From f057c712f91b215034fe84fa0f22694aaa8dffb3 Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Fri, 15 Jan 2021 14:52:11 -0800
Subject: 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
---
 src/protected_mode/mod.rs | 42 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

(limited to 'src/protected_mode/mod.rs')

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);
-- 
cgit v1.1