Fix root symbol detection

Author: jbachorik

ddprof-lib/src/main/cpp/codeCache.cpp

@@ -190,7 +190,7 @@ CodeBlob *CodeCache::findBlobByAddress(const void *address) {
   return NULL;
 }
 
-const char *CodeCache::binarySearch(const void *address) {
+const void *CodeCache::binarySearch(const void *address, const char **name) {
   int low = 0;
   int high = _count - 1;
 
@@ -201,7 +201,10 @@ const char *CodeCache::binarySearch(const void *address) {
     } else if (_blobs[mid]._start > address) {
       high = mid - 1;
     } else {
-      return _blobs[mid]._name;
+      if (name != NULL) {
+        *name = _blobs[mid]._name;
+      }
+      return _blobs[mid]._start;
     }
   }
 
@@ -210,7 +213,12 @@ const char *CodeCache::binarySearch(const void *address) {
   // point beyond the function.
   if (low > 0 && (_blobs[low - 1]._start == _blobs[low - 1]._end ||
                   _blobs[low - 1]._end == address)) {
-    return _blobs[low - 1]._name;
+
+    if (name != NULL) {
+      *name = _blobs[low - 1]._name;
+    }
+
+    return _blobs[low - 1]._start;
   }
   return _name;
 }

ddprof-lib/src/main/cpp/codeCache.h

@@ -162,7 +162,7 @@ class CodeCache {
 
   CodeBlob *findBlob(const char *name);
   CodeBlob *findBlobByAddress(const void *address);
-  const char *binarySearch(const void *address);
+  const void *binarySearch(const void *address, const char **name);
   const void *findSymbol(const char *name);
   const void *findSymbolByPrefix(const char *prefix);
   const void *findSymbolByPrefix(const char *prefix, int prefix_len);

ddprof-lib/src/main/cpp/profiler.cpp

@@ -245,7 +245,11 @@ const char *Profiler::getLibraryName(const char *native_symbol) {
 
 const char *Profiler::findNativeMethod(const void *address) {
   CodeCache *lib = _libs->findLibraryByAddress(address);
-  return lib == NULL ? NULL : lib->binarySearch(address);
+  const char *name = NULL;
+  if (lib != NULL) {
+    lib->binarySearch(address, &name);
+  }
+  return name;
 }
 
 CodeBlob *Profiler::findRuntimeStub(const void *address) {

ddprof-lib/src/main/cpp/stackWalker.cpp

@@ -504,11 +504,12 @@ int StackWalker::walkVM(void* ucontext, ASGCT_CallFrame* frames, int max_depth,
         if (cc == NULL || !cc->contains(pc)) {
           cc = libraries->findLibraryByAddress(pc);
         }
-        const char *name = cc == NULL ? NULL : cc->binarySearch(pc);
+        const char *name = NULL;
+        const void* symbolPc = cc == NULL ? NULL : cc->binarySearch(pc, &name);
 
         fillFrame(frames[depth++], BCI_NATIVE_FRAME, name);
 
-        if (Symbols::isRootSymbol(pc)) {
+        if (symbolPc && Symbols::isRootSymbol(symbolPc)) {
           break;
         }
         prev_pc = pc;

ddprof-lib/src/main/cpp/symbols_linux.cpp

@@ -353,9 +353,6 @@ void ElfParser::loadSymbols(bool use_debug) {
 
 void ElfParser::addSymbol(const void *start, int length, const char *name, bool update_bounds) {
   _cc->add(start, length, name, update_bounds);
-  if (strstr(name, "thread_native_entry")) {
-    TEST_LOG("===> %s", name);
-  }
   for (int i = 0; i < LAST_ROOT_SYMBOL_KIND; i++) {
     if (!strcmp(root_symbol_table[i].name, name)) {
       TEST_LOG("Adding root symbol %s: %p", name, start);