powerpc/math-emu: Move the flush FPU state function into do_mathemu

By doing this we can make sure that the FPU state is only flushed to
the thread struct when it is really needed.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/traps.c

@@ -1134,15 +1134,6 @@ void __kprobes program_check_exception(struct pt_regs *regs)
 	 * instruction or only on FP instructions, whether there is a
 	 * pattern to occurrences etc. -dgibson 31/Mar/2003
 	 */
-
-	/*
-	 * If we support a HW FPU, we need to ensure the FP state
-	 * if flushed into the thread_struct before attempting
-	 * emulation
-	 */
-#ifdef CONFIG_PPC_FPU
-	flush_fp_to_thread(current);
-#endif
 	switch (do_mathemu(regs)) {
 	case 0:
 		emulate_single_step(regs);

arch/powerpc/math-emu/math.c

@@ -420,6 +420,15 @@ do_mathemu(struct pt_regs *regs)
 		goto illegal;
 	}
 
+	/*
+	 * If we support a HW FPU, we need to ensure the FP state
+	 * is flushed into the thread_struct before attempting
+	 * emulation
+	 */
+#ifdef CONFIG_PPC_FPU
+	flush_fp_to_thread(current);
+#endif
+
 	eflag = func(op0, op1, op2, op3);
 
 	if (insn & 1) {