigned long

Signed-off-by: Olaf Hering <olh at suse.de>

Index: linux-2.6.12-rc4-olh/arch/ppc64/boot/prom.c
===================================================================
--- linux-2.6.12-rc4-olh.orig/arch/ppc64/boot/prom.c
+++ linux-2.6.12-rc4-olh/arch/ppc64/boot/prom.c
@@ -11,6 +11,23 @@
 #include <linux/string.h>
 #include <linux/ctype.h>
 
+extern __u32 __div64_32(unsigned long long *dividend, __u32 divisor);
+
+/* The unnecessary pointer compare is there
+ * to check for type safety (n must be 64bit)
+ */
+# define do_div(n,base) ({				\
+	__u32 __base = (base);			\
+	__u32 __rem;					\
+	(void)(((typeof((n)) *)0) == ((unsigned long long *)0));	\
+	if (((n) >> 32) == 0) {			\
+		__rem = (__u32)(n) % __base;		\
+		(n) = (__u32)(n) / __base;		\
+	} else 						\
+		__rem = __div64_32(&(n), __base);	\
+	__rem;						\
+ })
+
 int (*prom)(void *);
 
 void *chosen_handle;
@@ -352,7 +369,7 @@ static int skip_atoi(const char **s)
 #define SPECIAL	32		/* 0x */
 #define LARGE	64		/* use 'ABCDEF' instead of 'abcdef' */
 
-static char * number(char * str, long num, int base, int size, int precision, int type)
+static char * number(char * str, unsigned long long num, int base, int size, int precision, int type)
 {
 	char c,sign,tmp[66];
 	const char *digits="0123456789abcdefghijklmnopqrstuvwxyz";
@@ -367,9 +384,9 @@ static char * number(char * str, long nu
 	c = (type & ZEROPAD) ? '0' : ' ';
 	sign = 0;
 	if (type & SIGN) {
-		if (num < 0) {
+		if ((signed long long)num < 0) {
 			sign = '-';
-			num = -num;
+			num = - (unsigned long long)num;
 			size--;
 		} else if (type & PLUS) {
 			sign = '+';
@@ -389,8 +406,7 @@ static char * number(char * str, long nu
 	if (num == 0)
 		tmp[i++]='0';
 	else while (num != 0) {
-		tmp[i++] = digits[num % base];
-		num /= base;
+		tmp[i++] = digits[do_div(num, base)];
 	}
 	if (i > precision)
 		precision = i;
@@ -426,7 +442,7 @@ int sprintf(char * buf, const char *fmt,
 int vsprintf(char *buf, const char *fmt, va_list args)
 {
 	int len;
-	unsigned long num;
+	unsigned long long num;
 	int i, base;
 	char * str;
 	const char *s;