Merge pull request #189 from atlas0fd00m/arch_modva_hooks

EASY: arch mod-va hooks

envi/__init__.py

@@ -156,6 +156,26 @@ def archGetRegisterGroups(self):
         allr = [rname for rname in regctx.getRegisterNames()]
         return [ ('all', allr), ]
 
+    def archModifyFuncAddr(self, va, info):
+        '''
+        Can modify the VA and context based on architecture-specific info.
+        Default: return the same va, info
+
+        This hook allows an architecture to correct VA and Architecture, such 
+        as is necessary for ARM/Thumb.
+        '''
+        return va, {}
+
+    def archModifyXrefAddr(self, tova, reftype, rflags):
+        '''
+        Returns a potentially modified set of (tova, reftype, rflags).
+        Default: return the same tova, reftype, rflags
+
+        This hook allows an architecture to modify an Xref before it's set, 
+        which can be helpful for ARM/Thumb.
+        '''
+        return tova, reftype, rflags
+
     def archGetBadOps(self, byteslist=None):
         '''
         Returns a list of opcodes which are indicators of wrong disassembly.

envi/archs/arm/__init__.py

@@ -52,6 +52,17 @@ def setEndian(self, endian):
         self._arch_dis.setEndian(endian)
         self._arch_thumb_dis.setEndian(endian)
 
+    def archModifyFuncAddr(self, va, info):
+        if va & 1:
+            return va & -2, {'arch' : envi.ARCH_THUMB2}
+        return va, {}
+
+    def archModifyXrefAddr(self, tova, reftype, rflags):
+        if tova & 1:
+            return tova & -2, reftype, rflags
+        return tova, reftype, rflags
+
+
 
 
 from envi.archs.arm.emu import *

envi/codeflow.py

@@ -261,6 +261,11 @@ def addEntryPoint(self, va, arch=envi.ARCH_DEFAULT):
             cf.addEntryPoint( 0x77c70308 )
             ... callbacks flow along ...
         '''
+        # Architecture gets to decide on actual final VA and Architecture (ARM/THUMB/etc...)
+        info = { 'arch' : arch }
+        va, info = self._mem.arch.archModifyFuncAddr(va, info)
+        arch = info.get('arch', envi.ARCH_DEFAULT)
+
         # Check if this is already a known function.
         if self._funcs.get(va) != None:
             return

vivisect/__init__.py

@@ -1475,7 +1475,10 @@ def addXref(self, fromva, tova, reftype, rflags=0):
         (see REF_ macros).  This will *not* trigger any analysis.
         Callers are expected to do their own xref analysis (ie, makeCode() etc)
         """
-        ref = (fromva,tova,reftype,rflags)
+        # Architecture gets to decide on actual final VA (ARM/THUMB/etc...)
+        tova, reftype, rflags = self.arch.archModifyXrefAddr(tova, reftype, rflags)
+
+        ref = (fromva, tova, reftype, rflags)
         if ref in self.getXrefsFrom(fromva):
             return
         self._fireEvent(VWE_ADDXREF, (fromva, tova, reftype, rflags))