From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44049 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753744AbcFEWYs (ORCPT ); Sun, 5 Jun 2016 18:24:48 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paul Burton , "Maciej W. Rozycki" , Aurelien Jarno , Adam Buchbinder , James Hogan , linux-mips@linux-mips.org, Ralf Baechle Subject: [PATCH 4.5 018/128] MIPS: Disable preemption during prctl(PR_SET_FP_MODE, ...) Date: Sun, 5 Jun 2016 15:22:53 -0700 Message-Id: <20160605222321.795537303@linuxfoundation.org> In-Reply-To: <20160605222321.183131188@linuxfoundation.org> References: <20160605222321.183131188@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Burton commit bd239f1e1429e7781096bf3884bdb1b2b1bb4f28 upstream. 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") Reviewed-by: Maciej W. Rozycki Tested-by: Aurelien Jarno Cc: Adam Buchbinder Cc: James Hogan Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/13144/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/process.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -601,6 +601,9 @@ int mips_set_process_fp_mode(struct task 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 /* Allow threads to use FP again */ atomic_set(&task->mm->context.fp_mode_switching, 0); + preempt_enable(); return 0; }