sim: Refactor the serialization base class

Objects that are can be serialized are supposed to inherit from the
Serializable class. This class is meant to provide a unified API for
such objects. However, so far it has mainly been used by SimObjects
due to some fundamental design limitations. This changeset redesigns
to the serialization interface to make it more generic and hide the
underlying checkpoint storage. Specifically:

  * Add a set of APIs to serialize into a subsection of the current
    object. Previously, objects that needed this functionality would
    use ad-hoc solutions using nameOut() and section name
    generation. In the new world, an object that implements the
    interface has the methods serializeSection() and
    unserializeSection() that serialize into a named /subsection/ of
    the current object. Calling serialize() serializes an object into
    the current section.

  * Move the name() method from Serializable to SimObject as it is no
    longer needed for serialization. The fully qualified section name
    is generated by the main serialization code on the fly as objects
    serialize sub-objects.

  * Add a scoped ScopedCheckpointSection helper class. Some objects
    need to serialize data structures, that are not deriving from
    Serializable, into subsections. Previously, this was done using
    nameOut() and manual section name generation. To simplify this,
    this changeset introduces a ScopedCheckpointSection() helper
    class. When this class is instantiated, it adds a new /subsection/
    and subsequent serialization calls during the lifetime of this
    helper class happen inside this section (or a subsection in case
    of nested sections).

  * The serialize() call is now const which prevents accidental state
    manipulation during serialization. Objects that rely on modifying
    state can use the serializeOld() call instead. The default
    implementation simply calls serialize(). Note: The old-style calls
    need to be explicitly called using the
    serializeOld()/serializeSectionOld() style APIs. These are used by
    default when serializing SimObjects.

  * Both the input and output checkpoints now use their own named
    types. This hides underlying checkpoint implementation from
    objects that need checkpointing and makes it easier to change the
    underlying checkpoint storage code.

10 files changed, 69 insertions, 68 deletions

diff --git a/src/arch/x86/interrupts.cc b/src/arch/x86/interrupts.cc
index 171e8a1c5..556cdda37 100644
--- a/src/arch/x86/interrupts.cc
+++ b/src/arch/x86/interrupts.cc
@@ -729,7 +729,7 @@ X86ISA::Interrupts::updateIntrInfo(ThreadContext *tc)
 }
 
 void
-X86ISA::Interrupts::serialize(std::ostream &os)
+X86ISA::Interrupts::serialize(CheckpointOut &cp) const
 {
     SERIALIZE_ARRAY(regs, NUM_APIC_REGS);
     SERIALIZE_SCALAR(pendingSmi);
@@ -754,7 +754,7 @@ X86ISA::Interrupts::serialize(std::ostream &os)
 }
 
 void
-X86ISA::Interrupts::unserialize(Checkpoint *cp, const std::string &section)
+X86ISA::Interrupts::unserialize(CheckpointIn &cp)
 {
     UNSERIALIZE_ARRAY(regs, NUM_APIC_REGS);
     UNSERIALIZE_SCALAR(pendingSmi);
diff --git a/src/arch/x86/interrupts.hh b/src/arch/x86/interrupts.hh
index b584c234b..272cfea44 100644
--- a/src/arch/x86/interrupts.hh
+++ b/src/arch/x86/interrupts.hh
@@ -293,9 +293,8 @@ class Interrupts : public BasicPioDevice, IntDevice
     /*
      * Serialization.
      */
-
-    virtual void serialize(std::ostream &os);
-    virtual void unserialize(Checkpoint *cp, const std::string &section);
+    void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+    void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
 
     /*
      * Old functions needed for compatability but which will be phased out
diff --git a/src/arch/x86/isa.cc b/src/arch/x86/isa.cc
index f9b99db0f..213a9e2e3 100644
--- a/src/arch/x86/isa.cc
+++ b/src/arch/x86/isa.cc
@@ -409,13 +409,13 @@ ISA::setMiscReg(int miscReg, MiscReg val, ThreadContext * tc)
 }
 
 void
-ISA::serialize(std::ostream & os)
+ISA::serialize(CheckpointOut &cp) const
 {
     SERIALIZE_ARRAY(regVal, NumMiscRegs);
 }
 
 void
-ISA::unserialize(Checkpoint * cp, const std::string & section)
+ISA::unserialize(CheckpointIn &cp)
 {
     UNSERIALIZE_ARRAY(regVal, NumMiscRegs);
     updateHandyM5Reg(regVal[MISCREG_EFER],
diff --git a/src/arch/x86/isa.hh b/src/arch/x86/isa.hh
index a82b4ae2f..88f4980ae 100644
--- a/src/arch/x86/isa.hh
+++ b/src/arch/x86/isa.hh
@@ -97,8 +97,9 @@ namespace X86ISA
             return reg;
         }
 
-        void serialize(std::ostream &os);
-        void unserialize(Checkpoint *cp, const std::string &section);
+        void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+        void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
+
         void startup(ThreadContext *tc);
 
         /// Explicitly import the otherwise hidden startup
diff --git a/src/arch/x86/pagetable.cc b/src/arch/x86/pagetable.cc
index cd4df42e7..4e8c39eb9 100644
--- a/src/arch/x86/pagetable.cc
+++ b/src/arch/x86/pagetable.cc
@@ -45,15 +45,22 @@
 namespace X86ISA
 {
 
+TlbEntry::TlbEntry()
+    : paddr(0), vaddr(0), logBytes(0), writable(0),
+      user(true), uncacheable(0), global(false), patBit(0),
+      noExec(false), lruSeq(0)
+{
+}
+
 TlbEntry::TlbEntry(Addr asn, Addr _vaddr, Addr _paddr,
                    bool uncacheable, bool read_only) :
     paddr(_paddr), vaddr(_vaddr), logBytes(PageShift), writable(!read_only),
     user(true), uncacheable(uncacheable), global(false), patBit(0),
-    noExec(false)
+    noExec(false), lruSeq(0)
 {}
 
 void
-TlbEntry::serialize(std::ostream &os)
+TlbEntry::serialize(CheckpointOut &cp) const
 {
     SERIALIZE_SCALAR(paddr);
     SERIALIZE_SCALAR(vaddr);
@@ -68,7 +75,7 @@ TlbEntry::serialize(std::ostream &os)
 }
 
 void
-TlbEntry::unserialize(Checkpoint *cp, const std::string &section)
+TlbEntry::unserialize(CheckpointIn &cp)
 {
     UNSERIALIZE_SCALAR(paddr);
     UNSERIALIZE_SCALAR(vaddr);
diff --git a/src/arch/x86/pagetable.hh b/src/arch/x86/pagetable.hh
index 639815893..3345366d0 100644
--- a/src/arch/x86/pagetable.hh
+++ b/src/arch/x86/pagetable.hh
@@ -97,7 +97,7 @@ namespace X86ISA
     EndBitUnion(PageTableEntry)
 
 
-    struct TlbEntry
+    struct TlbEntry : public Serializable
     {
         // The base of the physical page.
         Addr paddr;
@@ -130,7 +130,7 @@ namespace X86ISA
 
         TlbEntry(Addr asn, Addr _vaddr, Addr _paddr,
                  bool uncacheable, bool read_only);
-        TlbEntry() {}
+        TlbEntry();
 
         void
         updateVaddr(Addr new_vaddr)
@@ -149,8 +149,8 @@ namespace X86ISA
             return (1 << logBytes);
         }
 
-        void serialize(std::ostream &os);
-        void unserialize(Checkpoint *cp, const std::string &section);
+        void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+        void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
     };
 
     /** The size of each level of the page table expressed in base 2
diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index 86e051deb..d0e77bc9b 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -62,13 +62,12 @@
 
 namespace X86ISA {
 
-TLB::TLB(const Params *p) : BaseTLB(p), configAddress(0), size(p->size),
-    lruSeq(0)
+TLB::TLB(const Params *p)
+    : BaseTLB(p), configAddress(0), size(p->size),
+      tlb(size), lruSeq(0)
 {
     if (!size)
         fatal("TLBs must have a non-zero size.\n");
-    tlb = new TlbEntry[size];
-    std::memset(tlb, 0, sizeof(TlbEntry) * size);
 
     for (int x = 0; x < size; x++) {
         tlb[x].trieHandle = NULL;
@@ -451,7 +450,7 @@ TLB::getWalker()
 }
 
 void
-TLB::serialize(std::ostream &os)
+TLB::serialize(CheckpointOut &cp) const
 {
     // Only store the entries in use.
     uint32_t _size = size - freeList.size();
@@ -459,18 +458,14 @@ TLB::serialize(std::ostream &os)
     SERIALIZE_SCALAR(lruSeq);
 
     uint32_t _count = 0;
-
     for (uint32_t x = 0; x < size; x++) {
-        if (tlb[x].trieHandle != NULL) {
-            os << "\n[" << csprintf("%s.Entry%d", name(), _count) << "]\n";
-            tlb[x].serialize(os);
-            _count++;
-        }
+        if (tlb[x].trieHandle != NULL)
+            tlb[x].serializeSection(cp, csprintf("Entry%d", _count++));
     }
 }
 
 void
-TLB::unserialize(Checkpoint *cp, const std::string &section)
+TLB::unserialize(CheckpointIn &cp)
 {
     // Do not allow to restore with a smaller tlb.
     uint32_t _size;
@@ -485,7 +480,7 @@ TLB::unserialize(Checkpoint *cp, const std::string &section)
         TlbEntry *newEntry = freeList.front();
         freeList.pop_front();
 
-        newEntry->unserialize(cp, csprintf("%s.Entry%d", name(), x));
+        newEntry->unserializeSection(cp, csprintf("Entry%d", x));
         newEntry->trieHandle = trie.insert(newEntry->vaddr,
             TlbEntryTrie::MaxBits - newEntry->logBytes, newEntry);
     }
diff --git a/src/arch/x86/tlb.hh b/src/arch/x86/tlb.hh
index 77f9fc49d..83ec7cc59 100644
--- a/src/arch/x86/tlb.hh
+++ b/src/arch/x86/tlb.hh
@@ -98,7 +98,7 @@ namespace X86ISA
       protected:
         uint32_t size;
 
-        TlbEntry * tlb;
+        std::vector<TlbEntry> tlb;
 
         EntryList freeList;
 
@@ -148,8 +148,8 @@ namespace X86ISA
         TlbEntry * insert(Addr vpn, TlbEntry &entry);
 
         // Checkpointing
-        virtual void serialize(std::ostream &os);
-        virtual void unserialize(Checkpoint *cp, const std::string &section);
+        void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
+        void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
 
         /**
          * Get the table walker master port. This is used for
diff --git a/src/arch/x86/types.cc b/src/arch/x86/types.cc
index 830a131e5..a960205b5 100644
--- a/src/arch/x86/types.cc
+++ b/src/arch/x86/types.cc
@@ -36,69 +36,68 @@ using namespace std;
 
 template <>
 void
-paramOut(ostream &os, const string &name, ExtMachInst const &machInst)
+paramOut(CheckpointOut &cp, const string &name, ExtMachInst const &machInst)
 {
     // Prefixes
-    paramOut(os, name + ".legacy", (uint8_t)machInst.legacy);
-    paramOut(os, name + ".rex", (uint8_t)machInst.rex);
+    paramOut(cp, name + ".legacy", (uint8_t)machInst.legacy);
+    paramOut(cp, name + ".rex", (uint8_t)machInst.rex);
 
     // Opcode
-    paramOut(os, name + ".opcode.type", (uint8_t)machInst.opcode.type);
-    paramOut(os, name + ".opcode.op", (uint8_t)machInst.opcode.op);
+    paramOut(cp, name + ".opcode.type", (uint8_t)machInst.opcode.type);
+    paramOut(cp, name + ".opcode.op", (uint8_t)machInst.opcode.op);
 
     // Modifier bytes
-    paramOut(os, name + ".modRM", (uint8_t)machInst.modRM);
-    paramOut(os, name + ".sib", (uint8_t)machInst.sib);
+    paramOut(cp, name + ".modRM", (uint8_t)machInst.modRM);
+    paramOut(cp, name + ".sib", (uint8_t)machInst.sib);
 
     // Immediate fields
-    paramOut(os, name + ".immediate", machInst.immediate);
-    paramOut(os, name + ".displacement", machInst.displacement);
+    paramOut(cp, name + ".immediate", machInst.immediate);
+    paramOut(cp, name + ".displacement", machInst.displacement);
 
     // Sizes
-    paramOut(os, name + ".opSize", machInst.opSize);
-    paramOut(os, name + ".addrSize", machInst.addrSize);
-    paramOut(os, name + ".stackSize", machInst.stackSize);
-    paramOut(os, name + ".dispSize", machInst.dispSize);
+    paramOut(cp, name + ".opSize", machInst.opSize);
+    paramOut(cp, name + ".addrSize", machInst.addrSize);
+    paramOut(cp, name + ".stackSize", machInst.stackSize);
+    paramOut(cp, name + ".dispSize", machInst.dispSize);
 
     // Mode
-    paramOut(os, name + ".mode", (uint8_t)machInst.mode);
+    paramOut(cp, name + ".mode", (uint8_t)machInst.mode);
 }
 
 template <>
 void
-paramIn(Checkpoint *cp, const string &section,
-        const string &name, ExtMachInst &machInst)
+paramIn(CheckpointIn &cp, const string &name, ExtMachInst &machInst)
 {
     uint8_t temp8;
     // Prefixes
-    paramIn(cp, section, name + ".legacy", temp8);
+    paramIn(cp, name + ".legacy", temp8);
     machInst.legacy = temp8;
-    paramIn(cp, section, name + ".rex", temp8);
+    paramIn(cp, name + ".rex", temp8);
     machInst.rex = temp8;
 
     // Opcode
-    paramIn(cp, section, name + ".opcode.type", temp8);
+    paramIn(cp, name + ".opcode.type", temp8);
     machInst.opcode.type = (OpcodeType)temp8;
-    paramIn(cp, section, name + ".opcode.op", temp8);
+    paramIn(cp, name + ".opcode.op", temp8);
     machInst.opcode.op = temp8;
 
     // Modifier bytes
-    paramIn(cp, section, name + ".modRM", temp8);
+    paramIn(cp, name + ".modRM", temp8);
     machInst.modRM = temp8;
-    paramIn(cp, section, name + ".sib", temp8);
+    paramIn(cp, name + ".sib", temp8);
     machInst.sib = temp8;;
 
     // Immediate fields
-    paramIn(cp, section, name + ".immediate", machInst.immediate);
-    paramIn(cp, section, name + ".displacement", machInst.displacement);
+    paramIn(cp, name + ".immediate", machInst.immediate);
+    paramIn(cp, name + ".displacement", machInst.displacement);
 
     // Sizes
-    paramIn(cp, section, name + ".opSize", machInst.opSize);
-    paramIn(cp, section, name + ".addrSize", machInst.addrSize);
-    paramIn(cp, section, name + ".stackSize", machInst.stackSize);
-    paramIn(cp, section, name + ".dispSize", machInst.dispSize);
+    paramIn(cp, name + ".opSize", machInst.opSize);
+    paramIn(cp, name + ".addrSize", machInst.addrSize);
+    paramIn(cp, name + ".stackSize", machInst.stackSize);
+    paramIn(cp, name + ".dispSize", machInst.dispSize);
 
     // Mode
-    paramIn(cp, section, name + ".mode", temp8);
+    paramIn(cp, name + ".mode", temp8);
     machInst.mode = temp8;
 }
diff --git a/src/arch/x86/types.hh b/src/arch/x86/types.hh
index dd60c0aec..23d60020b 100644
--- a/src/arch/x86/types.hh
+++ b/src/arch/x86/types.hh
@@ -276,16 +276,16 @@ namespace X86ISA
         }
 
         void
-        serialize(std::ostream &os)
+        serialize(CheckpointOut &cp) const
         {
-            Base::serialize(os);
+            Base::serialize(cp);
             SERIALIZE_SCALAR(_size);
         }
 
         void
-        unserialize(Checkpoint *cp, const std::string &section)
+        unserialize(CheckpointIn &cp)
         {
-            Base::unserialize(cp, section);
+            Base::unserialize(cp);
             UNSERIALIZE_SCALAR(_size);
         }
     };
@@ -314,11 +314,11 @@ __hash_namespace_end
 // and UNSERIALIZE_SCALAR.
 template <>
 void
-paramOut(std::ostream &os, const std::string &name,
+paramOut(CheckpointOut &cp, const std::string &name,
          const X86ISA::ExtMachInst &machInst);
 template <>
 void
-paramIn(Checkpoint *cp, const std::string &section,
-        const std::string &name, X86ISA::ExtMachInst &machInst);
+paramIn(CheckpointIn &cp, const std::string &name,
+        X86ISA::ExtMachInst &machInst);
 
 #endif // __ARCH_X86_TYPES_HH__