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Commit e4df5f5a authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Fix computation of pc. 

Fix the case where a non-zero load bias or a non-zero elf offset causes
the pc to be set incorrectly.

Add unit tests for these cases.

Bug: 73172903

Test: Ran unit tests.
Test: Ran the unit tests from the simpleperf CL that detected the failure.
Change-Id: Id8802c00b34c66875edd4926a20c5fccd2bb7d72
parent 73a2508d

libunwindstack/Unwinder.cpp

+1 −1
Original line number Diff line number Diff line
@@ -91,7 +91,7 @@ void Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t adjusted_rel_pc 
    return;

  }



  frame->pc = map_info->start + adjusted_rel_pc;

  frame->pc = map_info->start + adjusted_rel_pc - elf->GetLoadBias() - map_info->elf_offset;

  frame->map_name = map_info->name;

  frame->map_offset = map_info->offset;

  frame->map_start = map_info->start;

libunwindstack/tests/UnwinderTest.cpp

+72 −0
Original line number Diff line number Diff line
@@ -102,6 +102,22 @@ class UnwinderTest : public ::testing::Test { 
    info->load_bias = 0;

    maps_.FakeAddMapInfo(info);



    info = new MapInfo(0xa5000, 0xa6000, 0, PROT_READ | PROT_WRITE | PROT_EXEC,

                       "/fake/fake_load_bias.so");

    elf = new ElfFake(new MemoryFake);

    info->elf.reset(elf);

    elf->FakeSetInterface(new ElfInterfaceFake(nullptr));

    elf->FakeSetLoadBias(0x5000);

    maps_.FakeAddMapInfo(info);



    info = new MapInfo(0xa7000, 0xa8000, 0, PROT_READ | PROT_WRITE | PROT_EXEC,

                       "/fake/fake_offset.oat");

    elf = new ElfFake(new MemoryFake);

    info->elf.reset(elf);

    elf->FakeSetInterface(new ElfInterfaceFake(nullptr));

    info->elf_offset = 0x8000;

    maps_.FakeAddMapInfo(info);



    process_memory_.reset(new MemoryFake);

  }
@@ -180,6 +196,62 @@ TEST_F(UnwinderTest, multiple_frames) { 
  EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);

}



TEST_F(UnwinderTest, non_zero_load_bias) {

  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));



  regs_.FakeSetPc(0xa5500);

  regs_.FakeSetSp(0x10000);

  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));



  Unwinder unwinder(64, &maps_, &regs_, process_memory_);

  unwinder.Unwind();

  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());



  ASSERT_EQ(1U, unwinder.NumFrames());



  auto* frame = &unwinder.frames()[0];

  EXPECT_EQ(0U, frame->num);

  EXPECT_EQ(0x5500U, frame->rel_pc);

  EXPECT_EQ(0xa5500U, frame->pc);

  EXPECT_EQ(0x10000U, frame->sp);

  EXPECT_EQ("Frame0", frame->function_name);

  EXPECT_EQ(0U, frame->function_offset);

  EXPECT_EQ("/fake/fake_load_bias.so", frame->map_name);

  EXPECT_EQ(0U, frame->map_offset);

  EXPECT_EQ(0xa5000U, frame->map_start);

  EXPECT_EQ(0xa6000U, frame->map_end);

  EXPECT_EQ(0x5000U, frame->map_load_bias);

  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);

}



TEST_F(UnwinderTest, non_zero_elf_offset) {

  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));



  regs_.FakeSetPc(0xa7500);

  regs_.FakeSetSp(0x10000);

  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));



  Unwinder unwinder(64, &maps_, &regs_, process_memory_);

  unwinder.Unwind();

  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());



  ASSERT_EQ(1U, unwinder.NumFrames());



  auto* frame = &unwinder.frames()[0];

  EXPECT_EQ(0U, frame->num);

  EXPECT_EQ(0x8500U, frame->rel_pc);

  EXPECT_EQ(0xa7500U, frame->pc);

  EXPECT_EQ(0x10000U, frame->sp);

  EXPECT_EQ("Frame0", frame->function_name);

  EXPECT_EQ(0U, frame->function_offset);

  EXPECT_EQ("/fake/fake_offset.oat", frame->map_name);

  EXPECT_EQ(0U, frame->map_offset);

  EXPECT_EQ(0xa7000U, frame->map_start);

  EXPECT_EQ(0xa8000U, frame->map_end);

  EXPECT_EQ(0U, frame->map_load_bias);

  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);

}



TEST_F(UnwinderTest, non_zero_map_offset) {

  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));