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>
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@@ -110,6 +110,16 @@ static inline void cr4_clear_bits(unsigned long mask)
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}
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}
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static inline void cr4_toggle_bits(unsigned long mask)
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{
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unsigned long cr4;
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cr4 = this_cpu_read(cpu_tlbstate.cr4);
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cr4 ^= mask;
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this_cpu_write(cpu_tlbstate.cr4, cr4);
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__write_cr4(cr4);
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}
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/* Read the CR4 shadow. */
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static inline unsigned long cr4_read_shadow(void)
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{
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