From bd239f1e1429e7781096bf3884bdb1b2b1bb4f28 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Thu, 21 Apr 2016 12:43:57 +0100 Subject: [PATCH] MIPS: Disable preemption during prctl(PR_SET_FP_MODE, ...) 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: stable # v4.0+ 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 --- 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 f57891616357..dcccc6dc68e6 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -597,6 +597,9 @@ 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); @@ -655,6 +658,7 @@ 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; } -- 2.20.1