Adjust DT_MIPS_RLD_MAP2 value

  DT_MIPS_RLD_MAP2 stores the difference between dynamic
  entry address and the address of the _r_debug (used by GDB)
  since the dynamic section and target address are on the
  different sides of the hole it needs to be adjusted accordingly

Bug: http://b/20658994
Bug: http://b/18051137
Change-Id: I4c5e379e8a4c68f029467df6dc660f81a7013a09
(cherry picked from commit 18c935ceabb54a32aff42f99c6d20680ac333157)

2 files changed, 14 insertions, 0 deletions

diff --git a/tools/relocation_packer/src/elf_file.cc b/tools/relocation_packer/src/elf_file.cc
index 6ac9deb..d06bd63 100644
--- a/tools/relocation_packer/src/elf_file.cc
+++ b/tools/relocation_packer/src/elf_file.cc
@@ -472,6 +472,16 @@ void ElfFile<ELF>::AdjustDynamicSectionForHole(Elf_Scn* dynamic_section,
               << " d_val adjusted to " << dynamic->d_un.d_val;
     }
 
+    // Special case: DT_MIPS_RLD_MAP2 stores the difference between dynamic
+    // entry address and the address of the _r_debug (used by GDB)
+    // since the dynamic section and target address are on the
+    // different sides of the hole it needs to be adjusted accordingly
+    if (tag == DT_MIPS_RLD_MAP2) {
+      dynamic->d_un.d_val += hole_size;
+      VLOG(1) << "dynamic[" << i << "] " << dynamic->d_tag
+              << " d_val adjusted to " << dynamic->d_un.d_val;
+    }
+
     // Ignore DT_RELCOUNT and DT_RELACOUNT: (1) nobody uses them and
     // technically (2) the relative relocation count is not changed.
 
diff --git a/tools/relocation_packer/src/elf_traits.h b/tools/relocation_packer/src/elf_traits.h
index 41b06c8..1c938fa 100644
--- a/tools/relocation_packer/src/elf_traits.h
+++ b/tools/relocation_packer/src/elf_traits.h
@@ -10,6 +10,10 @@
 #include "elf.h"
 #include "libelf.h"
 
+#if !defined(DT_MIPS_RLD_MAP2)
+#define DT_MIPS_RLD_MAP2 0x70000035
+#endif
+
 // ELF is a traits structure used to provide convenient aliases for
 // 32/64 bit Elf types and functions, depending on the target file.