openrisc: Add FPU config

Allow disabling FPU related code sequences to save space.
Signed-off-by: Stafford Horne <shorne@gmail.com>

arch/openrisc/Kconfig

@@ -188,6 +188,15 @@ config SMP
 
 	  If you don't know what to do here, say N.
 
+config FPU
+	bool "FPU support"
+	default y
+	help
+	  Say N here if you want to disable all floating-point related procedures
+	  in the kernel and reduce binary size.
+
+	  If you don't know what to do here, say Y.
+
 source "kernel/Kconfig.hz"
 
 config OPENRISC_NO_SPR_SR_DSX

arch/openrisc/kernel/ptrace.c

@@ -88,6 +88,7 @@ static int genregs_set(struct task_struct *target,
 	return ret;
 }
 
+#ifdef CONFIG_FPU
 /*
  * As OpenRISC shares GPRs and floating point registers we don't need to export
  * the floating point registers again.  So here we only export the fpcsr special
@@ -115,13 +116,16 @@ static int fpregs_set(struct task_struct *target,
 				 &regs->fpcsr, 0, 4);
 	return ret;
 }
+#endif
 
 /*
  * Define the register sets available on OpenRISC under Linux
  */
 enum or1k_regset {
 	REGSET_GENERAL,
+#ifdef CONFIG_FPU
 	REGSET_FPU,
+#endif
 };
 
 static const struct user_regset or1k_regsets[] = {
@@ -133,6 +137,7 @@ static const struct user_regset or1k_regsets[] = {
 			    .regset_get = genregs_get,
 			    .set = genregs_set,
 			    },
+#ifdef CONFIG_FPU
 	[REGSET_FPU] = {
 			    .core_note_type = NT_PRFPREG,
 			    .n = sizeof(struct __or1k_fpu_state) / sizeof(long),
@@ -141,6 +146,7 @@ static const struct user_regset or1k_regsets[] = {
 			    .regset_get = fpregs_get,
 			    .set = fpregs_set,
 			    },
+#endif
 };
 
 static const struct user_regset_view user_or1k_native_view = {

arch/openrisc/kernel/traps.c

@@ -182,6 +182,7 @@ asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
 {
 	if (user_mode(regs)) {
 		int code = FPE_FLTUNK;
+#ifdef CONFIG_FPU
 		unsigned long fpcsr = regs->fpcsr;
 
 		if (fpcsr & SPR_FPCSR_IVF)
@@ -197,7 +198,7 @@ asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
 
 		/* Clear all flags */
 		regs->fpcsr &= ~SPR_FPCSR_ALLF;
-
+#endif
 		force_sig_fault(SIGFPE, code, (void __user *)regs->pc);
 	} else {
 		pr_emerg("KERNEL: Illegal fpe exception 0x%.8lx\n", regs->pc);