MC: provide a workaround in the error msg seen on modern systems

[simgrid.git] / src / mc / inspect / ObjectInformation.cpp

diff --git a/src/mc/inspect/ObjectInformation.cpp b/src/mc/inspect/ObjectInformation.cpp
index 7d3229c..a2440d9 100644 (file)
--- a/src/mc/inspect/ObjectInformation.cpp
+++ b/src/mc/inspect/ObjectInformation.cpp
@@ -1,16 +1,17 @@
-/* Copyright (c) 2014-2019. The SimGrid Team.
- * All rights reserved.                                                     */
+/* Copyright (c) 2014-2019. The SimGrid Team. All rights reserved.          */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
 #include <cstdint>
-
+#include <sys/mman.h> // PROT_READ and friends
 #include <vector>
 
 #include "src/mc/inspect/Frame.hpp"
 #include "src/mc/inspect/ObjectInformation.hpp"
 #include "src/mc/inspect/Variable.hpp"
+#include "src/mc/mc_private.hpp"
+#include "xbt/file.hpp"
 
 namespace simgrid {
 namespace mc {
@@ -19,7 +20,7 @@ namespace mc {
  * (there is no offset) i.e.
  * \f$\text{virtual address} = \{dwarf address}\f$
  *
- * For a shared object, the addreses are offset from the begining
+ * For a shared object, the addresses are offset from the begining
  * of the shared object (the base address of the mapped shared
  * object must be used as offset
  * i.e. \f$\text{virtual address} = \text{shared object base address}
@@ -31,7 +32,7 @@ void* ObjectInformation::base_address() const
   if (this->executable())
     return nullptr;
 
-  // For an a shared-object (ET_DYN, including position-independant executables)
+  // For an a shared-object (ET_DYN, including position-independent executables)
   // the base address is its lowest address:
   void* result = this->start_exec;
   if (this->start_rw != nullptr && result > (void*)this->start_rw)
@@ -186,5 +187,75 @@ void ObjectInformation::remove_local_variable(const char* var_name, const char*
     simgrid::mc::remove_local_variable(entry.second, var_name, subprogram_name, entry.second);
 }
 
+/** @brief Fills the position of the segments (executable, read-only, read/write) */
+// TODO, use the ELF segment information for more robustness
+void find_object_address(std::vector<simgrid::xbt::VmMap> const& maps, simgrid::mc::ObjectInformation* result)
+{
+  const int PROT_RW = PROT_READ | PROT_WRITE;
+  const int PROT_RX = PROT_READ | PROT_EXEC;
+
+  std::string name = simgrid::xbt::Path(result->file_name).get_base_name();
+
+  for (size_t i = 0; i < maps.size(); ++i) {
+    simgrid::xbt::VmMap const& reg = maps[i];
+    if (maps[i].pathname.empty())
+      continue;
+    std::string map_basename = simgrid::xbt::Path(maps[i].pathname).get_base_name();
+    if (map_basename != name)
+      continue;
+
+    // This is the non-GNU_RELRO-part of the data segment:
+    if (reg.prot == PROT_RW) {
+      xbt_assert(not result->start_rw, "Multiple read-write segments for %s, not supported", maps[i].pathname.c_str());
+      result->start_rw = (char*)reg.start_addr;
+      result->end_rw   = (char*)reg.end_addr;
+
+      // The next VMA might be end of the data segment:
+      if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
+          maps[i + 1].start_addr == reg.end_addr)
+        result->end_rw = (char*)maps[i + 1].end_addr;
+    }
+
+    // This is the text segment:
+    else if (reg.prot == PROT_RX) {
+      xbt_assert(not result->start_exec, "Multiple executable segments for %s, not supported",
+                 maps[i].pathname.c_str());
+      result->start_exec = (char*)reg.start_addr;
+      result->end_exec   = (char*)reg.end_addr;
+
+      // The next VMA might be end of the data segment:
+      if (i + 1 < maps.size() && maps[i + 1].pathname.empty() && maps[i + 1].prot == PROT_RW &&
+          maps[i + 1].start_addr == reg.end_addr) {
+        result->start_rw = (char*)maps[i + 1].start_addr;
+        result->end_rw   = (char*)maps[i + 1].end_addr;
+      }
+    }
+
+    // This is the GNU_RELRO-part of the data segment:
+    else if (reg.prot == PROT_READ) {
+      xbt_assert(not result->start_ro,
+                 "Multiple read-only segments for %s, not supported. Compiling with the following may help: -Wl,-z "
+                 "-Wl,noseparate-code",
+                 maps[i].pathname.c_str());
+      result->start_ro = (char*)reg.start_addr;
+      result->end_ro   = (char*)reg.end_addr;
+    }
+  }
+
+  result->start = result->start_rw;
+  if ((const void*)result->start_ro < result->start)
+    result->start = result->start_ro;
+  if ((const void*)result->start_exec < result->start)
+    result->start = result->start_exec;
+
+  result->end = result->end_rw;
+  if (result->end_ro && (const void*)result->end_ro > result->end)
+    result->end = result->end_ro;
+  if (result->end_exec && (const void*)result->end_exec > result->end)
+    result->end = result->end_exec;
+
+  xbt_assert(result->start_exec || result->start_rw || result->start_ro);
+}
+
 } // namespace mc
 } // namespace simgrid