arch-power: Fix process initialization

During process initialization, special purpose registers
should either be explicitly set or cleared. These contain
flag bits which might have unforseen side effects on the
execution of a program.

Change-Id: If7c5af9a93283a53717cc8cbba4bf373a7e40560
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40945
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Maintainer: Boris Shingarov <shingarov@labware.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/power/process.cc

@@ -338,6 +338,10 @@ PowerProcess::argsInit(int pageSize)
     //Set the stack pointer register
     tc->setIntReg(StackPointerReg, stack_min);
 
+    //Reset the special-purpose registers
+    for (int i = 0; i < NumIntSpecialRegs; i++)
+        tc->setIntReg(NumIntArchRegs + i, 0);
+
     //Set the machine status for a typical userspace
     Msr msr = 0;
     msr.sf = is64bit;