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authorAndy Lutomirski <luto@amacapital.net>2014-10-31 00:58:01 +0300
committerThomas Gleixner <tglx@linutronix.de>2014-11-03 15:41:53 +0300
commite76b027e6408f5570dc940b731ec9ae870c6188a (patch)
treed94287f98ee13c7e2fedd4890499f178079ce6ab /arch/x86/include/asm/vgtod.h
parenta92f101bc99d17b75021cf29f18cc57f39a37d1f (diff)
downloadlinux-e76b027e6408f5570dc940b731ec9ae870c6188a.tar.xz
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.h19
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 */