MIPS: Avoid a BUG warning during prctl(PR_SET_FP_MODE, ...)

cpu_has_fpu macro uses smp_processor_id() and is currently executed
with preemption enabled, that triggers the warning at runtime.

It is assumed throughout the kernel that if any CPU has an FPU, then all
CPUs would have an FPU as well, so it is safe to perform the check with
preemption enabled - change the code to use raw_ variant of the check to
avoid the warning.

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org  # 4.0+
Patchwork: https://patchwork.linux-mips.org/patch/14125/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Author: MJNowakowski

arch/mips/kernel/process.c

@@ -605,14 +605,14 @@ int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 		return -EOPNOTSUPP;
 
 	/* Avoid inadvertently triggering emulation */
-	if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
-	    !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
+	if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
+	    !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 		return -EOPNOTSUPP;
-	if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
+	if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 		return -EOPNOTSUPP;
 
 	/* FR = 0 not supported in MIPS R6 */
-	if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
+	if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 		return -EOPNOTSUPP;
 
 	/* Proceed with the mode switch */