Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752656AbcDULob (ORCPT ); Thu, 21 Apr 2016 07:44:31 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:11374 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752604AbcDULoa (ORCPT ); Thu, 21 Apr 2016 07:44:30 -0400 From: Paul Burton To: , Ralf Baechle CC: Paul Burton , "stable # v4 . 0+" , Adam Buchbinder , , James Hogan Subject: [PATCH 1/2] MIPS: Disable preemption during prctl(PR_SET_FP_MODE, ...) Date: Thu, 21 Apr 2016 12:43:57 +0100 Message-ID: <1461239038-19991-1-git-send-email-paul.burton@imgtec.com> X-Mailer: git-send-email 2.8.0 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.100.200.79] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1260 Lines: 37 Whilst a PR_SET_FP_MODE prctl is performed there are decisions made based upon whether the task is executing on the current CPU. This may change if we're preempted, so disable preemption to avoid such changes for the lifetime of the mode switch. Signed-off-by: Paul Burton Fixes: 9791554b45a2 ("MIPS,prctl: add PR_[GS]ET_FP_MODE prctl options for MIPS") Cc: stable # v4.0+ --- arch/mips/kernel/process.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 92880ce..ce55ea0 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -601,6 +601,9 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value) if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6) return -EOPNOTSUPP; + /* Proceed with the mode switch */ + preempt_disable(); + /* Save FP & vector context, then disable FPU & MSA */ if (task->signal == current->signal) lose_fpu(1); @@ -659,6 +662,7 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value) /* Allow threads to use FP again */ atomic_set(&task->mm->context.fp_mode_switching, 0); + preempt_enable(); return 0; } -- 2.8.0