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

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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>
This commit is contained in:
Ingo Molnar 2015-04-26 16:57:55 +02:00
parent 952f07ecbd
commit 910665882f
2 changed files with 32 additions and 25 deletions
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27
arch/x86/include/asm/fpu/api.h
View File

@ -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 */

30
arch/x86/kernel/fpu/core.c
View File

@ -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()) {