From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755330AbdKAV5c (ORCPT ); Wed, 1 Nov 2017 17:57:32 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35050 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933636AbdKAVVX (ORCPT ); Wed, 1 Nov 2017 17:21:23 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: "Oliver O'Halloran" , Michael Ellerman , Willy Tarreau Subject: [PATCH 3.10 034/139] powerpc/asm: Mark cr0 as clobbered in mftb() Date: Wed, 1 Nov 2017 22:17:34 +0100 Message-Id: <1509571159-4405-35-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571159-4405-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oliver O'Halloran commit 2400fd822f467cb4c886c879d8ad99feac9cf319 upstream. The workaround for the CELL timebase bug does not correctly mark cr0 as being clobbered. This means GCC doesn't know that the asm block changes cr0 and might leave the result of an unrelated comparison in cr0 across the block, which we then trash, leading to basically random behaviour. Fixes: 859deea949c3 ("[POWERPC] Cell timebase bug workaround") Cc: stable@vger.kernel.org Signed-off-by: Oliver O'Halloran [mpe: Tweak change log and flag for stable] Signed-off-by: Michael Ellerman Signed-off-by: Willy Tarreau --- arch/powerpc/include/asm/reg.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 469d771..954168b 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1136,7 +1136,7 @@ " .llong 0\n" \ " .llong 0\n" \ ".previous" \ - : "=r" (rval) : "i" (CPU_FTR_CELL_TB_BUG)); rval;}) + : "=r" (rval) : "i" (CPU_FTR_CELL_TB_BUG) : "cr0"); rval;}) #else #define mftb() ({unsigned long rval; \ asm volatile("mftb %0" : "=r" (rval)); rval;}) -- 2.8.0.rc2.1.gbe9624a