Add support to read aux vector values

Summary:
This is the second patch to improve module loading in a series that started here (where I explain the motivation and solution): https://reviews.llvm.org/D62499

I need to read the aux vector to know where the r_debug map with the loaded libraries are.
The AuxVector class was made generic so it could be reused between the POSIX-DYLD plugin and NativeProcess*. The class itself ended up in the ProcessUtility plugin.

Reviewers: clayborg, xiaobai, labath, JDevlieghere

Reviewed By: clayborg, labath, JDevlieghere

Subscribers: emaste, JDevlieghere, mgorny, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D62500

llvm-svn: 363098

2 files changed, 19 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
index a55dc41bed0..81d257e95e1 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -2082,3 +2082,18 @@ Status NativeProcessLinux::StopProcessorTracingOnThread(lldb::user_id_t traceid,
 
   return error;
 }
+
+llvm::Optional<uint64_t>
+NativeProcessLinux::GetAuxValue(enum AuxVector::EntryType type) {
+  if (m_aux_vector == nullptr) {
+    auto buffer_or_error = GetAuxvData();
+    if (!buffer_or_error)
+      return llvm::None;
+    DataExtractor auxv_data(buffer_or_error.get()->getBufferStart(),
+                            buffer_or_error.get()->getBufferSize(),
+                            GetByteOrder(), GetAddressByteSize());
+    m_aux_vector = llvm::make_unique<AuxVector>(auxv_data);
+  }
+
+  return m_aux_vector->GetAuxValue(type);
+}
diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
index 006ae000168..0a67af0a0a4 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
@@ -12,6 +12,7 @@
 #include <csignal>
 #include <unordered_set>
 
+#include "Plugins/Process/Utility/AuxVector.h"
 #include "lldb/Host/Debug.h"
 #include "lldb/Host/HostThread.h"
 #include "lldb/Host/linux/Support.h"
@@ -102,6 +103,8 @@ public:
     return getProcFile(GetID(), "auxv");
   }
 
+  llvm::Optional<uint64_t> GetAuxValue(enum AuxVector::EntryType type);
+
   lldb::user_id_t StartTrace(const TraceOptions &config,
                              Status &error) override;
 
@@ -132,6 +135,7 @@ protected:
 private:
   MainLoop::SignalHandleUP m_sigchld_handle;
   ArchSpec m_arch;
+  std::unique_ptr<AuxVector> m_aux_vector;
 
   LazyBool m_supports_mem_region = eLazyBoolCalculate;
   std::vector<std::pair<MemoryRegionInfo, FileSpec>> m_mem_region_cache;