arch-arm: AArch64 Instruction for MISCREG_IMPDEF_UNIMPL

While there is a AArch32 class for instructions accessing implementation
defined registers, we are lacking for the AArch64 counterpart.
we were relying on FailUnimplemented, which is untrappable at EL2 (except
for HCR_EL2.TGE) since it is just raising Undefined Instruction.

Change-Id: I923cb914658ca958af031612cf005159707b0b4f
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13779
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/src/arch/arm/insts/misc64.cc b/src/arch/arm/insts/misc64.cc
index b2761e76c..7df2f76ed 100644
--- a/src/arch/arm/insts/misc64.cc
+++ b/src/arch/arm/insts/misc64.cc
@@ -266,6 +266,8 @@ MiscRegOp64::checkEL2Trap(ThreadContext *tc, const MiscRegIndex misc_reg,
             assert(miscRead);
             trap_to_hyp = hcr.tid1 && el == EL1;
             break;
+          case MISCREG_IMPDEF_UNIMPL:
+            trap_to_hyp = hcr.tidcp && el == EL1;
           default:
             break;
         }
@@ -330,3 +332,33 @@ RegMiscRegImmOp64::generateDisassembly(
     printMiscReg(ss, op1);
     return ss.str();
 }
+
+Fault
+MiscRegImplDefined64::execute(ExecContext *xc,
+                              Trace::InstRecord *traceData) const
+{
+    auto tc = xc->tcBase();
+    const CPSR cpsr = tc->readMiscReg(MISCREG_CPSR);
+    const ExceptionLevel el = (ExceptionLevel) (uint8_t) cpsr.el;
+
+    Fault fault = trap(tc, miscReg, el, imm);
+
+    if (fault != NoFault) {
+        return fault;
+
+    } else if (warning) {
+        warn_once("\tinstruction '%s' unimplemented\n", fullMnemonic.c_str());
+        return NoFault;
+
+    } else {
+        return std::make_shared<UndefinedInstruction>(machInst, false,
+                                                      mnemonic);
+    }
+}
+
+std::string
+MiscRegImplDefined64::generateDisassembly(Addr pc,
+                                          const SymbolTable *symtab) const
+{
+    return csprintf("%-10s (implementation defined)", fullMnemonic.c_str());
+}