Add debug_frame section support

Summary:
This is a beefed-up version of D33504, which adds support for dwarf 4
debug_frame section format.

The main difference here is that the decision whether to use eh_frame or
debug_frame is done on a per-function basis instead of per-object file.
This is necessary because one module can contain both sections (for
example, the start files added by the linker will typically pull in
eh_frame), but we want to be able to access both, for maximum
information.

I also add unit test for parsing various CFI formats (eh_frame,
debug_frame v3 and debug_frame v4).

Reviewers: jasonmolenda, clayborg

Subscribers: mgorny, aprantl, abidh, lldb-commits, tatyana-krasnukha

Differential Revision: https://reviews.llvm.org/D34613

llvm-svn: 306397

lldb/include/lldb/Symbol/DWARFCallFrameInfo.h

@@ -37,7 +37,7 @@ class DWARFCallFrameInfo {
   DWARFCallFrameInfo(ObjectFile &objfile, lldb::SectionSP &section,
                      lldb::RegisterKind reg_kind, bool is_eh_frame);
 
-  ~DWARFCallFrameInfo();
+  ~DWARFCallFrameInfo() = default;
 
   // Locate an AddressRange that includes the provided Address in this
   // object's eh_frame/debug_info
@@ -74,12 +74,20 @@ class DWARFCallFrameInfo {
 
 private:
   enum { CFI_AUG_MAX_SIZE = 8, CFI_HEADER_SIZE = 8 };
+  enum CFIVersion {
+    CFI_VERSION1 = 1, // DWARF v.2
+    CFI_VERSION3 = 3, // DWARF v.3
+    CFI_VERSION4 = 4  // DWARF v.4, v.5
+  };
 
   struct CIE {
     dw_offset_t cie_offset;
     uint8_t version;
     char augmentation[CFI_AUG_MAX_SIZE]; // This is typically empty or very
                                          // short.
+    uint8_t address_size = sizeof(uint32_t); // The size of a target address.
+    uint8_t segment_size = 0;                // The size of a segment selector.
+
     uint32_t code_align;
     int32_t data_align;
     uint32_t return_addr_reg_num;

lldb/include/lldb/Symbol/FuncUnwinders.h

@@ -99,6 +99,13 @@ class FuncUnwinders {
                                                    Thread &thread,
                                                    int current_offset);
 
+  lldb::UnwindPlanSP GetDebugFrameUnwindPlan(Target &target,
+                                             int current_offset);
+
+  lldb::UnwindPlanSP GetDebugFrameAugmentedUnwindPlan(Target &target,
+                                                      Thread &thread,
+                                                      int current_offset);
+
   lldb::UnwindPlanSP GetCompactUnwindUnwindPlan(Target &target,
                                                 int current_offset);
 
@@ -126,10 +133,12 @@ class FuncUnwinders {
 
   lldb::UnwindPlanSP m_unwind_plan_assembly_sp;
   lldb::UnwindPlanSP m_unwind_plan_eh_frame_sp;
-  lldb::UnwindPlanSP m_unwind_plan_eh_frame_augmented_sp; // augmented by
-                                                          // assembly inspection
-                                                          // so it's valid
-                                                          // everywhere
+  lldb::UnwindPlanSP m_unwind_plan_debug_frame_sp;
+
+  // augmented by assembly inspection so it's valid everywhere
+  lldb::UnwindPlanSP m_unwind_plan_eh_frame_augmented_sp;
+  lldb::UnwindPlanSP m_unwind_plan_debug_frame_augmented_sp;
+
   std::vector<lldb::UnwindPlanSP> m_unwind_plan_compact_unwind;
   lldb::UnwindPlanSP m_unwind_plan_arm_unwind_sp;
   lldb::UnwindPlanSP m_unwind_plan_fast_sp;
@@ -139,7 +148,9 @@ class FuncUnwinders {
   // Fetching the UnwindPlans can be expensive - if we've already attempted
   // to get one & failed, don't try again.
   bool m_tried_unwind_plan_assembly : 1, m_tried_unwind_plan_eh_frame : 1,
+      m_tried_unwind_plan_debug_frame : 1,
       m_tried_unwind_plan_eh_frame_augmented : 1,
+      m_tried_unwind_plan_debug_frame_augmented : 1,
       m_tried_unwind_plan_compact_unwind : 1,
       m_tried_unwind_plan_arm_unwind : 1, m_tried_unwind_fast : 1,
       m_tried_unwind_arch_default : 1,

lldb/include/lldb/Symbol/UnwindTable.h

@@ -27,6 +27,7 @@ class UnwindTable {
   ~UnwindTable();
 
   lldb_private::DWARFCallFrameInfo *GetEHFrameInfo();
+  lldb_private::DWARFCallFrameInfo *GetDebugFrameInfo();
 
   lldb_private::CompactUnwindInfo *GetCompactUnwindInfo();
 
@@ -58,6 +59,8 @@ class UnwindTable {
   void Dump(Stream &s);
 
   void Initialize();
+  llvm::Optional<AddressRange> GetAddressRange(const Address &addr,
+                                               SymbolContext &sc);
 
   typedef std::map<lldb::addr_t, lldb::FuncUnwindersSP> collection;
   typedef collection::iterator iterator;
@@ -70,6 +73,7 @@ class UnwindTable {
   std::mutex m_mutex;
 
   std::unique_ptr<DWARFCallFrameInfo> m_eh_frame_up;
+  std::unique_ptr<DWARFCallFrameInfo> m_debug_frame_up;
   std::unique_ptr<CompactUnwindInfo> m_compact_unwind_up;
   std::unique_ptr<ArmUnwindInfo> m_arm_unwind_up;
 

lldb/source/Commands/CommandObjectTarget.cpp

@@ -3426,6 +3426,23 @@ class CommandObjectTargetModulesShowUnwind : public CommandObjectParsed {
         result.GetOutputStream().Printf("\n");
       }
 
+      if (UnwindPlanSP plan_sp =
+              func_unwinders_sp->GetDebugFrameUnwindPlan(*target, 0)) {
+        result.GetOutputStream().Printf("debug_frame UnwindPlan:\n");
+        plan_sp->Dump(result.GetOutputStream(), thread.get(),
+                      LLDB_INVALID_ADDRESS);
+        result.GetOutputStream().Printf("\n");
+      }
+
+      if (UnwindPlanSP plan_sp =
+              func_unwinders_sp->GetDebugFrameAugmentedUnwindPlan(*target,
+                                                                  *thread, 0)) {
+        result.GetOutputStream().Printf("debug_frame augmented UnwindPlan:\n");
+        plan_sp->Dump(result.GetOutputStream(), thread.get(),
+                      LLDB_INVALID_ADDRESS);
+        result.GetOutputStream().Printf("\n");
+      }
+
       UnwindPlanSP arm_unwind_sp =
           func_unwinders_sp->GetArmUnwindUnwindPlan(*target, 0);
       if (arm_unwind_sp) {

lldb/source/Symbol/DWARFCallFrameInfo.cpp

@@ -161,8 +161,6 @@ DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile &objfile,
       m_fde_index(), m_fde_index_initialized(false),
       m_is_eh_frame(is_eh_frame) {}
 
-DWARFCallFrameInfo::~DWARFCallFrameInfo() {}
-
 bool DWARFCallFrameInfo::GetUnwindPlan(Address addr, UnwindPlan &unwind_plan) {
   FDEEntryMap::Entry fde_entry;
 
@@ -276,6 +274,12 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
     //    cie.cieID = cieID;
     cie_sp->ptr_encoding = DW_EH_PE_absptr; // default
     cie_sp->version = m_cfi_data.GetU8(&offset);
+    if (cie_sp->version > CFI_VERSION4) {
+      Host::SystemLog(Host::eSystemLogError,
+                      "CIE parse error: CFI version %d is not supported\n",
+                      cie_sp->version);
+      return nullptr;
+    }
 
     for (i = 0; i < CFI_AUG_MAX_SIZE; ++i) {
       cie_sp->augmentation[i] = m_cfi_data.GetU8(&offset);
@@ -294,11 +298,23 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
                       "CIE parse error: CIE augmentation string was too large "
                       "for the fixed sized buffer of %d bytes.\n",
                       CFI_AUG_MAX_SIZE);
-      return cie_sp;
+      return nullptr;
+    }
+
+    // m_cfi_data uses address size from target architecture of the process
+    // may ignore these fields?
+    if (!m_is_eh_frame && cie_sp->version >= CFI_VERSION4) {
+      cie_sp->address_size = m_cfi_data.GetU8(&offset);
+      cie_sp->segment_size = m_cfi_data.GetU8(&offset);
     }
+
     cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(&offset);
     cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(&offset);
-    cie_sp->return_addr_reg_num = m_cfi_data.GetU8(&offset);
+
+    cie_sp->return_addr_reg_num =
+        !m_is_eh_frame && cie_sp->version >= CFI_VERSION3
+            ? static_cast<uint32_t>(m_cfi_data.GetULEB128(&offset))
+            : m_cfi_data.GetU8(&offset);
 
     if (cie_sp->augmentation[0]) {
       // Get the length of the eh_frame augmentation data
@@ -461,24 +477,40 @@ void DWARFCallFrameInfo::GetFDEIndex() {
       m_fde_index_initialized = true;
       return;
     }
+
+    // An FDE entry contains CIE_pointer in debug_frame in same place as cie_id
+    // in eh_frame. CIE_pointer is an offset into the .debug_frame section.
+    // So, variable cie_offset should be equal to cie_id for debug_frame.
+    // FDE entries with cie_id == 0 shouldn't be ignored for it.
+    if ((cie_id == 0 && m_is_eh_frame) || cie_id == UINT32_MAX || len == 0) {
+      auto cie_sp = ParseCIE(current_entry);
+      if (!cie_sp) {
+        // Cannot parse, the reason is already logged
+        m_fde_index.Clear();
+        m_fde_index_initialized = true;
+        return;
+      }
+
+      m_cie_map[current_entry] = std::move(cie_sp);
+      offset = next_entry;
+      continue;
+    }
+
+    if (!m_is_eh_frame)
+      cie_offset = cie_id;
+
     if (cie_offset > m_cfi_data.GetByteSize()) {
-      Host::SystemLog(
-          Host::eSystemLogError,
-          "error: Invalid cie offset of 0x%x found in cie/fde at 0x%x\n",
-          cie_offset, current_entry);
+      Host::SystemLog(Host::eSystemLogError,
+                      "error: Invalid cie offset of 0x%x "
+                      "found in cie/fde at 0x%x\n",
+                      cie_offset, current_entry);
       // Don't trust anything in this eh_frame section if we find blatantly
       // invalid data.
       m_fde_index.Clear();
       m_fde_index_initialized = true;
       return;
     }
 
-    if (cie_id == 0 || cie_id == UINT32_MAX || len == 0) {
-      m_cie_map[current_entry] = ParseCIE(current_entry);
-      offset = next_entry;
-      continue;
-    }
-
     const CIE *cie = GetCIE(cie_offset);
     if (cie) {
       const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
@@ -531,7 +563,8 @@ bool DWARFCallFrameInfo::FDEToUnwindPlan(dw_offset_t dwarf_offset,
     cie_offset = m_cfi_data.GetU32(&offset);
   }
 
-  assert(cie_offset != 0 && cie_offset != UINT32_MAX);
+  // FDE entries with zeroth cie_offset may occur for debug_frame.
+  assert(!(m_is_eh_frame && 0 == cie_offset) && cie_offset != UINT32_MAX);
 
   // Translate the CIE_id from the eh_frame format, which
   // is relative to the FDE offset, into a __eh_frame section