--- sys/amd64/amd64/support.S.orig
+++ sys/amd64/amd64/support.S
@@ -919,9 +919,11 @@
 END(copyin_smap_erms)
 
 	ALIGN_TEXT
-	/* Trap entry clears PSL.AC */
 copy_fault:
-	movq	$0,PCB_ONFAULT(%r11)
+	testl	$CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip)
+	je	1f
+	clac
+1:	movq	$0,PCB_ONFAULT(%r11)
 	movl	$EFAULT,%eax
 	POP_FRAME_POINTER
 	ret
@@ -1358,9 +1360,11 @@
 END(subyte_smap)
 
 	ALIGN_TEXT
-	/* Fault entry clears PSL.AC */
 fusufault:
-	movq	PCPU(CURPCB),%rcx
+	testl	$CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip)
+	je	1f
+	clac
+1:	movq	PCPU(CURPCB),%rcx
 	xorl	%eax,%eax
 	movq	%rax,PCB_ONFAULT(%rcx)
 	decq	%rax
@@ -1443,8 +1447,10 @@
 END(copyinstr_smap)
 
 cpystrflt:
-	/* Fault entry clears PSL.AC */
-	movl	$EFAULT,%eax
+	testl	$CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip)
+	je	1f
+	clac
+1:	movl	$EFAULT,%eax
 cpystrflt_x:
 	/* set *lencopied and return %eax */
 	movq	$0,PCB_ONFAULT(%r9)
--- sys/amd64/linux/linux_support.s.orig
+++ sys/amd64/linux/linux_support.s
@@ -30,11 +30,15 @@
 
 #include "linux_assym.h"		/* system definitions */
 #include <machine/asmacros.h>		/* miscellaneous asm macros */
+#include <machine/specialreg.h>
 
 #include "assym.inc"
 
 futex_fault:
-	movq	$0,PCB_ONFAULT(%r8)
+	testl	$CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip)
+	je	1f
+	clac
+1:	movq	$0,PCB_ONFAULT(%r8)
 	movl	$-EFAULT,%eax
 	ret
 
--- sys/amd64/linux32/linux32_support.s.orig
+++ sys/amd64/linux32/linux32_support.s
@@ -30,11 +30,15 @@
 
 #include "linux32_assym.h"		/* system definitions */
 #include <machine/asmacros.h>		/* miscellaneous asm macros */
+#include <machine/specialreg.h>
 
 #include "assym.inc"
 
 futex_fault:
-	movq	$0,PCB_ONFAULT(%r8)
+	testl	$CPUID_STDEXT_SMAP,cpu_stdext_feature(%rip)
+	je	1f
+	clac
+1:	movq	$0,PCB_ONFAULT(%r8)
 	movl	$-EFAULT,%eax
 	ret