arch-arm: Removing FlushPipe fault, using SquashAfter

This Patch is removing the FlushPipe ArmFault, which was used for
flushing the pipeline in favour of the general IsSquashAfter StaticInstr
flag. Using a fault was preventing tracers from tracing barriers like
ISB and from adding them to the instruction count

Change-Id: I176e9254eca904694f2f611eb486c55e50ec61ff
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5361
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/arch/arm/faults.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2012-2014, 2016 ARM Limited
+ * Copyright (c) 2010, 2012-2014, 2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -278,11 +278,6 @@ template<> ArmFault::FaultVals ArmFaultVals<SystemError>::vals = {
     "SError",                0x000, 0x180, 0x380, 0x580, 0x780, MODE_SVC,
     0, 0, 0, 0, false, true,  true,  EC_SERROR, FaultStat()
 };
-template<> ArmFault::FaultVals ArmFaultVals<FlushPipe>::vals = {
-    // Some dummy values
-    "Pipe Flush",            0x000, 0x000, 0x000, 0x000, 0x000, MODE_SVC,
-    0, 0, 0, 0, false, true,  true,  EC_UNKNOWN, FaultStat()
-};
 template<> ArmFault::FaultVals ArmFaultVals<ArmSev>::vals = {
     // Some dummy values
     "ArmSev Flush",          0x000, 0x000, 0x000, 0x000, 0x000, MODE_SVC,
@@ -1398,19 +1393,6 @@ SystemError::routeToHyp(ThreadContext *tc) const
     return toHyp;
 }
 
-void
-FlushPipe::invoke(ThreadContext *tc, const StaticInstPtr &inst) {
-    DPRINTF(Faults, "Invoking FlushPipe Fault\n");
-
-    // Set the PC to the next instruction of the faulting instruction.
-    // Net effect is simply squashing all instructions behind and
-    // start refetching from the next instruction.
-    PCState pc = tc->pcState();
-    assert(inst);
-    inst->advancePC(pc);
-    tc->pcState(pc);
-}
-
 void
 ArmSev::invoke(ThreadContext *tc, const StaticInstPtr &inst) {
     DPRINTF(Faults, "Invoking ArmSev Fault\n");
@@ -1443,7 +1425,6 @@ template class ArmFaultVals<SecureMonitorTrap>;
 template class ArmFaultVals<PCAlignmentFault>;
 template class ArmFaultVals<SPAlignmentFault>;
 template class ArmFaultVals<SystemError>;
-template class ArmFaultVals<FlushPipe>;
 template class ArmFaultVals<ArmSev>;
 template class AbortFault<PrefetchAbort>;
 template class AbortFault<DataAbort>;

src/arch/arm/faults.hh

@@ -545,15 +545,6 @@ class SystemError : public ArmFaultVals<SystemError>
     bool routeToHyp(ThreadContext *tc) const override;
 };
 
-// A fault that flushes the pipe, excluding the faulting instructions
-class FlushPipe : public ArmFaultVals<FlushPipe>
-{
-  public:
-    FlushPipe() {}
-    void invoke(ThreadContext *tc, const StaticInstPtr &inst =
-                StaticInst::nullStaticInstPtr) override;
-};
-
 // A fault that flushes the pipe, excluding the faulting instructions
 class ArmSev : public ArmFaultVals<ArmSev>
 {
@@ -592,7 +583,6 @@ template<> ArmFault::FaultVals ArmFaultVals<SecureMonitorTrap>::vals;
 template<> ArmFault::FaultVals ArmFaultVals<PCAlignmentFault>::vals;
 template<> ArmFault::FaultVals ArmFaultVals<SPAlignmentFault>::vals;
 template<> ArmFault::FaultVals ArmFaultVals<SystemError>::vals;
-template<> ArmFault::FaultVals ArmFaultVals<FlushPipe>::vals;
 template<> ArmFault::FaultVals ArmFaultVals<ArmSev>::vals;
 
 

src/arch/arm/insts/pseudo.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014,2016 ARM Limited
+ * Copyright (c) 2014,2016-2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -190,6 +190,9 @@ McrMrcMiscInst::McrMrcMiscInst(const char *_mnemonic, ExtMachInst _machInst,
     flags[IsNonSpeculative] = true;
     iss = _iss;
     miscReg = _miscReg;
+
+    if (miscReg == MISCREG_DCCMVAC)
+        flags[IsSquashAfter] = true;
 }
 
 Fault
@@ -207,12 +210,9 @@ McrMrcMiscInst::execute(ExecContext *xc, Trace::InstRecord *traceData) const
     if (hypTrap) {
         return std::make_shared<HypervisorTrap>(machInst, iss,
                                                 EC_TRAPPED_CP15_MCR_MRC);
-    }
-
-    if (miscReg == MISCREG_DCCMVAC)
-        return std::make_shared<FlushPipe>();
-    else
+    } else {
         return NoFault;
+    }
 }
 
 std::string

src/arch/arm/isa/insts/misc.isa

@@ -1070,12 +1070,11 @@ let {{
             return std::make_shared<HypervisorTrap>(machInst, imm,
                 EC_TRAPPED_CP15_MCR_MRC);
         }
-        fault = std::make_shared<FlushPipe>();
     '''
     isbIop = InstObjParams("isb", "Isb", "ImmOp",
                              {"code": isbCode,
                                "predicate_test": predicateTest},
-                                ['IsSerializeAfter'])
+                                ['IsSerializeAfter', 'IsSquashAfter'])
     header_output += ImmOpDeclare.subst(isbIop)
     decoder_output += ImmOpConstructor.subst(isbIop)
     exec_output += PredOpExecute.subst(isbIop)
@@ -1087,12 +1086,12 @@ let {{
             return std::make_shared<HypervisorTrap>(machInst, imm,
                 EC_TRAPPED_CP15_MCR_MRC);
         }
-        fault = std::make_shared<FlushPipe>();
     '''
     dsbIop = InstObjParams("dsb", "Dsb", "ImmOp",
                              {"code": dsbCode,
                                "predicate_test": predicateTest},
-                              ['IsMemBarrier', 'IsSerializeAfter'])
+                              ['IsMemBarrier', 'IsSerializeAfter',
+                               'IsSquashAfter'])
     header_output += ImmOpDeclare.subst(dsbIop)
     decoder_output += ImmOpConstructor.subst(dsbIop)
     exec_output += PredOpExecute.subst(dsbIop)

src/arch/arm/isa/insts/misc64.isa

@@ -139,16 +139,15 @@ let {{
     decoder_output += BasicConstructor64.subst(unknown64Iop)
     exec_output += BasicExecute.subst(unknown64Iop)
 
-    isbIop = InstObjParams("isb", "Isb64", "ArmStaticInst",
-                           "fault = std::make_shared<FlushPipe>();",
-                           ['IsSerializeAfter'])
+    isbIop = InstObjParams("isb", "Isb64", "ArmStaticInst", "",
+                           ['IsSerializeAfter', 'IsSquashAfter'])
     header_output += BasicDeclare.subst(isbIop)
     decoder_output += BasicConstructor64.subst(isbIop)
     exec_output += BasicExecute.subst(isbIop)
 
-    dsbIop = InstObjParams("dsb", "Dsb64", "ArmStaticInst",
-                           "fault = std::make_shared<FlushPipe>();",
-                           ['IsMemBarrier', 'IsSerializeAfter'])
+    dsbIop = InstObjParams("dsb", "Dsb64", "ArmStaticInst", "",
+                           ['IsMemBarrier', 'IsSerializeAfter',
+                            'IsSquashAfter'])
     header_output += BasicDeclare.subst(dsbIop)
     decoder_output += BasicConstructor64.subst(dsbIop)
     exec_output += BasicExecute.subst(dsbIop)