Some improvements

- Added dint and halting to lifter
- Avoid setting the stack to a constant value for lifting
- Make 'sr' a global_regs to fix calling conventions
-

Author: Josh Watson

instructions.py

@@ -352,6 +352,13 @@ def decode(cls, data, address):
             mnemonic = 'br'
             emulated = True
 
+        elif (
+            mnemonic == 'bis' and
+            dst.target == 'sr' and
+            src.value == 0xf0
+        ):
+            return cls('dint', length=length, emulated=True)
+
         return cls(
             mnemonic,
             type_,

lifter.py

@@ -1,7 +1,7 @@
 from binaryninja import (LLIL_TEMP, Architecture, LowLevelILFlagCondition,
                          LowLevelILLabel, LowLevelILOperation)
 
-from .instructions import IMMEDIATE_MODE, INDIRECT_AUTOINCREMENT_MODE
+from .instructions import IMMEDIATE_MODE, INDIRECT_AUTOINCREMENT_MODE, REGISTER_MODE
 
 SourceOperandsIL = [
     # REGISTER_MODE
@@ -332,6 +332,14 @@ def lift_cmp(il, instr):
     def lift_dadd(il, instr):
         il.append(il.unimplemented())
 
+    @staticmethod
+    def lift_dint(il, instr):
+        pass
+
+    @staticmethod
+    def lift_hlt(il, instr):
+        il.append(il.no_ret())
+
     @staticmethod
     def lift_jge(il, instr):
         cond_branch(
@@ -408,6 +416,12 @@ def lift_jz(il, instr):
 
     @staticmethod
     def lift_mov(il, instr):
+        # avoid setting stack pointer to a constant
+        if (instr.src.mode == IMMEDIATE_MODE and
+                instr.dst.target == 'sp' and
+                instr.dst.mode == REGISTER_MODE):
+            return
+
         src = SourceOperandsIL[instr.src.mode](
             il, instr.src.width, instr.src.target, instr.src.value
         )

msp430.py

@@ -1,5 +1,3 @@
-import struct
-
 from binaryninja import (Architecture, FlagRole, LowLevelILFlagCondition,
                          RegisterInfo, log_error, InstructionInfo, BranchType, InstructionTextToken, InstructionTextTokenType)
 
@@ -10,6 +8,8 @@ class MSP430(Architecture):
     name = 'msp430'
     address_size = 2
     default_int_size = 2
+    global_regs = ['sr']
+    stack_pointer = 'sp'
 
     regs = {r: RegisterInfo(r, 2) for r in Registers}
 
@@ -42,8 +42,6 @@ class MSP430(Architecture):
         LowLevelILFlagCondition.LLFC_POS: ['n']
     }
 
-    stack_pointer = 'sp'
-
     def perform_get_instruction_info(self, data, addr):
         instr = Instruction.decode(data, addr)
 
@@ -81,6 +79,15 @@ def perform_get_instruction_low_level_il(self, data, addr, il):
 
         if instr is None:
             return None
+
+        # Halting the system means turning off interrupts and just looping
+        # indefinitely
+        if instr.mnemonic == 'dint':
+            next_instr = Instruction.decode(
+                data[instr.length:], addr + instr.length
+            )
+            if next_instr.mnemonic == 'jmp' and next_instr.src.value == addr:
+                instr.mnemonic = 'hlt'
 
         Lifter.lift(il, instr)