[Lldb-commits] [lldb] r356108 - Reorder the operations in

[Jason Molenda via lldb-commits]

Author: jmolenda
Date: Wed Mar 13 16:34:20 2019
New Revision: 356108

URL: http://llvm.org/viewvc/llvm-project?rev=356108&view=rev
Log:
Reorder the operations in
DynamicLoaderDarwinKernel::KextImageInfo::LoadImageUsingMemoryModule a
bit so that we only read the binaries out of memory once we've
determined that we can find a real binary on the local system.  

Previously, lldb would read all of the kext binaries out of memory
and then determine if it had the local copy.  The kext table gives
us most the information we need (address, name, uuid) so lldb only
needs the actual in-memory load commands when it comes time to set
the section load addresses.  Delay reading until that point for all
the kexts.

NFC; doing the operations in a different order.


<rdar://problem/41181173> 

Modified:
    lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp

Modified: lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp?rev=356108&r1=356107&r2=356108&view=diff
==============================================================================
--- lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp (original)
+++ lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp Wed Mar 13 16:34:20 2019
@@ -766,24 +766,24 @@ bool DynamicLoaderDarwinKernel::KextImag
 
   Target &target = process->GetTarget();
 
-  // If we don't have / can't create a memory module for this kext, don't try
-  // to load it - we won't have the correct segment load addresses.
-  if (!ReadMemoryModule(process)) {
-    Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
-    if (log)
-      log->Printf("Unable to read '%s' from memory at address 0x%" PRIx64
-                  " to get the segment load addresses.",
-                  m_name.c_str(), m_load_address);
-    return false;
+  // kexts will have a uuid from the table.
+  // for the kernel, we'll need to read the load commands out of memory to get it.
+  if (m_uuid.IsValid() == false) {
+    if (ReadMemoryModule(process) == false) {
+      Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
+      if (log)
+        log->Printf("Unable to read '%s' from memory at address 0x%" PRIx64
+                    " to get the segment load addresses.",
+                    m_name.c_str(), m_load_address);
+      return false;
+    }
   }
 
-  bool uuid_is_valid = m_uuid.IsValid();
-
-  if (IsKernel() && uuid_is_valid && m_memory_module_sp.get()) {
+  if (IsKernel() && m_uuid.IsValid()) {
     Stream *s = target.GetDebugger().GetOutputFile().get();
     if (s) {
       s->Printf("Kernel UUID: %s\n",
-                m_memory_module_sp->GetUUID().GetAsString().c_str());
+                m_uuid.GetAsString().c_str());
       s->Printf("Load Address: 0x%" PRIx64 "\n", m_load_address);
     }
   }
@@ -795,7 +795,7 @@ bool DynamicLoaderDarwinKernel::KextImag
     m_module_sp = target_images.FindModule(m_uuid);
 
     // Search for the kext on the local filesystem via the UUID
-    if (!m_module_sp && uuid_is_valid) {
+    if (!m_module_sp && m_uuid.IsValid()) {
       ModuleSpec module_spec;
       module_spec.GetUUID() = m_uuid;
       module_spec.GetArchitecture() = target.GetArchitecture();
@@ -857,13 +857,7 @@ bool DynamicLoaderDarwinKernel::KextImag
     // images. If we also have a memory module, require that they have matching
     // UUIDs
     if (m_module_sp) {
-      bool uuid_match_ok = true;
-      if (m_memory_module_sp) {
-        if (m_module_sp->GetUUID() != m_memory_module_sp->GetUUID()) {
-          uuid_match_ok = false;
-        }
-      }
-      if (uuid_match_ok) {
+      if (m_uuid.IsValid() && m_module_sp->GetUUID() == m_uuid) {
         target.GetImages().AppendIfNeeded(m_module_sp);
         if (IsKernel() &&
             target.GetExecutableModulePointer() != m_module_sp.get()) {
@@ -873,6 +867,11 @@ bool DynamicLoaderDarwinKernel::KextImag
     }
   }
 
+  // If we've found a binary, read the load commands out of memory so we
+  // can set the segment load addresses.
+  if (m_module_sp)
+    ReadMemoryModule (process);
+
   static ConstString g_section_name_LINKEDIT("__LINKEDIT");
 
   if (m_memory_module_sp && m_module_sp) {