diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2017-02-14 11:11:04 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-03-11 14:45:18 +0300 |
| commit | 5a920155e388ec22a22e0532fb695b9215c9b34d (patch) | |
| tree | e92bef00945f4180419a0ea81bc667bb3f542054 /arch/x86/kernel/process.c | |
| parent | b9894a2f5bd18b1691cb6872c9afe32b148d0132 (diff) | |
| download | linux-5a920155e388ec22a22e0532fb695b9215c9b34d.tar.xz | |
x86/process: Optimize TIF_NOTSC switch
Provide and use a toggle helper instead of doing it with a branch.
x86_64: arch/x86/kernel/process.o
text data bss dec hex
3008 8577 16 11601 2d51 Before
2976 8577 16 11569 2d31 After
i386: arch/x86/kernel/process.o
text data bss dec hex
2925 8673 8 11606 2d56 Before
2893 8673 8 11574 2d36 After
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: http://lkml.kernel.org/r/20170214081104.9244-4-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 22 |
1 files changed, 4 insertions, 18 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 83fa3cb4f8f0..366db7782fc6 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -124,11 +124,6 @@ void flush_thread(void) fpu__clear(&tsk->thread.fpu); } -static void hard_disable_TSC(void) -{ - cr4_set_bits(X86_CR4_TSD); -} - void disable_TSC(void) { preempt_disable(); @@ -137,15 +132,10 @@ void disable_TSC(void) * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ - hard_disable_TSC(); + cr4_set_bits(X86_CR4_TSD); preempt_enable(); } -static void hard_enable_TSC(void) -{ - cr4_clear_bits(X86_CR4_TSD); -} - static void enable_TSC(void) { preempt_disable(); @@ -154,7 +144,7 @@ static void enable_TSC(void) * Must flip the CPU state synchronously with * TIF_NOTSC in the current running context. */ - hard_enable_TSC(); + cr4_clear_bits(X86_CR4_TSD); preempt_enable(); } @@ -233,12 +223,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); } - if ((tifp ^ tifn) & _TIF_NOTSC) { - if (tifn & _TIF_NOTSC) - hard_disable_TSC(); - else - hard_enable_TSC(); - } + if ((tifp ^ tifn) & _TIF_NOTSC) + cr4_toggle_bits(X86_CR4_TSD); } /* |