X86: Start implementing segmentation support.

Make instructions observe segment prefixes, default segment rules, segment
base addresses.
Also fix some microcode and add sib and riprel "keywords" to the x86
specialization of the microassembler.

--HG--
extra : convert_revision : be5a3b33d33f243ed6e1ad63faea8495e46d0ac9

1 files changed, 13 insertions, 0 deletions

diff --git a/src/arch/x86/emulenv.cc b/src/arch/x86/emulenv.cc
index 28282dc7a..31b705d79 100644
--- a/src/arch/x86/emulenv.cc
+++ b/src/arch/x86/emulenv.cc
@@ -88,5 +88,18 @@ void EmulEnv::doModRM(const ExtMachInst & machInst)
             }
         }
     }
+    //Figure out what segment to use. This won't be entirely accurate since
+    //the presence of a displacement is supposed to make the instruction
+    //default to the data segment.
+    if (base != INTREG_RBP && base != INTREG_RSP ||
+            0/*Has an immediate offset*/) {
+        seg = SEGMENT_REG_DS;
+        //Handle any segment override that might have been in the instruction
+        int segFromInst = machInst.legacy.seg;
+        if (segFromInst)
+            seg = (SegmentRegIndex)(segFromInst - 1);
+    } else {
+        seg = SEGMENT_REG_SS;
+    }
 }