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Commit 0ca49b09 authored by Yabin Cui's avatar Yabin Cui
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libBacktraceOffline: try both .debug_frame and .ARM.exidx on arm. 

Currently, libBacktraceOffline doesn't try .ARM.exidx if a function
appears in .debug_frame. This make it can't unwind through functions
appear in both .debug_frame and .ARM.exidx, but having dwarf instructions
not accepted by libunwind.
This patch fixes this by trying first .debug_frame then .ARM.exidx on arm.

Bug: http://b/69383534
Test: run libbacktrace_test on arm.

Change-Id: Ib95dd56d5cc123a20948e880b51b28ddc04b4a6e
parent d65c6ba9

libbacktrace/BacktraceOffline.cpp

+3 −1
Original line number Diff line number Diff line
@@ -222,6 +222,7 @@ bool BacktraceOffline::Unwind(size_t num_ignore_frames, ucontext_t* context) { 
    } else {

      num_ignore_frames--;

    }

    is_debug_frame_used_ = false;

    ret = unw_step(&cursor);

  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
@@ -318,7 +319,8 @@ bool BacktraceOffline::FindProcInfo(unw_addr_space_t addr_space, uint64_t ip, 
      }

    }

  }

  if (debug_frame->has_debug_frame || debug_frame->has_gnu_debugdata) {

  if (!is_debug_frame_used_ && (debug_frame->has_debug_frame || debug_frame->has_gnu_debugdata)) {

    is_debug_frame_used_ = true;

    unw_dyn_info_t di;

    unw_word_t segbase = map.start - debug_frame->min_vaddr;

    // TODO: http://b/32916571

libbacktrace/BacktraceOffline.h

+10 −1
Original line number Diff line number Diff line
@@ -48,7 +48,8 @@ class BacktraceOffline : public Backtrace { 
                   bool cache_file)

      : Backtrace(pid, tid, map),

        cache_file_(cache_file),

        context_(nullptr) {

        context_(nullptr),

        is_debug_frame_used_(false) {

    stack_space_.start = stack.start;

    stack_space_.end = stack.end;

    stack_space_.data = stack.data;
@@ -78,6 +79,14 @@ class BacktraceOffline : public Backtrace { 
  Space arm_extab_space_;

  Space arm_exidx_space_;

  Space stack_space_;



  // is_debug_frame_used_ is to make sure we can try both .debug_frame and .ARM.exidx in

  // FindProcInfo() on ARM. One example is EsxContext::Clear() in

  // vendor/lib/egl/libGLESv2_adreno.so. EsxContext::Clear() appears in both .debug_frame and

  // .ARM.exidx. However, libunwind fails to execute debug_frame instruction

  // "DW_CFA_offset_extended: r265 at cfa-48". So we need to try .ARM.exidx to unwind that

  // function.

  bool is_debug_frame_used_;

};



#endif  // _LIBBACKTRACE_BACKTRACE_OFFLINE_H

libbacktrace/backtrace_offline_test.cpp

+19 −49
Original line number Diff line number Diff line
@@ -357,26 +357,24 @@ TEST(libbacktrace, offline_arm_exidx) { 
  BacktraceOfflineTest("arm", "libbacktrace_test_arm_exidx.so");

}



// This test tests the situation that ranges of functions covered by .eh_frame and .ARM.exidx

// overlap with each other, which appears in /system/lib/libart.so.

TEST(libbacktrace, offline_unwind_mix_eh_frame_and_arm_exidx) {

  // TODO: For now, only run on the given arch.

  if (std::string(ABI_STRING) != "arm") {

static void LibUnwindingTest(const std::string& arch, const std::string& testdata_name,

                             const std::string& testlib_name) {

  if (std::string(ABI_STRING) != arch) {

    GTEST_LOG_(INFO) << "Skipping test since offline for arm on " << ABI_STRING

                     << " isn't supported.";

    return;

  }

  const std::string testlib_path(GetTestPath("libart.so"));

  const std::string testlib_path(GetTestPath(testlib_name));

  struct stat st;

  ASSERT_EQ(0, stat(testlib_path.c_str(), &st)) << "can't find testlib " << testlib_path;



  const std::string offline_testdata_path(GetTestPath("offline_testdata_for_libart"));

  const std::string offline_testdata_path(GetTestPath(testdata_name));

  OfflineTestData testdata;

  ASSERT_TRUE(ReadOfflineTestData(offline_testdata_path, &testdata));



  // Fix path of /system/lib/libart.so.

  // Fix path of the testlib.

  for (auto& map : testdata.maps) {

    if (map.name.find("libart.so") != std::string::npos) {

    if (map.name.find(testlib_name) != std::string::npos) {

      map.name = testlib_path;

    }

  }
@@ -392,9 +390,8 @@ TEST(libbacktrace, offline_unwind_mix_eh_frame_and_arm_exidx) { 
  ucontext_t ucontext = GetUContextFromUnwContext(testdata.unw_context);

  ASSERT_TRUE(backtrace->Unwind(0, &ucontext));



  // The last frame is outside of libart.so

  ASSERT_EQ(testdata.symbols.size() + 1, backtrace->NumFrames());

  for (size_t i = 0; i + 1 < backtrace->NumFrames(); ++i) {

  ASSERT_EQ(testdata.symbols.size(), backtrace->NumFrames());

  for (size_t i = 0; i < backtrace->NumFrames(); ++i) {

    uintptr_t vaddr_in_file =

        backtrace->GetFrame(i)->pc - testdata.maps[0].start + testdata.maps[0].load_bias;

    std::string name = FunctionNameForAddress(vaddr_in_file, testdata.symbols);
@@ -402,43 +399,16 @@ TEST(libbacktrace, offline_unwind_mix_eh_frame_and_arm_exidx) { 
  }

}



TEST(libbacktrace, offline_debug_frame_with_load_bias) {

  if (std::string(ABI_STRING) != "arm") {

    GTEST_LOG_(INFO) << "Skipping test since offline for arm on " << ABI_STRING

                     << " isn't supported.";

    return;

// This test tests the situation that ranges of functions covered by .eh_frame and .ARM.exidx

// overlap with each other, which appears in /system/lib/libart.so.

TEST(libbacktrace, offline_unwind_mix_eh_frame_and_arm_exidx) {

  LibUnwindingTest("arm", "offline_testdata_for_libart", "libart.so");

}

  const std::string testlib_path(GetTestPath("libandroid_runtime.so"));

  struct stat st;

  ASSERT_EQ(0, stat(testlib_path.c_str(), &st)) << "can't find testlib " << testlib_path;



  const std::string offline_testdata_path(GetTestPath("offline_testdata_for_libandroid_runtime"));

  OfflineTestData testdata;

  ASSERT_TRUE(ReadOfflineTestData(offline_testdata_path, &testdata));



  // Fix path of /system/lib/libandroid_runtime.so.

  for (auto& map : testdata.maps) {

    if (map.name.find("libandroid_runtime.so") != std::string::npos) {

      map.name = testlib_path;

    }

TEST(libbacktrace, offline_debug_frame_with_load_bias) {

  LibUnwindingTest("arm", "offline_testdata_for_libandroid_runtime", "libandroid_runtime.so");

}



  // Do offline backtrace.

  std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(testdata.pid, testdata.maps));

  ASSERT_TRUE(map != nullptr);



  std::unique_ptr<Backtrace> backtrace(

      Backtrace::CreateOffline(testdata.pid, testdata.tid, map.get(), testdata.stack_info));

  ASSERT_TRUE(backtrace != nullptr);



  ucontext_t ucontext = GetUContextFromUnwContext(testdata.unw_context);

  ASSERT_TRUE(backtrace->Unwind(0, &ucontext));



  ASSERT_EQ(testdata.symbols.size(), backtrace->NumFrames());

  for (size_t i = 0; i < backtrace->NumFrames(); ++i) {

    uintptr_t vaddr_in_file =

        backtrace->GetFrame(i)->pc - testdata.maps[0].start + testdata.maps[0].load_bias;

    std::string name = FunctionNameForAddress(vaddr_in_file, testdata.symbols);

    ASSERT_EQ(name, testdata.symbols[i].name);

  }

TEST(libbacktrace, offline_try_armexidx_after_debug_frame) {

  LibUnwindingTest("arm", "offline_testdata_for_libGLESv2_adreno", "libGLESv2_adreno.so");

}

libbacktrace/testdata/arm/libGLESv2_adreno.so

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libbacktrace/testdata/arm/offline_testdata_for_libGLESv2_adreno

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+6 −0
Original line number Diff line number Diff line 
pid: 7288 tid: 31656

regs: pc: cc416235 sp: cc17f000

map: start: cc361000 end: cc758000 offset: 0 load_bias: 9000 flags: 5 name: /vendor/lib/egl/libGLESv2_adreno.so

stack: start: cc17f254 end: cc17f258 size: 4 b36141cc

function: start: be1f0 end: be304 name: EsxContext::Clear(unsigned int, unsigned int, unsigned int, EsxClearValues*)

function: start: be058 end: be1f0 name: EsxContext::ClearBuffersForDebug()