powerpc: Fix a corner case in __div64_32

The code was incorrectly doing a division by 0 in the case where
the denominator was 0x100000000 and the divisor was 0xffffffff.
Thanks to Fred Liu of Motorola for pointing this out.

Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/lib/div64.S b/arch/powerpc/lib/div64.S
index 3527569e992685e728c3e9e6902e6ec06a2e4145..83d9832fd919c3ab02bb91fea3b19fe828cbddc1 100644 (file)
--- a/arch/powerpc/lib/div64.S
+++ b/arch/powerpc/lib/div64.S
@@ -33,9 +33,10 @@ _GLOBAL(__div64_32)
        cntlzw  r0,r5           # we are shifting the dividend right
        li      r10,-1          # to make it < 2^32, and shifting
        srw     r10,r10,r0      # the divisor right the same amount,
-       add     r9,r4,r10       # rounding up (so the estimate cannot
+       addc    r9,r4,r10       # rounding up (so the estimate cannot
        andc    r11,r6,r10      # ever be too large, only too small)
        andc    r9,r9,r10
+       addze   r9,r9
        or      r11,r5,r11
        rotlw   r9,r9,r0
        rotlw   r11,r11,r0