x86: add tlb checkpointing

This patch adds checkpointing support to x86 tlb. It upgrades the
cpt_upgrader.py script so that previously created checkpoints can
be updated. It moves the checkpoint version to 6.

4 files changed, 35 insertions, 16 deletions

diff --git a/src/arch/x86/X86TLB.py b/src/arch/x86/X86TLB.py
index b652118ce..7f195f233 100644
--- a/src/arch/x86/X86TLB.py
+++ b/src/arch/x86/X86TLB.py
@@ -54,6 +54,6 @@ class X86TLB(BaseTLB):
     type = 'X86TLB'
     cxx_class = 'X86ISA::TLB'
     cxx_header = 'arch/x86/tlb.hh'
-    size = Param.Int(64, "TLB size")
+    size = Param.Unsigned(64, "TLB size")
     walker = Param.X86PagetableWalker(\
             X86PagetableWalker(), "page table walker")
diff --git a/src/arch/x86/pagetable.cc b/src/arch/x86/pagetable.cc
index 40d5e0984..a9ef18129 100644
--- a/src/arch/x86/pagetable.cc
+++ b/src/arch/x86/pagetable.cc
@@ -70,25 +70,14 @@ TlbEntry::unserialize(Checkpoint *cp, const std::string &section)
 {
     UNSERIALIZE_SCALAR(paddr);
     UNSERIALIZE_SCALAR(vaddr);
-    //
-    // The logBytes scalar variable replaced the previous size variable.
-    // The following code maintains backwards compatibility with previous
-    // checkpoints using the old size variable.
-    //
-    if (UNSERIALIZE_OPT_SCALAR(logBytes) == false) {
-        int size;
-        UNSERIALIZE_SCALAR(size);
-        logBytes = log2(size);
-    }
+    UNSERIALIZE_SCALAR(logBytes);
     UNSERIALIZE_SCALAR(writable);
     UNSERIALIZE_SCALAR(user);
     UNSERIALIZE_SCALAR(uncacheable);
     UNSERIALIZE_SCALAR(global);
     UNSERIALIZE_SCALAR(patBit);
     UNSERIALIZE_SCALAR(noExec);
-    if (UNSERIALIZE_OPT_SCALAR(lruSeq) == false) {
-        lruSeq = 0;
-    }
+    UNSERIALIZE_SCALAR(lruSeq);
 }
 
 }
diff --git a/src/arch/x86/tlb.cc b/src/arch/x86/tlb.cc
index 52cc3e0ee..087cfbadf 100644
--- a/src/arch/x86/tlb.cc
+++ b/src/arch/x86/tlb.cc
@@ -439,11 +439,42 @@ TLB::getWalker()
 void
 TLB::serialize(std::ostream &os)
 {
+    // Only store the entries in use.
+    uint32_t _size = size - freeList.size();
+    SERIALIZE_SCALAR(_size);
+    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++;
+        }
+    }
 }
 
 void
 TLB::unserialize(Checkpoint *cp, const std::string &section)
 {
+    // Do not allow to restore with a smaller tlb.
+    uint32_t _size;
+    UNSERIALIZE_SCALAR(_size);
+    if (_size > size) {
+        fatal("TLB size less than the one in checkpoint!");
+    }
+
+    UNSERIALIZE_SCALAR(lruSeq);
+
+    for (uint32_t x = 0; x < _size; x++) {
+        TlbEntry *newEntry = freeList.front();
+        freeList.pop_front();
+
+        newEntry->unserialize(cp, csprintf("%s.Entry%d", name(), x));
+        newEntry->trieHandle = trie.insert(newEntry->vaddr,
+            TlbEntryTrie::MaxBits - newEntry->logBytes, newEntry);
+    }
 }
 
 BaseMasterPort *
diff --git a/src/arch/x86/tlb.hh b/src/arch/x86/tlb.hh
index 4f0d58d5c..ea2d50ec2 100644
--- a/src/arch/x86/tlb.hh
+++ b/src/arch/x86/tlb.hh
@@ -95,12 +95,11 @@ namespace X86ISA
         void demapPage(Addr va, uint64_t asn);
 
       protected:
-        int size;
+        uint32_t size;
 
         TlbEntry * tlb;
 
         EntryList freeList;
-        EntryList entryList;
 
         TlbEntryTrie trie;
         uint64_t lruSeq;