From b12a136cddb5fea6e1a502bbc9fd815b7818a30c Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmolenda@apple.com>
Date: Sat, 20 Dec 2014 03:12:51 +0000
Subject: [PATCH] Re-enable compact unwind use on Mac platforms. When lldb has
 a binary with protected section contents, don't use the on-disk
 representation of that compact uwnind -- read it only out of live memory
 where it has been decrypted.

llvm-svn: 224670
---
 lldb/include/lldb/Symbol/CompactUnwindInfo.h |  7 +--
 lldb/source/Symbol/CompactUnwindInfo.cpp     | 49 ++++++++++++++------
 2 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/lldb/include/lldb/Symbol/CompactUnwindInfo.h b/lldb/include/lldb/Symbol/CompactUnwindInfo.h
index eb0e020d1b44..911c2b45bbb1 100644
--- a/lldb/include/lldb/Symbol/CompactUnwindInfo.h
+++ b/lldb/include/lldb/Symbol/CompactUnwindInfo.h
@@ -42,7 +42,7 @@ public:
     GetUnwindPlan (Target &target, Address addr, UnwindPlan& unwind_plan);
 
     bool
-    IsValid ();
+    IsValid (const lldb::ProcessSP &process_sp);
 
 private:
 
@@ -104,7 +104,7 @@ private:
     };
 
     void
-    ScanIndex();
+    ScanIndex(const lldb::ProcessSP &process_sp);
 
     bool
     GetCompactUnwindInfoForFunction (Target &target, Address address, FunctionInfo &unwind_info);
@@ -126,7 +126,8 @@ private:
 
     ObjectFile                  &m_objfile;
     lldb::SectionSP             m_section_sp;
-
+    lldb::DataBufferSP          m_section_contents_if_encrypted; // if the binary is encrypted, read the sect contents
+                                                                 // out of live memory and cache them here
     Mutex                       m_mutex;
     std::vector<UnwindIndex>    m_indexes;
 
diff --git a/lldb/source/Symbol/CompactUnwindInfo.cpp b/lldb/source/Symbol/CompactUnwindInfo.cpp
index 4635443a916d..09c0ac7083e5 100644
--- a/lldb/source/Symbol/CompactUnwindInfo.cpp
+++ b/lldb/source/Symbol/CompactUnwindInfo.cpp
@@ -12,14 +12,16 @@
 // C++ Includes
 #include <algorithm>
 
-#include "lldb/Core/Log.h"
-#include "lldb/Core/Section.h"
 #include "lldb/Core/ArchSpec.h"
+#include "lldb/Core/Log.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/Section.h"
+#include "lldb/Core/Section.h"
 #include "lldb/Symbol/CompactUnwindInfo.h"
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Symbol/UnwindPlan.h"
+#include "lldb/Target/Process.h"
+#include "lldb/Target/Target.h"
 
 #include "llvm/Support/MathExtras.h"
 
@@ -124,6 +126,7 @@ namespace lldb_private {
 CompactUnwindInfo::CompactUnwindInfo(ObjectFile& objfile, SectionSP& section_sp) :
     m_objfile (objfile),
     m_section_sp (section_sp),
+    m_section_contents_if_encrypted (),
     m_mutex (),
     m_indexes (),
     m_indexes_computed (eLazyBoolCalculate),
@@ -145,7 +148,7 @@ CompactUnwindInfo::~CompactUnwindInfo()
 bool
 CompactUnwindInfo::GetUnwindPlan (Target &target, Address addr, UnwindPlan& unwind_plan)
 {
-    if (!IsValid ())
+    if (!IsValid (target.GetProcessSP()))
     {
         return false;
     }
@@ -173,21 +176,21 @@ CompactUnwindInfo::GetUnwindPlan (Target &target, Address addr, UnwindPlan& unwi
 }
 
 bool
-CompactUnwindInfo::IsValid ()
+CompactUnwindInfo::IsValid (const ProcessSP &process_sp)
 {
-    if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
+    if (m_section_sp.get() == nullptr)
         return false;
 
     if (m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed)
         return true;
 
-    ScanIndex ();
+    ScanIndex (process_sp);
 
     return m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed;
 }
 
 void
-CompactUnwindInfo::ScanIndex ()
+CompactUnwindInfo::ScanIndex (const ProcessSP &process_sp)
 {
     Mutex::Locker locker(m_mutex);
     if (m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed)
@@ -201,7 +204,30 @@ CompactUnwindInfo::ScanIndex ()
 
     if (m_unwindinfo_data_computed == false)
     {
-        m_objfile.ReadSectionData (m_section_sp.get(), m_unwindinfo_data);
+        if (m_section_sp->IsEncrypted())
+        {
+            // Can't get section contents of a protected/encrypted section until we have a live
+            // process and can read them out of memory.
+            if (process_sp.get() == nullptr)
+                return;
+            m_section_contents_if_encrypted.reset (new DataBufferHeap (m_section_sp->GetByteSize(), 0));
+            Error error;
+            if (process_sp->ReadMemory (
+                        m_section_sp->GetLoadBaseAddress (&process_sp->GetTarget()), 
+                        m_section_contents_if_encrypted->GetBytes(), 
+                        m_section_sp->GetByteSize(), error) == m_section_sp->GetByteSize() && error.Success())
+            {
+                m_unwindinfo_data.SetAddressByteSize (process_sp->GetTarget().GetArchitecture().GetAddressByteSize());
+                m_unwindinfo_data.SetByteOrder (process_sp->GetTarget().GetArchitecture().GetByteOrder());
+                m_unwindinfo_data.SetData (m_section_contents_if_encrypted, 0);
+            }
+        }
+        else
+        {
+            m_objfile.ReadSectionData (m_section_sp.get(), m_unwindinfo_data);
+        }
+        if (m_unwindinfo_data.GetByteSize() != m_section_sp->GetByteSize())
+            return;
         m_unwindinfo_data_computed = true;
     }
 
@@ -409,14 +435,9 @@ CompactUnwindInfo::GetCompactUnwindInfoForFunction (Target &target, Address addr
     unwind_info.lsda_address.Clear();
     unwind_info.personality_ptr_address.Clear();
 
-    if (!IsValid ())
+    if (!IsValid (target.GetProcessSP()))
         return false;
 
-    // FIXME looking into a problem with getting the wrong compact unwind entry for
-    // _CFRunLoopRun from CoreFoundation in a live process; disabling the Compact 
-    // Unwind plans until I get to the bottom of what's going on there.
-    return false;
-
     addr_t text_section_file_address = LLDB_INVALID_ADDRESS;
     SectionList *sl = m_objfile.GetSectionList ();
     if (sl)