Index: head/sys/amd64/amd64/fpu.c
===================================================================
--- head/sys/amd64/amd64/fpu.c
+++ head/sys/amd64/amd64/fpu.c
@@ -61,6 +61,7 @@
 #include <machine/specialreg.h>
 #include <machine/segments.h>
 #include <machine/ucontext.h>
+#include <x86/ifunc.h>
 
 /*
  * Floating point support.
@@ -151,26 +152,60 @@
 	u_int	size;
 } *xsave_area_desc;
 
-void
-fpusave(void *addr)
+static void
+fpusave_xsave(void *addr)
 {
 
-	if (use_xsave)
-		xsave((char *)addr, xsave_mask);
-	else
-		fxsave((char *)addr);
+	xsave((char *)addr, xsave_mask);
 }
 
-void
-fpurestore(void *addr)
+static void
+fpurestore_xrstor(void *addr)
 {
 
+	xrstor((char *)addr, xsave_mask);
+}
+
+static void
+fpusave_fxsave(void *addr)
+{
+
+	fxsave((char *)addr);
+}
+
+static void
+fpurestore_fxrstor(void *addr)
+{
+
+	fxrstor((char *)addr);
+}
+
+static void
+init_xsave(void)
+{
+
 	if (use_xsave)
-		xrstor((char *)addr, xsave_mask);
-	else
-		fxrstor((char *)addr);
+		return;
+	if ((cpu_feature2 & CPUID2_XSAVE) == 0)
+		return;
+	use_xsave = 1;
+	TUNABLE_INT_FETCH("hw.use_xsave", &use_xsave);
 }
 
+DEFINE_IFUNC(, void, fpusave, (void *), static)
+{
+
+	init_xsave();
+	return (use_xsave ? fpusave_xsave : fpusave_fxsave);
+}
+
+DEFINE_IFUNC(, void, fpurestore, (void *), static)
+{
+
+	init_xsave();
+	return (use_xsave ? fpurestore_xrstor : fpurestore_fxrstor);
+}
+
 void
 fpususpend(void *addr)
 {
@@ -207,13 +242,8 @@
 	uint64_t xsave_mask_user;
 	bool old_wp;
 
-	if ((cpu_feature2 & CPUID2_XSAVE) != 0) {
-		use_xsave = 1;
-		TUNABLE_INT_FETCH("hw.use_xsave", &use_xsave);
-	}
 	if (!use_xsave)
 		return;
-
 	cpuid_count(0xd, 0x0, cp);
 	xsave_mask = XFEATURE_ENABLED_X87 | XFEATURE_ENABLED_SSE;
 	if ((cp[0] & xsave_mask) != xsave_mask)