1 files changed, 75 insertions, 0 deletions
diff --git a/trace-call.cc b/trace-call.cc
new file mode 100644
index 0000000..d154b4f
--- /dev/null
+++ b/trace-call.cc
@@ -0,0 +1,75 @@
+// Utility for finding call instruction coresponding to return address
+// Copyright (C) 2025  Nguyễn Gia Phong
+//
+// This file is part of taosc.
+//
+// Taosc is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Taosc is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with taosc.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "helpers.hh"
+
+// Dyninst headers
+#include <CFG.h>
+#include <CodeObject.h>
+
+#include <cassert>
+#include <iostream>
+#include <vector>
+
+int
+main (int argc, char** argv)
+{
+  Dyninst::ParseAPI::SymtabCodeSource cs {parse_args (argc, argv)};
+  Dyninst::ParseAPI::CodeObject co {&cs};
+  co.parse (); // parsed functions have same lifetime as co
+  while (!std::cin.eof ())
+    {
+      Dyninst::Address return_address;
+      std::cin >> std::hex >> return_address;
+      if (std::cin.fail ())
+        break;
+      auto* block = find_block (cs, co, return_address);
+      // Each function call creates an interprocedure edge,
+      // hence its basic block ends with the call site.
+      // The control flow then naturally goes to the next basic block
+      // starting with the return address.
+      if (block->start () != return_address)
+        die_for (return_address, "no block found with start address");
+      if (block->containingFuncs () < 1)
+        die_for (return_address, "no function containing return address");
+      std::vector <Dyninst::ParseAPI::Function*> functions;
+      block->getFuncs (functions);
+      Dyninst::Address call_address = 0;
+      for (auto* fun : functions)
+        for (auto* call_edge : fun->callEdges ())
+          {
+            auto* call_block = call_edge->src ();
+            auto* return_block = fun->getImmediatePostDominator (call_block);
+            if (return_block == nullptr || *return_block != *block)
+              continue;
+            if (call_address != 0)
+              {
+                assert (call_block->last () == call_address);
+                continue; // break if not for the assertion
+              }
+            call_address = call_block->last ();
+            std::cout << std::hex << call_address << '\n';
+          }
+      if (call_address == 0)
+        die_for (return_address, "no call found for return address");
+    }
+  if (std::cin.eof ())
+    return 0;
+  std::cerr << "invalid input\n";
+  return -1;
+}