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Commit 91066588 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarBorislav 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: default avatarIngo Molnar <mingo@kernel.org>
parent 952f07ec

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

+2 −25
Original line number Diff line number Diff line
@@ -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

+30 −0
Original line number Diff line number Diff line
@@ -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()) {