fix misdecode of instructions in opcode 0x800.1.3

6 files changed, 9 insertions, 1 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 6e811e0..5f0b9f7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+## 0.1.3
+* fix 0x80-opcode instructions not having an opcode
+  - this meant that for example `lock xorb [rax], 0` would decode as invalid
+
 ## 0.1.2
 * expose constructors for `RegSpec` in both `long_mode` and `protected_mode`
 * expose a const `RegSpec::RIP`
diff --git a/Cargo.toml b/Cargo.toml
index 10f0962..c6da196 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "yaxpeax-x86"
-version = "0.1.2"
+version = "0.1.3"
 authors = [ "iximeow <me@iximeow.net>" ]
 license = "0BSD"
 repository = "http://git.iximeow.net/yaxpeax-x86/"
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index 94e34ae..363c605 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -6171,6 +6171,7 @@ fn read_operands<T: Iterator<Item=u8>>(decoder: &InstDecoder, mut bytes_iter: T,
             instruction.operand_count = 1;
         },
         1 => {
+            instruction.opcode = base_opcode_map((modrm >> 3) & 7);
             instruction.operands[0] = mem_oper;
             instruction.operands[1] = OperandSpec::ImmI8;
             instruction.operand_count = 2;
diff --git a/src/protected_mode/mod.rs b/src/protected_mode/mod.rs
index 29c2750..b60ff34 100644
--- a/src/protected_mode/mod.rs
+++ b/src/protected_mode/mod.rs
@@ -6023,6 +6023,7 @@ fn read_operands<T: Iterator<Item=u8>>(decoder: &InstDecoder, mut bytes_iter: T,
             instruction.operand_count = 1;
         },
         1 => {
+            instruction.opcode = base_opcode_map((modrm >> 3) & 7);
             instruction.operands[0] = mem_oper;
             instruction.operands[1] = OperandSpec::ImmI8;
             instruction.operand_count = 2;
diff --git a/test/long_mode/mod.rs b/test/long_mode/mod.rs
index 33fc8c7..3b31dbb 100644
--- a/test/long_mode/mod.rs
+++ b/test/long_mode/mod.rs
@@ -1097,6 +1097,7 @@ fn test_prefixes() {
     test_display(&[0x40, 0x32, 0xc5], "xor al, bpl");
     test_invalid(&[0xf0, 0x33, 0xc0]);
     test_display(&[0xf0, 0x31, 0x00], "lock xor [rax], eax");
+    test_display(&[0xf0, 0x80, 0x30, 0x00], "lock xor [rax], 0x0");
     test_invalid(&[0xf0, 0xc7, 0x00, 0x00, 0x00, 0x00]);
 }
 
diff --git a/test/protected_mode/mod.rs b/test/protected_mode/mod.rs
index c5c3c7b..84448ef 100644
--- a/test/protected_mode/mod.rs
+++ b/test/protected_mode/mod.rs
@@ -972,6 +972,7 @@ fn test_prefixes() {
     test_display(&[0x66, 0x32, 0xc5], "xor al, ch");
     test_invalid(&[0xf0, 0x33, 0xc0]);
     test_display(&[0xf0, 0x31, 0x00], "lock xor [eax], eax");
+    test_display(&[0xf0, 0x80, 0x30, 0x00], "lock xor [eax], 0x0");
     test_invalid(&[0xf0, 0xc7, 0x00, 0x00, 0x00, 0x00]);
 }