xen: support sysenter/sysexit if hypervisor does
64-bit Xen supports sysenter for 32-bit guests, so support its
use. (sysenter is faster than int $0x80 in 32-on-64.)
sysexit is still not supported, so we fake it up using iret.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 956a491..01d4ff2 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -19,6 +19,7 @@
char * __init xen_memory_setup(void);
void __init xen_arch_setup(void);
void __init xen_init_IRQ(void);
+void xen_enable_sysenter(void);
void xen_setup_timer(int cpu);
void xen_setup_cpu_clockevents(void);
@@ -64,4 +65,6 @@
DECL_ASM(void, xen_restore_fl_direct, unsigned long);
void xen_iret(void);
+void xen_sysexit(void);
+
#endif /* XEN_OPS_H */