fix several missing or invalid decodings among 0f01 opcodes

* `mwaitx`, `monitorx`, `rdpru`, and `clzero` are now supported
* swapgs is no longer decoded in protected mode
* rdpkru and wrpkru are no longer decoded if mod bits != 11

2 files changed, 47 insertions, 3 deletions

diff --git a/src/protected_mode/display.rs b/src/protected_mode/display.rs
index c92737b..a0161c2 100644
--- a/src/protected_mode/display.rs
+++ b/src/protected_mode/display.rs
@@ -504,6 +504,8 @@ const MNEMONICS: &[&'static str] = &[
     "vmxoff",
     "monitor",
     "mwait",
+    "monitorx",
+    "mwaitx",
     "clac",
     "stac",
     "encls",
@@ -518,6 +520,8 @@ const MNEMONICS: &[&'static str] = &[
     "enclu",
     "rdpkru",
     "wrpkru",
+    "rdpru",
+    "clzero",
     "rdseed",
     "rdrand",
     "addps",
@@ -2162,6 +2166,8 @@ impl <T: fmt::Write, Color: fmt::Display, Y: YaxColors<Color>> Colorize<T, Color
             Opcode::VMXOFF |
             Opcode::MONITOR |
             Opcode::MWAIT |
+            Opcode::MONITORX |
+            Opcode::MWAITX |
             Opcode::SKINIT |
             Opcode::CLGI |
             Opcode::STGI |
@@ -2179,6 +2185,8 @@ impl <T: fmt::Write, Color: fmt::Display, Y: YaxColors<Color>> Colorize<T, Color
             Opcode::ENCLU |
             Opcode::RDPKRU |
             Opcode::WRPKRU |
+            Opcode::RDPRU |
+            Opcode::CLZERO |
             Opcode::ARPL |
             Opcode::LAR => { write!(out, "{}", colors.platform_op(self)) }
 
diff --git a/src/protected_mode/mod.rs b/src/protected_mode/mod.rs
index b60ff34..9327f64 100644
--- a/src/protected_mode/mod.rs
+++ b/src/protected_mode/mod.rs
@@ -1036,6 +1036,8 @@ pub enum Opcode {
     VMXOFF,
     MONITOR,
     MWAIT,
+    MONITORX,
+    MWAITX,
     CLAC,
     STAC,
     ENCLS,
@@ -1051,6 +1053,9 @@ pub enum Opcode {
     RDPKRU,
     WRPKRU,
 
+    RDPRU,
+    CLZERO,
+
     RDSEED,
     RDRAND,
 
@@ -3191,6 +3196,12 @@ impl InstDecoder {
                     return Err(DecodeError::InvalidOpcode);
                 }
             }
+            Opcode::MONITORX | Opcode::MWAITX | // these are gated on the `monitorx` and `mwaitx` cpuid bits, but are AMD-only.
+            Opcode::CLZERO | Opcode::RDPRU => { // again, gated on specific cpuid bits, but AMD-only.
+                if !self.amd_quirks() {
+                    return Err(DecodeError::InvalidOpcode);
+                }
+            }
             other => {
                 if !self.bmi1() {
                     if BMI1.contains(&other) {
@@ -7893,6 +7904,14 @@ fn unlikely_operands<T: Iterator<Item=u8>>(decoder: &InstDecoder, mut bytes_iter
                 instruction.operand_count = 1;
                 instruction.operands[0] = read_E(&mut bytes_iter, instruction, modrm, 2, length)?;
             } else if r == 5 {
+                let mod_bits = modrm >> 6;
+                if mod_bits != 0b11 {
+                    instruction.opcode = Opcode::Invalid;
+                    instruction.operands[0] = OperandSpec::Nothing;
+                    instruction.operand_count = 0;
+                    return Err(DecodeError::InvalidOpcode);
+                }
+
                 let m = modrm & 7;
                 match m {
                     0b110 => {
@@ -7921,13 +7940,30 @@ fn unlikely_operands<T: Iterator<Item=u8>>(decoder: &InstDecoder, mut bytes_iter
                 let m = modrm & 7;
                 if mod_bits == 0b11 {
                     if m == 0 {
-                        instruction.opcode = Opcode::SWAPGS;
-                        instruction.operands[0] = OperandSpec::Nothing;
-                        instruction.operand_count = 0;
+                        // swapgs is not valid in modes other than 64-bit
+                        instruction.opcode = Opcode::Invalid;
+                        return Err(DecodeError::InvalidOpcode);
                     } else if m == 1 {
                         instruction.opcode = Opcode::RDTSCP;
                         instruction.operands[0] = OperandSpec::Nothing;
                         instruction.operand_count = 0;
+                    } else if m == 2 {
+                        instruction.opcode = Opcode::MONITORX;
+                        instruction.operands[0] = OperandSpec::Nothing;
+                        instruction.operand_count = 0;
+                    } else if m == 3 {
+                        instruction.opcode = Opcode::MWAITX;
+                        instruction.operands[0] = OperandSpec::Nothing;
+                        instruction.operand_count = 0;
+                    } else if m == 4 {
+                        instruction.opcode = Opcode::CLZERO;
+                        instruction.operands[0] = OperandSpec::Nothing;
+                        instruction.operand_count = 0;
+                    } else if m == 5 {
+                        instruction.opcode = Opcode::RDPRU;
+                        instruction.operands[0] = OperandSpec::RegRRR;
+                        instruction.modrm_rrr = RegSpec::ecx();
+                        instruction.operand_count = 1;
                     } else {
                         instruction.opcode = Opcode::Invalid;
                         return Err(DecodeError::InvalidOpcode);