From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40q5FT6MYzzF0fW for ; Mon, 21 May 2018 14:21:33 +1000 (AEST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w4L4J4DS047965 for ; Mon, 21 May 2018 00:21:31 -0400 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2j3jqk7e23-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 21 May 2018 00:21:31 -0400 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 21 May 2018 05:21:29 +0100 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 In-Reply-To: <20180521042108.8318-1-ravi.bangoria@linux.ibm.com> References: <20180521042108.8318-1-ravi.bangoria@linux.ibm.com> Message-Id: <20180521042108.8318-3-ravi.bangoria@linux.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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