x86: Centaur Isaiah processor to use sysenter in 64-bit compatibility mode rather than syscall

Upcoming 64 bit processors from Centaur can use sysenter.

Signed-off-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Jesse Ahrens <jahrens@centtech.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index f7e78d8..e2af8ee 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -210,8 +210,12 @@
 /* May not be __init: called during resume */
 void syscall32_cpu_init(void)
 {
-	if (use_sysenter < 0)
-		use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL);
+	if (use_sysenter < 0) {
+		if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+			use_sysenter = 1;
+		if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR)
+			use_sysenter = 1;
+	}
 
 	/* Load these always in case some future AMD CPU supports
 	   SYSENTER from compat mode too. */