From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20090318124844.895336869@de.ibm.com> References: <20090318124829.637003183@de.ibm.com> Date: Wed, 18 Mar 2009 13:48:30 +0100 From: Martin Schwidefsky Subject: [patch 1/6] __div64_31 broken for CONFIG_MARCH_G5 Content-Disposition: inline; filename=001-div64.diff Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Heiko Carstens , stable@kernel.org, Martin Schwidefsky List-ID: From: Martin Schwidefsky The implementation of __div64_31 for G5 machines is broken. The comments in __div64_31 are correct, only the code does not do what the comments say. The part "If the remainder has overflown subtract base and increase the quotient" is only partially realized, the base is subtracted correctly but the quotient is only increased if the dividend had the last bit set. Using the correct instruction fixes the problem. Cc: stable@kernel.org Reported-by: Frans Pop Tested-by: Frans Pop Signed-off-by: Martin Schwidefsky --- arch/s390/lib/div64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: quilt-2.6/arch/s390/lib/div64.c =================================================================== --- quilt-2.6.orig/arch/s390/lib/div64.c +++ quilt-2.6/arch/s390/lib/div64.c @@ -61,7 +61,7 @@ static uint32_t __div64_31(uint64_t *n, " clr %0,%3\n" " jl 0f\n" " slr %0,%3\n" - " alr %1,%2\n" + " ahi %1,1\n" "0:\n" : "+d" (reg2), "+d" (reg3), "=d" (tmp) : "d" (base), "2" (1UL) : "cc" ); -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.