diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-10-30 14:58:01 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2014-11-03 13:41:53 +0100 |
| commit | e76b027e6408f5570dc940b731ec9ae870c6188a (patch) | |
| tree | d94287f98ee13c7e2fedd4890499f178079ce6ab /arch/x86/include/asm/vgtod.h | |
| parent | a92f101bc99d17b75021cf29f18cc57f39a37d1f (diff) | |
x86,vdso: Use LSL unconditionally for vgetcpu
LSL is faster than RDTSCP and works everywhere; there's no need to
switch between them depending on CPU.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Andi Kleen <andi@firstfloor.org>
Link: http://lkml.kernel.org/r/72f73d5ec4514e02bba345b9759177ef03742efb.1414706021.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/include/asm/vgtod.h')
| -rw-r--r-- | arch/x86/include/asm/vgtod.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index 3c3366c2e37f..e7e9682a33e9 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -70,4 +70,23 @@ static inline void gtod_write_end(struct vsyscall_gtod_data *s) ++s->seq; } +#ifdef CONFIG_X86_64 + +#define VGETCPU_CPU_MASK 0xfff + +static inline unsigned int __getcpu(void) +{ + unsigned int p; + + /* + * Load per CPU data from GDT. LSL is faster than RDTSCP and + * works on all CPUs. + */ + asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG)); + + return p; +} + +#endif /* CONFIG_X86_64 */ + #endif /* _ASM_X86_VGTOD_H */ |