1#include <libunwind.h>
2#include <pthread.h>
3#include <stdint.h>
4#include <string.h>
5
6#include <functional>
7#include <memory>
8#include <string>
9#include <utility>
10#include <vector>
11
12#include <backtrace/Backtrace.h>
13#include <backtrace/BacktraceMap.h>
14#include <cutils/threads.h>
15
16#include <gtest/gtest.h>
17
18extern "C" {
19// Prototypes for functions in the test library.
20int test_level_one(int, int, int, int, void (*)(void*), void*);
21int test_level_two(int, int, int, int, void (*)(void*), void*);
22int test_level_three(int, int, int, int, void (*)(void*), void*);
23int test_level_four(int, int, int, int, void (*)(void*), void*);
24int test_recursive_call(int, void (*)(void*), void*);
25}
26
27static volatile bool g_exit_flag = false;
28
29static void GetContextAndExit(void* arg) {
30  unw_context_t* unw_context = reinterpret_cast<unw_context_t*>(arg);
31  unw_getcontext(unw_context);
32  // Don't touch the stack anymore.
33  while (!g_exit_flag) {
34  }
35}
36
37struct OfflineThreadArg {
38  unw_context_t unw_context;
39  pid_t tid;
40  std::function<int(void (*)(void*), void*)> function;
41};
42
43static void* OfflineThreadFunc(void* arg) {
44  OfflineThreadArg* fn_arg = reinterpret_cast<OfflineThreadArg*>(arg);
45  fn_arg->tid = gettid();
46  fn_arg->function(GetContextAndExit, &fn_arg->unw_context);
47  return nullptr;
48}
49
50static ucontext_t GetUContextFromUnwContext(const unw_context_t& unw_context) {
51  ucontext_t ucontext;
52  memset(&ucontext, 0, sizeof(ucontext));
53#if defined(__arm__)
54  ucontext.uc_mcontext.arm_r0 = unw_context.regs[0];
55  ucontext.uc_mcontext.arm_r1 = unw_context.regs[1];
56  ucontext.uc_mcontext.arm_r2 = unw_context.regs[2];
57  ucontext.uc_mcontext.arm_r3 = unw_context.regs[3];
58  ucontext.uc_mcontext.arm_r4 = unw_context.regs[4];
59  ucontext.uc_mcontext.arm_r5 = unw_context.regs[5];
60  ucontext.uc_mcontext.arm_r6 = unw_context.regs[6];
61  ucontext.uc_mcontext.arm_r7 = unw_context.regs[7];
62  ucontext.uc_mcontext.arm_r8 = unw_context.regs[8];
63  ucontext.uc_mcontext.arm_r9 = unw_context.regs[9];
64  ucontext.uc_mcontext.arm_r10 = unw_context.regs[10];
65  ucontext.uc_mcontext.arm_fp = unw_context.regs[11];
66  ucontext.uc_mcontext.arm_ip = unw_context.regs[12];
67  ucontext.uc_mcontext.arm_sp = unw_context.regs[13];
68  ucontext.uc_mcontext.arm_lr = unw_context.regs[14];
69  ucontext.uc_mcontext.arm_pc = unw_context.regs[15];
70#else
71  ucontext.uc_mcontext = unw_context.uc_mcontext;
72#endif
73  return ucontext;
74}
75
76static void OfflineBacktraceFunctionCall(std::function<int(void (*)(void*), void*)> function,
77                                         std::vector<uintptr_t>* pc_values) {
78  // Create a thread to generate the needed stack and registers information.
79  g_exit_flag = false;
80  const size_t stack_size = 1024 * 1024;
81  void* stack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
82  ASSERT_NE(MAP_FAILED, stack);
83  uintptr_t stack_addr = reinterpret_cast<uintptr_t>(stack);
84  pthread_attr_t attr;
85  ASSERT_EQ(0, pthread_attr_init(&attr));
86  ASSERT_EQ(0, pthread_attr_setstack(&attr, reinterpret_cast<void*>(stack), stack_size));
87  pthread_t thread;
88  OfflineThreadArg arg;
89  arg.function = function;
90  ASSERT_EQ(0, pthread_create(&thread, &attr, OfflineThreadFunc, &arg));
91  // Wait for the offline thread to generate the stack and unw_context information.
92  sleep(1);
93  // Copy the stack information.
94  std::vector<uint8_t> stack_data(reinterpret_cast<uint8_t*>(stack),
95                                  reinterpret_cast<uint8_t*>(stack) + stack_size);
96  g_exit_flag = true;
97  ASSERT_EQ(0, pthread_join(thread, nullptr));
98  ASSERT_EQ(0, munmap(stack, stack_size));
99
100  // Do offline backtrace.
101  std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid()));
102  ASSERT_TRUE(map != nullptr);
103
104  backtrace_stackinfo_t stack_info;
105  stack_info.start = stack_addr;
106  stack_info.end = stack_addr + stack_size;
107  stack_info.data = stack_data.data();
108
109  std::unique_ptr<Backtrace> backtrace(
110      Backtrace::CreateOffline(getpid(), arg.tid, map.get(), stack_info));
111  ASSERT_TRUE(backtrace != nullptr);
112
113  ucontext_t ucontext = GetUContextFromUnwContext(arg.unw_context);
114  ASSERT_TRUE(backtrace->Unwind(0, &ucontext));
115
116  // Collect pc values of the call stack frames.
117  for (size_t i = 0; i < backtrace->NumFrames(); ++i) {
118    pc_values->push_back(backtrace->GetFrame(i)->pc);
119  }
120}
121
122// Return the name of the function which matches the address. Although we don't know the
123// exact end of each function, it is accurate enough for the tests.
124static std::string FunctionNameForAddress(uintptr_t addr) {
125  struct FunctionSymbol {
126    std::string name;
127    uintptr_t start;
128    uintptr_t end;
129  };
130
131  static std::vector<FunctionSymbol> symbols;
132  if (symbols.empty()) {
133    symbols = std::vector<FunctionSymbol>{
134        {"unknown_start", 0, 0},
135        {"test_level_one", reinterpret_cast<uintptr_t>(&test_level_one), 0},
136        {"test_level_two", reinterpret_cast<uintptr_t>(&test_level_two), 0},
137        {"test_level_three", reinterpret_cast<uintptr_t>(&test_level_three), 0},
138        {"test_level_four", reinterpret_cast<uintptr_t>(&test_level_four), 0},
139        {"test_recursive_call", reinterpret_cast<uintptr_t>(&test_recursive_call), 0},
140        {"GetContextAndExit", reinterpret_cast<uintptr_t>(&GetContextAndExit), 0},
141        {"unknown_end", static_cast<uintptr_t>(-1), static_cast<uintptr_t>(-1)},
142    };
143    std::sort(
144        symbols.begin(), symbols.end(),
145        [](const FunctionSymbol& s1, const FunctionSymbol& s2) { return s1.start < s2.start; });
146    for (size_t i = 0; i + 1 < symbols.size(); ++i) {
147      symbols[i].end = symbols[i + 1].start;
148    }
149  }
150  for (auto& symbol : symbols) {
151    if (addr >= symbol.start && addr < symbol.end) {
152      return symbol.name;
153    }
154  }
155  return "";
156}
157
158TEST(libbacktrace, offline) {
159  std::function<int(void (*)(void*), void*)> function =
160      std::bind(test_level_one, 1, 2, 3, 4, std::placeholders::_1, std::placeholders::_2);
161  std::vector<uintptr_t> pc_values;
162  OfflineBacktraceFunctionCall(function, &pc_values);
163  ASSERT_FALSE(pc_values.empty());
164  ASSERT_LE(pc_values.size(), static_cast<size_t>(MAX_BACKTRACE_FRAMES));
165
166  size_t test_one_index = 0;
167  for (size_t i = 0; i < pc_values.size(); ++i) {
168    if (FunctionNameForAddress(pc_values[i]) == "test_level_one") {
169      test_one_index = i;
170      break;
171    }
172  }
173
174  ASSERT_GE(test_one_index, 3u);
175  ASSERT_EQ("test_level_one", FunctionNameForAddress(pc_values[test_one_index]));
176  ASSERT_EQ("test_level_two", FunctionNameForAddress(pc_values[test_one_index - 1]));
177  ASSERT_EQ("test_level_three", FunctionNameForAddress(pc_values[test_one_index - 2]));
178  ASSERT_EQ("test_level_four", FunctionNameForAddress(pc_values[test_one_index - 3]));
179}
180
181TEST(libbacktrace, offline_max_trace) {
182  std::function<int(void (*)(void*), void*)> function = std::bind(
183      test_recursive_call, MAX_BACKTRACE_FRAMES + 10, std::placeholders::_1, std::placeholders::_2);
184  std::vector<uintptr_t> pc_values;
185  OfflineBacktraceFunctionCall(function, &pc_values);
186  ASSERT_FALSE(pc_values.empty());
187  ASSERT_EQ(static_cast<size_t>(MAX_BACKTRACE_FRAMES), pc_values.size());
188  ASSERT_EQ("test_recursive_call", FunctionNameForAddress(pc_values.back()));
189}
190