4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <t...@linutronix.de> commit 5a920155e388ec22a22e0532fb695b9215c9b34d upstream 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 <t...@linutronix.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Andy Lutomirski <l...@kernel.org> Link: http://lkml.kernel.org/r/20170214081104.9244-4-kh...@kylehuey.com Signed-off-by: Thomas Gleixner <t...@linutronix.de> Signed-off-by: David Woodhouse <d...@amazon.co.uk> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- arch/x86/include/asm/tlbflush.h | 10 ++++++++++ arch/x86/kernel/process.c | 22 ++++------------------ 2 files changed, 14 insertions(+), 18 deletions(-) --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -111,6 +111,16 @@ static inline void cr4_clear_bits(unsign } } +static inline void cr4_toggle_bits(unsigned long mask) +{ + unsigned long cr4; + + cr4 = this_cpu_read(cpu_tlbstate.cr4); + cr4 ^= mask; + this_cpu_write(cpu_tlbstate.cr4, cr4); + __write_cr4(cr4); +} + /* Read the CR4 shadow. */ static inline unsigned long cr4_read_shadow(void) { --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -134,11 +134,6 @@ 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(); @@ -147,15 +142,10 @@ 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(); @@ -164,7 +154,7 @@ 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(); } @@ -238,12 +228,8 @@ void __switch_to_xtra(struct task_struct 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); } /*
