commit d2d1504805f9bf2a9925dd4f09bfe5329f819030
author Saleem Abdulrasool <compnerd@compnerd.org> Sat Apr 23 16:00:15 2016 +0000
committer Saleem Abdulrasool <compnerd@compnerd.org> Sat Apr 23 16:00:15 2016 +0000
tree bd1c584fc825171c4b0fffcf2760975f005e7900
parent 66b0a87ae8d6e148e089e7cd6d45d50887e0ea63

ObjectFile: parse EABI Attributes

This adds basic parsing of the EABI attributes section.  This section contains
additional information about the target for which the file was built.  Attempt
to infer additional architecture information from that section.

llvm-svn: 267291

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index bb388d4..7641684 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -31,6 +31,7 @@
 
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/ARMBuildAttributes.h"
 #include "llvm/Support/MathExtras.h"
 
 #define CASE_AND_STREAM(s, def, width)                  \
@@ -1516,6 +1517,93 @@
     return error;
 }
 
+void
+ObjectFileELF::ParseARMAttributes(DataExtractor &data, uint64_t length, ArchSpec &arch_spec)
+{
+    lldb::offset_t Offset = 0;
+
+    uint8_t FormatVersion = data.GetU8(&Offset);
+    if (FormatVersion != llvm::ARMBuildAttrs::Format_Version)
+      return;
+
+    Offset = Offset + sizeof(uint32_t); // Section Length
+    llvm::StringRef VendorName = data.GetCStr(&Offset);
+
+    if (VendorName != "aeabi")
+      return;
+
+    if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment)
+        arch_spec.GetTriple().setEnvironment(llvm::Triple::EABI);
+
+    while (Offset < length)
+    {
+        uint8_t Tag = data.GetU8(&Offset);
+        uint32_t Size = data.GetU32(&Offset);
+
+        if (Tag != llvm::ARMBuildAttrs::File || Size == 0)
+            continue;
+
+        while (Offset < length)
+        {
+            uint64_t Tag = data.GetULEB128(&Offset);
+            switch (Tag)
+            {
+                default:
+                    if (Tag < 32)
+                        data.GetULEB128(&Offset);
+                    else if (Tag % 2 == 0)
+                        data.GetULEB128(&Offset);
+                    else
+                        data.GetCStr(&Offset);
+
+                    break;
+
+                case llvm::ARMBuildAttrs::CPU_raw_name:
+                case llvm::ARMBuildAttrs::CPU_name:
+                    data.GetCStr(&Offset);
+
+                    break;
+
+                case llvm::ARMBuildAttrs::THUMB_ISA_use:
+                {
+                    uint64_t ThumbISA = data.GetULEB128(&Offset);
+
+                    // NOTE: ignore ThumbISA == llvm::ARMBuildAttrs::AllowThumbDerived
+                    // since that derives it based on the architecutre/profile
+                    if (ThumbISA == llvm::ARMBuildAttrs::AllowThumb32)
+                        if (arch_spec.GetTriple().getArch() == llvm::Triple::UnknownArch ||
+                            arch_spec.GetTriple().getArch() == llvm::Triple::arm)
+                            arch_spec.GetTriple().setArch(llvm::Triple::thumb);
+
+                    break;
+                }
+                case llvm::ARMBuildAttrs::ABI_VFP_args:
+                {
+                    uint64_t VFPArgs = data.GetULEB128(&Offset);
+
+                    if (VFPArgs == llvm::ARMBuildAttrs::BaseAAPCS)
+                    {
+                        if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment ||
+                            arch_spec.GetTriple().getEnvironment() == llvm::Triple::EABIHF)
+                            arch_spec.GetTriple().setEnvironment(llvm::Triple::EABI);
+
+                        arch_spec.SetFlags(ArchSpec::eARM_abi_soft_float);
+                    }
+                    else if (VFPArgs == llvm::ARMBuildAttrs::HardFPAAPCS)
+                    {
+                        if (arch_spec.GetTriple().getEnvironment() == llvm::Triple::UnknownEnvironment ||
+                            arch_spec.GetTriple().getEnvironment() == llvm::Triple::EABI)
+                            arch_spec.GetTriple().setEnvironment(llvm::Triple::EABIHF);
+
+                        arch_spec.SetFlags(ArchSpec::eARM_abi_hard_float);
+                    }
+
+                    break;
+                }
+            }
+        }
+    }
+}
 
 //----------------------------------------------------------------------
 // GetSectionHeaderInfo
@@ -1648,6 +1736,18 @@
                     arch_spec.SetFlags (arch_flags);
                 }
 
+                if (arch_spec.GetMachine() == llvm::Triple::arm || arch_spec.GetMachine() == llvm::Triple::thumb)
+                {
+                    DataExtractor data;
+
+                    if (sheader.sh_type != SHT_ARM_ATTRIBUTES)
+                        continue;
+                    if (section_size == 0 || set_data(data, sheader.sh_offset, section_size) != section_size)
+                        continue;
+
+                    ParseARMAttributes(data, section_size, arch_spec);
+                }
+
                 if (name == g_sect_name_gnu_debuglink)
                 {
                     DataExtractor data;

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h

diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h
index 0a1f78e..e2f73f5 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h
@@ -298,6 +298,10 @@
     size_t
     ParseSectionHeaders();
 
+    static void
+    ParseARMAttributes(lldb_private::DataExtractor &data, uint64_t length,
+                       lldb_private::ArchSpec &arch_spec);
+
     /// Parses the elf section headers and returns the uuid, debug link name, crc, archspec.
     static size_t
     GetSectionHeaderInfo(SectionHeaderColl &section_headers,