x86: Fix x87 state transfer bug

Changeset 7274310be1bb (isa: clean up register constants) increased
the value of NumFloatRegs, which triggered a bug in
X86ISA::copyRegs(). This bug is caused by the x87 stack being copied
twice since register indexes past NUM_FLOATREGS are mapped into the
x87 stack relative to the top of the stack, which is undefined when
the copy takes place.

This changeset updates the copyRegs() function to use access registers
using the non-flattening interface, which guarantees that undesirable
register folding does not happen.

diff --git a/src/arch/x86/utility.cc b/src/arch/x86/utility.cc
index 8f1a419f12c681db7fdc4db2a027235aadb4de7f..fcd52d38ac0cbd6f9d94dc87d908c0c5e328acde 100644 (file)
--- a/src/arch/x86/utility.cc
+++ b/src/arch/x86/utility.cc
@@ -240,13 +240,13 @@ copyRegs(ThreadContext *src, ThreadContext *dest)
 {
     //copy int regs
     for (int i = 0; i < NumIntRegs; ++i)
-         dest->setIntReg(i, src->readIntReg(i));
+         dest->setIntRegFlat(i, src->readIntRegFlat(i));
     //copy float regs
     for (int i = 0; i < NumFloatRegs; ++i)
-         dest->setFloatRegBits(i, src->readFloatRegBits(i));
+         dest->setFloatRegBitsFlat(i, src->readFloatRegBitsFlat(i));
     //copy condition-code regs
     for (int i = 0; i < NumCCRegs; ++i)
-         dest->setCCReg(i, src->readCCReg(i));
+         dest->setCCRegFlat(i, src->readCCRegFlat(i));
     copyMiscRegs(src, dest);
     dest->pcState(src->pcState());
 }