Add support for sampled PC profiling to FullCPU.

Simple text list of symbol (or address) and count
will be dumped to m5prof.<cpu-name> if the cpu's
pc_sample_interval param is set.

SConscript:
    Add cpu/full_cpu/pc_sample_profile.cc
base/callback.hh:
    Add a comment about MakeCallback.
    Fix type in another comment.
base/loader/symtab.cc:
    Revamp findNearestSymbol() to provide addresses of both
    nearest symbols (preceding and following) as well as
    string for former.

    Move global definition of debugSymbolTable here too.
base/loader/symtab.hh:
    Revamp findNearestSymbol() to provide addresses of both
    nearest symbols (preceding and following) as well as
    string for former.

    Move global declaration of debugSymbolTable here too.
cpu/exetrace.cc:
    Use new findNearestSymbol() interface for trace symbols.
kern/linux/linux_system.cc:
sim/system.cc:
    Remove extern of debugSymbolTable (now in symtab.hh)
sim/process.cc:
    Initialize debugSymbolTable if binary has a symbol table.

--HG--
extra : convert_revision : 0b5393dc39c40ac88c953684708f1125da550671

2 files changed, 39 insertions, 17 deletions

diff --git a/base/loader/symtab.cc b/base/loader/symtab.cc
index f6abf7e3d..c018ae4f8 100644
--- a/base/loader/symtab.cc
+++ b/base/loader/symtab.cc
@@ -38,6 +38,8 @@
 
 using namespace std;
 
+SymbolTable *debugSymbolTable = NULL;
+
 bool
 SymbolTable::insert(Addr address, string symbol)
 {
@@ -95,26 +97,20 @@ SymbolTable::load(const string &filename)
 }
 
 bool
-SymbolTable::findNearestSymbol(Addr address, string &symbol) const
+SymbolTable::findNearestSymbol(Addr address, string &symbol,
+                               Addr &sym_address, Addr &next_sym_address) const
 {
-    ATable::const_iterator i = addrTable.lower_bound(address);
-
-    // check for PALCode
-    if (address & 0x1)
-        return false;
+    // find first key *larger* than desired address
+    ATable::const_iterator i = addrTable.upper_bound(address);
 
-    // first check for the end
-    if (i == addrTable.end())
-        i--;
-    else if (i == addrTable.begin() && (*i).first != address)
+    // if very first key is larger, we're out of luck
+    if (i == addrTable.begin())
         return false;
-    else if ((*i).first != address)
-        i--;
-
-    symbol = (*i).second;
 
-    if (address != (*i).first)
-        symbol += csprintf("+%d", address - (*i).first);
+    next_sym_address = i->first;
+    --i;
+    sym_address = i->first;
+    symbol = i->second;
 
     return true;
 }
diff --git a/base/loader/symtab.hh b/base/loader/symtab.hh
index 48230c7a2..df3783991 100644
--- a/base/loader/symtab.hh
+++ b/base/loader/symtab.hh
@@ -49,7 +49,27 @@ class SymbolTable
     bool insert(Addr address, std::string symbol);
     bool load(const std::string &file);
 
-    bool findNearestSymbol(Addr address, std::string &symbol) const;
+    /// Find the nearest symbol equal to or less than the supplied
+    /// address (e.g., the label for the enclosing function).
+    /// @param address The address to look up.
+    /// @param symbol  Return reference for symbol string.
+    /// @param sym_address Return reference for symbol address.
+    /// @param next_sym_address Address of following symbol (for
+    /// determining valid range of symbol).
+    /// @retval True if a symbol was found.
+    bool findNearestSymbol(Addr address, std::string &symbol,
+                           Addr &sym_address, Addr &next_sym_address) const;
+
+    /// Overload for findNearestSymbol() for callers who don't care
+    /// about next_sym_address.
+    bool findNearestSymbol(Addr address, std::string &symbol,
+                           Addr &sym_address) const
+    {
+        Addr dummy;
+        return findNearestSymbol(address, symbol, sym_address, dummy);
+    }
+
+
     bool findSymbol(Addr address, std::string &symbol) const;
     bool findAddress(const std::string &symbol, Addr &address) const;
 
@@ -57,4 +77,10 @@ class SymbolTable
     Addr find(const std::string &symbol) const;
 };
 
+/// Global unified debugging symbol table (for target).  Conceptually
+/// there should be one of these per System object for full system,
+/// and per Process object for non-full-system, but so far one big
+/// global one has worked well enough.
+extern SymbolTable *debugSymbolTable;
+
 #endif // __SYMTAB_HH__