MIPS: Avoid an FPE exception in FCSR mask probing

Use the default FCSR value in mask probing, avoiding an FPE exception
where reset has left any exception enable and their corresponding cause
bits set and the register is then rewritten with these bits active.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index e36515d..209e5b7 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -74,13 +74,12 @@
 {
 	unsigned long sr, mask, fcsr, fcsr0, fcsr1;
 
+	fcsr = c->fpu_csr31;
 	mask = FPU_CSR_ALL_X | FPU_CSR_ALL_E | FPU_CSR_ALL_S | FPU_CSR_RM;
 
 	sr = read_c0_status();
 	__enable_fpu(FPU_AS_IS);
 
-	fcsr = read_32bit_cp1_register(CP1_STATUS);
-
 	fcsr0 = fcsr & mask;
 	write_32bit_cp1_register(CP1_STATUS, fcsr0);
 	fcsr0 = read_32bit_cp1_register(CP1_STATUS);