Add support for packed relocations.

Change-Id: I796a4ce86d3fccb8361c19889419c96147ee3c9f

linker/linker.cpp

@@ -53,6 +53,7 @@
 #include "linker_allocator.h"
 #include "linker_debug.h"
 #include "linker_environ.h"
+#include "linker_leb128.h"
 #include "linker_phdr.h"
 #include "linker_relocs.h"
 #include "linker_reloc_iterators.h"
@@ -1302,6 +1303,10 @@ template<typename ElfRelIteratorT>
 bool soinfo::relocate(ElfRelIteratorT&& rel_iterator, const soinfo_list_t& global_group, const soinfo_list_t& local_group) {
   for (size_t idx = 0; rel_iterator.has_next(); ++idx) {
     const auto rel = rel_iterator.next();
+    if (rel == nullptr) {
+      return false;
+    }
+
     ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
     ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
 
@@ -1407,16 +1412,16 @@ bool soinfo::relocate(ElfRelIteratorT&& rel_iterator, const soinfo_list_t& globa
         MARK(rel->r_offset);
         TRACE_TYPE(RELO, "RELO RELATIVE %16p <- %16p\n",
                    reinterpret_cast<void*>(reloc),
-                   reinterpret_cast<void*>(base + addend));
-        *reinterpret_cast<ElfW(Addr)*>(reloc) = (base + addend);
+                   reinterpret_cast<void*>(load_bias + addend));
+        *reinterpret_cast<ElfW(Addr)*>(reloc) = (load_bias + addend);
         break;
       case R_GENERIC_IRELATIVE:
         count_relocation(kRelocRelative);
         MARK(rel->r_offset);
         TRACE_TYPE(RELO, "RELO IRELATIVE %16p <- %16p\n",
                     reinterpret_cast<void*>(reloc),
-                    reinterpret_cast<void*>(base + addend));
-        *reinterpret_cast<ElfW(Addr)*>(reloc) = call_ifunc_resolver(base + addend);
+                    reinterpret_cast<void*>(load_bias + addend));
+        *reinterpret_cast<ElfW(Addr)*>(reloc) = call_ifunc_resolver(load_bias + addend);
         break;
 
 #if defined(__aarch64__)
@@ -2053,6 +2058,22 @@ bool soinfo::prelink_image() {
         rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
         break;
 
+      case DT_ANDROID_RELA:
+        android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
+        break;
+
+      case DT_ANDROID_RELASZ:
+        android_relocs_size_ = d->d_un.d_val;
+        break;
+
+      case DT_ANDROID_REL:
+        DL_ERR("unsupported DT_ANDROID_REL in \"%s\"", name);
+        return false;
+
+      case DT_ANDROID_RELSZ:
+        DL_ERR("unsupported DT_ANDROID_RELSZ in \"%s\"", name);
+        return false;
+
       case DT_RELAENT:
         if (d->d_un.d_val != sizeof(ElfW(Rela))) {
           DL_ERR("invalid DT_RELAENT: %zd", static_cast<size_t>(d->d_un.d_val));
@@ -2071,6 +2092,7 @@ bool soinfo::prelink_image() {
       case DT_RELSZ:
         DL_ERR("unsupported DT_RELSZ in \"%s\"", name);
         return false;
+
 #else
       case DT_REL:
         rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
@@ -2087,6 +2109,22 @@ bool soinfo::prelink_image() {
         }
         break;
 
+      case DT_ANDROID_REL:
+        android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
+        break;
+
+      case DT_ANDROID_RELSZ:
+        android_relocs_size_ = d->d_un.d_val;
+        break;
+
+      case DT_ANDROID_RELA:
+        DL_ERR("unsupported DT_ANDROID_RELA in \"%s\"", name);
+        return false;
+
+      case DT_ANDROID_RELASZ:
+        DL_ERR("unsupported DT_ANDROID_RELASZ in \"%s\"", name);
+        return false;
+
       // "Indicates that all RELATIVE relocations have been concatenated together,
       // and specifies the RELATIVE relocation count."
       //
@@ -2094,9 +2132,15 @@ bool soinfo::prelink_image() {
       // Not currently used by bionic linker - ignored.
       case DT_RELCOUNT:
         break;
+
       case DT_RELA:
         DL_ERR("unsupported DT_RELA in \"%s\"", name);
         return false;
+
+      case DT_RELASZ:
+        DL_ERR("unsupported DT_RELASZ in \"%s\"", name);
+        return false;
+
 #endif
       case DT_INIT:
         init_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
@@ -2251,7 +2295,8 @@ bool soinfo::prelink_image() {
   return true;
 }
 
-bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group, const android_dlextinfo* extinfo) {
+bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group,
+                        const android_dlextinfo* extinfo) {
 
   local_group_root_ = local_group.front();
   if (local_group_root_ == nullptr) {
@@ -2272,6 +2317,40 @@ bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t&
   }
 #endif
 
+  if (android_relocs_ != nullptr) {
+    // check signature
+    if (android_relocs_size_ > 3 &&
+        android_relocs_[0] == 'A' &&
+        android_relocs_[1] == 'P' &&
+        (android_relocs_[2] == 'U' || android_relocs_[2] == 'S') &&
+        android_relocs_[3] == '2') {
+      DEBUG("[ android relocating %s ]", name);
+
+      bool relocated = false;
+      const uint8_t* packed_relocs = android_relocs_ + 4;
+      const size_t packed_relocs_size = android_relocs_size_ - 4;
+
+      if (android_relocs_[2] == 'U') {
+        relocated = relocate(
+            packed_reloc_iterator<leb128_decoder>(
+              leb128_decoder(packed_relocs, packed_relocs_size)),
+            global_group, local_group);
+      } else { // android_relocs_[2] == 'S'
+        relocated = relocate(
+            packed_reloc_iterator<sleb128_decoder>(
+              sleb128_decoder(packed_relocs, packed_relocs_size)),
+            global_group, local_group);
+      }
+
+      if (!relocated) {
+        return false;
+      }
+    } else {
+      DL_ERR("bad android relocation header.");
+      return false;
+    }
+  }
+
 #if defined(USE_RELA)
   if (rela_ != nullptr) {
     DEBUG("[ relocating %s ]", name);