Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752582AbdGYVEt (ORCPT ); Tue, 25 Jul 2017 17:04:49 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33288 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752262AbdGYTUS (ORCPT ); Tue, 25 Jul 2017 15:20:18 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Oliver OHalloran , Michael Ellerman Subject: [PATCH 4.4 30/83] powerpc/asm: Mark cr0 as clobbered in mftb() Date: Tue, 25 Jul 2017 12:18:54 -0700 Message-Id: <20170725191712.921447298@linuxfoundation.org> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170725191708.449126292@linuxfoundation.org> References: <20170725191708.449126292@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1235 Lines: 35 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ 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") Signed-off-by: Oliver O'Halloran [mpe: Tweak change log and flag for stable] Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/reg.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1236,7 +1236,7 @@ static inline unsigned long mfvtb (void) " .llong 0\n" \ ".previous" \ : "=r" (rval) \ - : "i" (CPU_FTR_CELL_TB_BUG), "i" (SPRN_TBRL)); \ + : "i" (CPU_FTR_CELL_TB_BUG), "i" (SPRN_TBRL) : "cr0"); \ rval;}) #else #define mftb() ({unsigned long rval; \