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Commit 239425b9 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Fix bug when doing signal handler lookup. 

The new lld linker uses all non-zero offset executable maps. There was
a bug when trying to find if the stack is in a signal handler that caused
the code to read the wrong place in the elf. Fixed by not adding the elf
offset to the relative pc.

Also fixed the unwind_for_offline tool to dump multiple stacks if necessary.

Added new offline unit test that would have failed with the old code.

Bug: 79936827

Test: Ran unit tests and libbacktrace unit tests.
Test: Dumped backtraces of system pids.
Test: Ran 137-cfi art test.
Change-Id: Iaca8c18c2a314902e64c3f72831234297e8dcb1b
parent 3464bc4b

libunwindstack/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -202,6 +202,7 @@ cc_test { 
        "tests/files/offline/jit_debug_x86/*",

        "tests/files/offline/jit_map_arm/*",

        "tests/files/offline/gnu_debugdata_arm/*",

        "tests/files/offline/offset_arm/*",

        "tests/files/offline/straddle_arm/*",

        "tests/files/offline/straddle_arm64/*",

    ],

libunwindstack/Elf.cpp

+3 −3
Original line number Diff line number Diff line
@@ -160,14 +160,14 @@ uint64_t Elf::GetLastErrorAddress() { 
}



// The relative pc is always relative to the start of the map from which it comes.

bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, uint64_t elf_offset, Regs* regs,

               Memory* process_memory, bool* finished) {

bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,

               bool* finished) {

  if (!valid_) {

    return false;

  }



  // The relative pc expectd by StepIfSignalHandler is relative to the start of the elf.

  if (regs->StepIfSignalHandler(rel_pc + elf_offset, this, process_memory)) {

  if (regs->StepIfSignalHandler(rel_pc, this, process_memory)) {

    *finished = false;

    return true;

  }

libunwindstack/Unwinder.cpp

+1 −2
Original line number Diff line number Diff line
@@ -220,8 +220,7 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip, 
          in_device_map = true;

        } else {

          bool finished;

          stepped = elf->Step(rel_pc, step_pc, map_info->elf_offset, regs_, process_memory_.get(),

                              &finished);

          stepped = elf->Step(rel_pc, step_pc, regs_, process_memory_.get(), &finished);

          elf->GetLastError(&last_error_);

          if (stepped && finished) {

            break;

libunwindstack/include/unwindstack/Elf.h

+2 −2
Original line number Diff line number Diff line
@@ -65,8 +65,8 @@ class Elf { 


  uint64_t GetRelPc(uint64_t pc, const MapInfo* map_info);



  bool Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, uint64_t elf_offset, Regs* regs,

            Memory* process_memory, bool* finished);

  bool Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,

            bool* finished);



  ElfInterface* CreateInterfaceFromMemory(Memory* memory);

libunwindstack/tests/ElfTest.cpp

+4 −4
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ TEST_F(ElfTest, elf_invalid) { 
  ASSERT_FALSE(elf.GetFunctionName(0, &name, &func_offset));



  bool finished;

  ASSERT_FALSE(elf.Step(0, 0, 0, nullptr, nullptr, &finished));

  ASSERT_FALSE(elf.Step(0, 0, nullptr, nullptr, &finished));

}



TEST_F(ElfTest, elf32_invalid_machine) {
@@ -330,7 +330,7 @@ TEST_F(ElfTest, step_in_signal_map) { 
  elf.FakeSetValid(true);

  elf.FakeSetLoadBias(0);

  bool finished;

  ASSERT_TRUE(elf.Step(0x1000, 0x1000, 0x2000, &regs, &process_memory, &finished));

  ASSERT_TRUE(elf.Step(0x3000, 0x1000, &regs, &process_memory, &finished));

  EXPECT_FALSE(finished);

  EXPECT_EQ(15U, regs.pc());

  EXPECT_EQ(13U, regs.sp());
@@ -370,7 +370,7 @@ TEST_F(ElfTest, step_in_interface) { 
  EXPECT_CALL(*interface, Step(0x1000, 0, &regs, &process_memory, &finished))

      .WillOnce(::testing::Return(true));



  ASSERT_TRUE(elf.Step(0x1004, 0x1000, 0x2000, &regs, &process_memory, &finished));

  ASSERT_TRUE(elf.Step(0x1004, 0x1000, &regs, &process_memory, &finished));

}



TEST_F(ElfTest, step_in_interface_non_zero_load_bias) {
@@ -388,7 +388,7 @@ TEST_F(ElfTest, step_in_interface_non_zero_load_bias) { 
  EXPECT_CALL(*interface, Step(0x7300, 0x4000, &regs, &process_memory, &finished))

      .WillOnce(::testing::Return(true));



  ASSERT_TRUE(elf.Step(0x7304, 0x7300, 0x2000, &regs, &process_memory, &finished));

  ASSERT_TRUE(elf.Step(0x7304, 0x7300, &regs, &process_memory, &finished));

}



TEST_F(ElfTest, get_global_invalid_elf) {