x86/fpu: Uninline the irq_ts_save()/restore() functions

Especially the irq_ts_save() function is pretty bloaty, generating
over a dozen instructions, so uninline them.

Even though the API is used rarely, the space savings are measurable:

   text    data     bss     dec     hex filename
   13331995        2572920 1634304 17539219        10ba093 vmlinux.before
   13331739        2572920 1634304 17538963        10b9f93 vmlinux.after

( This also allows the removal of an include file inclusion from fpu/api.h,
  speeding up the kernel build slightly. )

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/fpu/api.h

@@ -10,8 +10,6 @@
 #ifndef _ASM_X86_FPU_API_H
 #define _ASM_X86_FPU_API_H
 
-#include <linux/hardirq.h>
-
 /*
  * Careful: __kernel_fpu_begin/end() must be called with preempt disabled
  * and they don't touch the preempt state on their own.
@@ -35,28 +33,7 @@ extern bool irq_fpu_usable(void);
  * in interrupt context interacting wrongly with other user/kernel fpu usage, we
  * should use them only in the context of irq_ts_save/restore()
  */
-static inline int irq_ts_save(void)
-{
-	/*
-	 * If in process context and not atomic, we can take a spurious DNA fault.
-	 * Otherwise, doing clts() in process context requires disabling preemption
-	 * or some heavy lifting like kernel_fpu_begin()
-	 */
-	if (!in_atomic())
-		return 0;
-
-	if (read_cr0() & X86_CR0_TS) {
-		clts();
-		return 1;
-	}
-
-	return 0;
-}
-
-static inline void irq_ts_restore(int TS_state)
-{
-	if (TS_state)
-		stts();
-}
+extern int  irq_ts_save(void);
+extern void irq_ts_restore(int TS_state);
 
 #endif /* _ASM_X86_FPU_API_H */

arch/x86/kernel/fpu/core.c

@@ -6,6 +6,7 @@
  *	Gareth Hughes <gareth@valinux.com>, May 2000
  */
 #include <asm/fpu/internal.h>
+#include <linux/hardirq.h>
 
 /*
  * Track whether the kernel is using the FPU state
@@ -140,6 +141,35 @@ void kernel_fpu_end(void)
 }
 EXPORT_SYMBOL_GPL(kernel_fpu_end);
 
+/*
+ * CR0::TS save/restore functions:
+ */
+int irq_ts_save(void)
+{
+	/*
+	 * If in process context and not atomic, we can take a spurious DNA fault.
+	 * Otherwise, doing clts() in process context requires disabling preemption
+	 * or some heavy lifting like kernel_fpu_begin()
+	 */
+	if (!in_atomic())
+		return 0;
+
+	if (read_cr0() & X86_CR0_TS) {
+		clts();
+		return 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_ts_save);
+
+void irq_ts_restore(int TS_state)
+{
+	if (TS_state)
+		stts();
+}
+EXPORT_SYMBOL_GPL(irq_ts_restore);
+
 static void __save_fpu(struct fpu *fpu)
 {
 	if (use_xsave()) {