diff --git a/src/arch/x86/isa/decoder/two_byte_opcodes.isa b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
index e55756fec..c344ee550 100644
--- a/src/arch/x86/isa/decoder/two_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
@@ -125,7 +125,7 @@
                             0x6: skinit();
                             0x7: invlpga();
                         }
-                        0x4: smsw_Rv();
+                        0x4: Inst::SMSW(Rv);
                         0x6: Inst::LMSW(Rv);
                         0x7: decode MODRM_RM {
                             0x0: Inst::SWAPGS();
@@ -155,7 +155,7 @@
                                 default: Inst::LIDT(M);
                             }
                         }
-                        0x4: smsw_Mw();
+                        0x4: Inst::SMSW(Mw);
                         0x6: Inst::LMSW(Mw);
                         0x7: Inst::INVLPG(M);
                         default: Inst::UD2();
diff --git a/src/arch/x86/isa/insts/system/control_registers.py b/src/arch/x86/isa/insts/system/control_registers.py
index c09cdf6e8..82811bb07 100644
--- a/src/arch/x86/isa/insts/system/control_registers.py
+++ b/src/arch/x86/isa/insts/system/control_registers.py
@@ -68,4 +68,19 @@ def macroop LMSW_P {
     or t1, t1, t2, dataSize=8
     wrcr 0, t1, dataSize=8
 };
+
+def macroop SMSW_R {
+    rdcr reg, 0
+};
+
+def macroop SMSW_M {
+    rdcr t1, 0
+    st t1, seg, sib, disp, dataSize=2
+};
+
+def macroop SMSW_P {
+    rdcr t1, 0
+    rdip t7, dataSize=asz
+    st t1, seg, riprel, disp, dataSize=2
+};
 '''