From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:45032 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751328AbbGaCOe (ORCPT ); Thu, 30 Jul 2015 22:14:34 -0400 From: Sasha Levin To: stable@vger.kernel.org, stable-commits@vger.kernel.org Cc: Martin Schwidefsky , Sasha Levin Subject: [added to the 3.18 stable tree] s390/sclp: clear upper register halves in _sclp_print_early Date: Thu, 30 Jul 2015 22:10:25 -0400 Message-Id: <1438308644-15635-25-git-send-email-sasha.levin@oracle.com> In-Reply-To: <1438308644-15635-1-git-send-email-sasha.levin@oracle.com> References: <1438308644-15635-1-git-send-email-sasha.levin@oracle.com> Sender: stable-owner@vger.kernel.org List-ID: From: Martin Schwidefsky This patch has been added to the 3.18 stable tree. If you have any objections, please let us know. =============== [ Upstream commit f9c87a6f46d508eae0d9ae640be98d50f237f827 ] If the kernel is compiled with gcc 5.1 and the XZ compression option the decompress_kernel function calls _sclp_print_early in 64-bit mode while the content of the upper register half of %r6 is non-zero. This causes a specification exception on the servc instruction in _sclp_servc. The _sclp_print_early function saves and restores the upper registers halves but it fails to clear them for the 31-bit code of the mini sclp driver. Cc: Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin --- arch/s390/kernel/sclp.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/s390/kernel/sclp.S b/arch/s390/kernel/sclp.S index a41f2c9..a0c4e76 100644 --- a/arch/s390/kernel/sclp.S +++ b/arch/s390/kernel/sclp.S @@ -277,6 +277,8 @@ ENTRY(_sclp_print_early) jno .Lesa2 ahi %r15,-80 stmh %r6,%r15,96(%r15) # store upper register halves + basr %r13,0 + lmh %r0,%r15,.Lzeroes-.(%r13) # clear upper register halves .Lesa2: #endif lr %r10,%r2 # save string pointer @@ -300,6 +302,8 @@ ENTRY(_sclp_print_early) #endif lm %r6,%r15,120(%r15) # restore registers br %r14 +.Lzeroes: + .fill 64,4,0 .LwritedataS4: .long 0x00760005 # SCLP command for write data -- 2.1.4