sim: Fix Mempool overrides during checkpoint

This patch fixes the problem during checkpoing where the mempool is not
restored, but using only the one specified in the config file as a new
execution.
In order to fix that this changes modifyies the serialize/unserialize
functions for mempools and create new funcionts on se_workload to make
sure mempools ends up in the m5.cpt.
We change as well the unserialize mempool function to update
according the checkpoint file so the execution starts with the same
free pages and free pointers.

JIRA: https://gem5.atlassian.net/browse/GEM5-1191

Change-Id: I289bf91eb4f01d9c01a31a39b968e30f8b8d2bdc
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56969
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/sim/mem_pool.cc

@@ -169,6 +169,7 @@ MemPools::freeMemSize(int pool_id) const
 void
 MemPools::serialize(CheckpointOut &cp) const
 {
+    ScopedCheckpointSection sec(cp, "mempools");
     int num_pools = pools.size();
     SERIALIZE_SCALAR(num_pools);
 
@@ -179,6 +180,10 @@ MemPools::serialize(CheckpointOut &cp) const
 void
 MemPools::unserialize(CheckpointIn &cp)
 {
+    // Delete previous mem_pools
+    pools.clear();
+
+    ScopedCheckpointSection sec(cp, "mempools");
     int num_pools = 0;
     UNSERIALIZE_SCALAR(num_pools);
 

src/sim/process.cc

@@ -388,6 +388,7 @@ Process::unserialize(CheckpointIn &cp)
     memState->unserialize(cp);
     pTable->unserialize(cp);
     fds->unserialize(cp);
+
     /**
      * Checkpoints for pipes, device drivers or sockets currently
      * do not work. Need to come back and fix them at a later date.

src/sim/se_workload.cc

@@ -53,6 +53,18 @@ SEWorkload::setSystem(System *sys)
     memPools.populate(memories);
 }
 
+void
+SEWorkload::serialize(CheckpointOut &cp) const
+{
+    memPools.serialize(cp);
+}
+
+void
+SEWorkload::unserialize(CheckpointIn &cp)
+{
+    memPools.unserialize(cp);
+}
+
 void
 SEWorkload::syscall(ThreadContext *tc)
 {

src/sim/se_workload.hh

@@ -81,6 +81,9 @@ class SEWorkload : public Workload
         panic("No workload symbol table for syscall emulation mode.");
     }
 
+    void serialize(CheckpointOut &cp) const override;
+    void unserialize(CheckpointIn &cp) override;
+
     void syscall(ThreadContext *tc) override;
 
     // For now, assume the only type of events are system calls.