commit fbca3000972176114eca6e1434e631a5a99622de
author Yong Li <yongl0722@gmail.com> Thu Apr 23 20:40:29 2020 +0000
committer Yong Li <yongl0722@gmail.com> Mon Apr 27 21:07:50 2020 +0000
tree 9dd0a7c589329c430084c5f214c7d8e909fb9067
parent 451197cb640c63320a4ed619a9d3e5aa99b80057

Fix GetGlobalVariableOffset with tagged pointer in aarch64

Tagged pointer for aarch64 since Android R would lead top byte to have
random values. For example of a symbol from libart.so in a hwasan
enabled device in Android R:

1490: 8800000000b094a0   144 OBJECT  GLOBAL 24 __dex_debug_descriptor

We need to mask off the top byte so that the address range comparison
would work as intended.

Test: Ran new unit test

Signed-off-by: Yong Li <yongl0722@gmail.com>
Change-Id: Ia8c638e16baff57740c569e9eaf9cfd1f5bd3fad

libunwindstack/Elf.cpp

diff --git a/libunwindstack/Elf.cpp b/libunwindstack/Elf.cpp
index f01b092..286febc 100644
--- a/libunwindstack/Elf.cpp
+++ b/libunwindstack/Elf.cpp
@@ -124,6 +124,12 @@
     return false;
   }
 
+  if (arch() == ARCH_ARM64) {
+    // Tagged pointer after Android R would lead top byte to have random values
+    // https://source.android.com/devices/tech/debug/tagged-pointers
+    vaddr &= (1ULL << 56) - 1;
+  }
+
   // Check the .data section.
   uint64_t vaddr_start = interface_->data_vaddr_start();
   if (vaddr >= vaddr_start && vaddr < interface_->data_vaddr_end()) {

libunwindstack/tests/ElfFake.h

diff --git a/libunwindstack/tests/ElfFake.h b/libunwindstack/tests/ElfFake.h
index fc90dab..3b6cb80 100644
--- a/libunwindstack/tests/ElfFake.h
+++ b/libunwindstack/tests/ElfFake.h
@@ -55,6 +55,8 @@
 
   void FakeSetLoadBias(uint64_t load_bias) { load_bias_ = load_bias; }
 
+  void FakeSetArch(ArchEnum arch) { arch_ = arch; }
+
   void FakeSetInterface(ElfInterface* interface) { interface_.reset(interface); }
   void FakeSetGnuDebugdataInterface(ElfInterface* interface) {
     gnu_debugdata_interface_.reset(interface);

libunwindstack/tests/ElfTest.cpp

diff --git a/libunwindstack/tests/ElfTest.cpp b/libunwindstack/tests/ElfTest.cpp
index 1f3ed81..f0852a4 100644
--- a/libunwindstack/tests/ElfTest.cpp
+++ b/libunwindstack/tests/ElfTest.cpp
@@ -438,6 +438,48 @@
   EXPECT_EQ(0xc080U, offset);
 }
 
+TEST_F(ElfTest, get_global_vaddr_with_tagged_pointer) {
+  ElfFake elf(memory_);
+  elf.FakeSetValid(true);
+  elf.FakeSetArch(ARCH_ARM64);
+
+  ElfInterfaceMock* interface = new ElfInterfaceMock(memory_);
+  elf.FakeSetInterface(interface);
+  interface->MockSetDataVaddrStart(0x500);
+  interface->MockSetDataVaddrEnd(0x600);
+  interface->MockSetDataOffset(0xa000);
+
+  std::string global("something");
+  EXPECT_CALL(*interface, GetGlobalVariable(global, ::testing::_))
+      .WillOnce(::testing::DoAll(::testing::SetArgPointee<1>(0x8800000000000580),
+                                 ::testing::Return(true)));
+
+  uint64_t offset;
+  ASSERT_TRUE(elf.GetGlobalVariableOffset(global, &offset));
+  EXPECT_EQ(0xa080U, offset);
+}
+
+TEST_F(ElfTest, get_global_vaddr_without_tagged_pointer) {
+  ElfFake elf(memory_);
+  elf.FakeSetValid(true);
+  elf.FakeSetArch(ARCH_X86_64);
+
+  ElfInterfaceMock* interface = new ElfInterfaceMock(memory_);
+  elf.FakeSetInterface(interface);
+  interface->MockSetDataVaddrStart(0x8800000000000500);
+  interface->MockSetDataVaddrEnd(0x8800000000000600);
+  interface->MockSetDataOffset(0x880000000000a000);
+
+  std::string global("something");
+  EXPECT_CALL(*interface, GetGlobalVariable(global, ::testing::_))
+      .WillOnce(::testing::DoAll(::testing::SetArgPointee<1>(0x8800000000000580),
+                                 ::testing::Return(true)));
+
+  uint64_t offset;
+  ASSERT_TRUE(elf.GetGlobalVariableOffset(global, &offset));
+  EXPECT_EQ(0x880000000000a080U, offset);
+}
+
 TEST_F(ElfTest, is_valid_pc_elf_invalid) {
   ElfFake elf(memory_);
   elf.FakeSetValid(false);