From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751160AbeEUEVz (ORCPT ); Mon, 21 May 2018 00:21:55 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60644 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751050AbeEUEVb (ORCPT ); Mon, 21 May 2018 00:21:31 -0400 From: Ravi Bangoria To: mpe@ellerman.id.au, mikey@neuling.org Cc: benh@kernel.crashing.org, paulus@samba.org, naveen.n.rao@linux.vnet.ibm.com, matthew.brown.dev@gmail.com, cyrilbur@gmail.com, anton@samba.org, sandipan@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Ravi Bangoria Subject: [PATCH 2/3] powerpc/sstep: Fix kernel crash if VSX is not present Date: Mon, 21 May 2018 09:51:07 +0530 X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180521042108.8318-1-ravi.bangoria@linux.ibm.com> References: <20180521042108.8318-1-ravi.bangoria@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18052104-0008-0000-0000-000004F8A56F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18052104-0009-0000-0000-00001E8D2B40 Message-Id: <20180521042108.8318-3-ravi.bangoria@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-21_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805210051 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org emulate_step() is not checking runtime VSX feature flag before emulating an instruction. This is causing kernel crash when kernel is compiled with CONFIG_VSX=y but running on a machine where VSX is not supported or disabled. Ex, while running emulate_step tests on P6 machine: Oops: Exception in kernel mode, sig: 4 [#1] NIP [c000000000095c24] .load_vsrn+0x28/0x54 LR [c000000000094bdc] .emulate_loadstore+0x167c/0x17b0 Call Trace: 0x40fe240c7ae147ae (unreliable) .emulate_loadstore+0x167c/0x17b0 .emulate_step+0x25c/0x5bc .test_lxvd2x_stxvd2x+0x64/0x154 .test_emulate_step+0x38/0x4c .do_one_initcall+0x5c/0x2c0 .kernel_init_freeable+0x314/0x4cc .kernel_init+0x24/0x160 .ret_from_kernel_thread+0x58/0xb4 With fix: emulate_step_test: lxvd2x : FAIL emulate_step_test: stxvd2x : FAIL Fixes: https://github.com/linuxppc/linux/issues/148 Reported-by: Michael Ellerman Signed-off-by: Ravi Bangoria --- arch/powerpc/lib/sstep.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index db6bba259d91..23b7ddf04521 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -2544,6 +2544,15 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, #endif /* __powerpc64__ */ } + +#ifdef CONFIG_VSX + if ((GETTYPE(op->type) == LOAD_VSX || + GETTYPE(op->type) == STORE_VSX) && + !cpu_has_feature(CPU_FTR_VSX)) { + return -1; + } +#endif /* CONFIG_VSX */ + return 0; logical_done: -- 2.16.2