summaryrefslogtreecommitdiff
path: root/absl/debugging/symbolize_test.cc
blob: c1090b8dc4372c6aa881adce2827b80c26dee694 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "absl/debugging/symbolize.h"

#ifndef _WIN32
#include <fcntl.h>
#include <sys/mman.h>
#endif

#include <cstring>
#include <iostream>
#include <memory>

#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
#include "absl/base/casts.h"
#include "absl/base/internal/per_thread_tls.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/optimization.h"
#include "absl/debugging/internal/stack_consumption.h"
#include "absl/memory/memory.h"

using testing::Contains;

// Functions to symbolize. Use C linkage to avoid mangled names.
extern "C" {
void nonstatic_func() { ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); }
static void static_func() { ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); }
}  // extern "C"

struct Foo {
  static void func(int x);
};

// A C++ method that should have a mangled name.
void ABSL_ATTRIBUTE_NOINLINE Foo::func(int) {
  ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
}

// Create functions that will remain in different text sections in the
// final binary when linker option "-z,keep-text-section-prefix" is used.
int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.unlikely) unlikely_func() {
  return 0;
}

int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.hot) hot_func() {
  return 0;
}

int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.startup) startup_func() {
  return 0;
}

int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text.exit) exit_func() {
  return 0;
}

int ABSL_ATTRIBUTE_SECTION_VARIABLE(.text) regular_func() {
  return 0;
}

// Thread-local data may confuse the symbolizer, ensure that it does not.
// Variable sizes and order are important.
#if ABSL_PER_THREAD_TLS
static ABSL_PER_THREAD_TLS_KEYWORD char symbolize_test_thread_small[1];
static ABSL_PER_THREAD_TLS_KEYWORD char
    symbolize_test_thread_big[2 * 1024 * 1024];
#endif

// Used below to hopefully inhibit some compiler/linker optimizations
// that may remove kHpageTextPadding, kPadding0, and kPadding1 from
// the binary.
static volatile bool volatile_bool = false;

// Force the binary to be large enough that a THP .text remap will succeed.
static constexpr size_t kHpageSize = 1 << 21;
const char kHpageTextPadding[kHpageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(
    ".text") = "";

static char try_symbolize_buffer[4096];

// A wrapper function for absl::Symbolize() to make the unit test simple.  The
// limit must be < sizeof(try_symbolize_buffer).  Returns null if
// absl::Symbolize() returns false, otherwise returns try_symbolize_buffer with
// the result of absl::Symbolize().
static const char *TrySymbolizeWithLimit(void *pc, int limit) {
  ABSL_RAW_CHECK(limit <= sizeof(try_symbolize_buffer),
                 "try_symbolize_buffer is too small");

  // Use the heap to facilitate heap and buffer sanitizer tools.
  auto heap_buffer = absl::make_unique<char[]>(sizeof(try_symbolize_buffer));
  bool found = absl::Symbolize(pc, heap_buffer.get(), limit);
  if (found) {
    ABSL_RAW_CHECK(strnlen(heap_buffer.get(), limit) < limit,
                   "absl::Symbolize() did not properly terminate the string");
    strncpy(try_symbolize_buffer, heap_buffer.get(),
            sizeof(try_symbolize_buffer));
  }

  return found ? try_symbolize_buffer : nullptr;
}

// A wrapper for TrySymbolizeWithLimit(), with a large limit.
static const char *TrySymbolize(void *pc) {
  return TrySymbolizeWithLimit(pc, sizeof(try_symbolize_buffer));
}

#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE

TEST(Symbolize, Cached) {
  // Compilers should give us pointers to them.
  EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));

  // The name of an internal linkage symbol is not specified; allow either a
  // mangled or an unmangled name here.
  const char *static_func_symbol = TrySymbolize((void *)(&static_func));
  EXPECT_TRUE(strcmp("static_func", static_func_symbol) == 0 ||
              strcmp("static_func()", static_func_symbol) == 0);

  EXPECT_TRUE(nullptr == TrySymbolize(nullptr));
}

TEST(Symbolize, Truncation) {
  constexpr char kNonStaticFunc[] = "nonstatic_func";
  EXPECT_STREQ("nonstatic_func",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) + 1));
  EXPECT_STREQ("nonstatic_...",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) + 0));
  EXPECT_STREQ("nonstatic...",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) - 1));
  EXPECT_STREQ("n...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 5));
  EXPECT_STREQ("...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 4));
  EXPECT_STREQ("..", TrySymbolizeWithLimit((void *)(&nonstatic_func), 3));
  EXPECT_STREQ(".", TrySymbolizeWithLimit((void *)(&nonstatic_func), 2));
  EXPECT_STREQ("", TrySymbolizeWithLimit((void *)(&nonstatic_func), 1));
  EXPECT_EQ(nullptr, TrySymbolizeWithLimit((void *)(&nonstatic_func), 0));
}

TEST(Symbolize, SymbolizeWithDemangling) {
  Foo::func(100);
  EXPECT_STREQ("Foo::func()", TrySymbolize((void *)(&Foo::func)));
}

TEST(Symbolize, SymbolizeSplitTextSections) {
  EXPECT_STREQ("unlikely_func()", TrySymbolize((void *)(&unlikely_func)));
  EXPECT_STREQ("hot_func()", TrySymbolize((void *)(&hot_func)));
  EXPECT_STREQ("startup_func()", TrySymbolize((void *)(&startup_func)));
  EXPECT_STREQ("exit_func()", TrySymbolize((void *)(&exit_func)));
  EXPECT_STREQ("regular_func()", TrySymbolize((void *)(&regular_func)));
}

// Tests that verify that Symbolize stack footprint is within some limit.
#ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION

static void *g_pc_to_symbolize;
static char g_symbolize_buffer[4096];
static char *g_symbolize_result;

static void SymbolizeSignalHandler(int signo) {
  if (absl::Symbolize(g_pc_to_symbolize, g_symbolize_buffer,
                      sizeof(g_symbolize_buffer))) {
    g_symbolize_result = g_symbolize_buffer;
  } else {
    g_symbolize_result = nullptr;
  }
}

// Call Symbolize and figure out the stack footprint of this call.
static const char *SymbolizeStackConsumption(void *pc, int *stack_consumed) {
  g_pc_to_symbolize = pc;
  *stack_consumed = absl::debugging_internal::GetSignalHandlerStackConsumption(
      SymbolizeSignalHandler);
  return g_symbolize_result;
}

static int GetStackConsumptionUpperLimit() {
  // Symbolize stack consumption should be within 2kB.
  int stack_consumption_upper_limit = 2048;
#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
    defined(THREAD_SANITIZER)
  // Account for sanitizer instrumentation requiring additional stack space.
  stack_consumption_upper_limit *= 5;
#endif
  return stack_consumption_upper_limit;
}

TEST(Symbolize, SymbolizeStackConsumption) {
  int stack_consumed = 0;

  const char *symbol =
      SymbolizeStackConsumption((void *)(&nonstatic_func), &stack_consumed);
  EXPECT_STREQ("nonstatic_func", symbol);
  EXPECT_GT(stack_consumed, 0);
  EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit());

  // The name of an internal linkage symbol is not specified; allow either a
  // mangled or an unmangled name here.
  symbol = SymbolizeStackConsumption((void *)(&static_func), &stack_consumed);
  EXPECT_TRUE(strcmp("static_func", symbol) == 0 ||
              strcmp("static_func()", symbol) == 0);
  EXPECT_GT(stack_consumed, 0);
  EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit());
}

TEST(Symbolize, SymbolizeWithDemanglingStackConsumption) {
  Foo::func(100);
  int stack_consumed = 0;

  const char *symbol =
      SymbolizeStackConsumption((void *)(&Foo::func), &stack_consumed);

  EXPECT_STREQ("Foo::func()", symbol);
  EXPECT_GT(stack_consumed, 0);
  EXPECT_LT(stack_consumed, GetStackConsumptionUpperLimit());
}

#endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION

// Use a 64K page size for PPC.
const size_t kPageSize = 64 << 10;
// We place a read-only symbols into the .text section and verify that we can
// symbolize them and other symbols after remapping them.
const char kPadding0[kPageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(".text") =
    "";
const char kPadding1[kPageSize * 4] ABSL_ATTRIBUTE_SECTION_VARIABLE(".text") =
    "";

static int FilterElfHeader(struct dl_phdr_info *info, size_t size, void *data) {
  for (int i = 0; i < info->dlpi_phnum; i++) {
    if (info->dlpi_phdr[i].p_type == PT_LOAD &&
        info->dlpi_phdr[i].p_flags == (PF_R | PF_X)) {
      const void *const vaddr =
          absl::bit_cast<void *>(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
      const auto segsize = info->dlpi_phdr[i].p_memsz;

      const char *self_exe;
      if (info->dlpi_name != nullptr && info->dlpi_name[0] != '\0') {
        self_exe = info->dlpi_name;
      } else {
        self_exe = "/proc/self/exe";
      }

      absl::debugging_internal::RegisterFileMappingHint(
          vaddr, reinterpret_cast<const char *>(vaddr) + segsize,
          info->dlpi_phdr[i].p_offset, self_exe);

      return 1;
    }
  }

  return 1;
}

TEST(Symbolize, SymbolizeWithMultipleMaps) {
  // Force kPadding0 and kPadding1 to be linked in.
  if (volatile_bool) {
    ABSL_RAW_LOG(INFO, "%s", kPadding0);
    ABSL_RAW_LOG(INFO, "%s", kPadding1);
  }

  // Verify we can symbolize everything.
  char buf[512];
  memset(buf, 0, sizeof(buf));
  absl::Symbolize(kPadding0, buf, sizeof(buf));
  EXPECT_STREQ("kPadding0", buf);

  memset(buf, 0, sizeof(buf));
  absl::Symbolize(kPadding1, buf, sizeof(buf));
  EXPECT_STREQ("kPadding1", buf);

  // Specify a hint for the executable segment.
  dl_iterate_phdr(FilterElfHeader, nullptr);

  // Reload at least one page out of kPadding0, kPadding1
  const char *ptrs[] = {kPadding0, kPadding1};

  for (const char *ptr : ptrs) {
    const int kMapFlags = MAP_ANONYMOUS | MAP_PRIVATE;
    void *addr = mmap(nullptr, kPageSize, PROT_READ, kMapFlags, 0, 0);
    ASSERT_NE(addr, MAP_FAILED);

    // kPadding[0-1] is full of zeroes, so we can remap anywhere within it, but
    // we ensure there is at least a full page of padding.
    void *remapped = reinterpret_cast<void *>(
        reinterpret_cast<uintptr_t>(ptr + kPageSize) & ~(kPageSize - 1ULL));

    const int kMremapFlags = (MREMAP_MAYMOVE | MREMAP_FIXED);
    void *ret = mremap(addr, kPageSize, kPageSize, kMremapFlags, remapped);
    ASSERT_NE(ret, MAP_FAILED);
  }

  // Invalidate the symbolization cache so we are forced to rely on the hint.
  absl::Symbolize(nullptr, buf, sizeof(buf));

  // Verify we can still symbolize.
  const char *expected[] = {"kPadding0", "kPadding1"};
  const size_t offsets[] = {0, kPageSize, 2 * kPageSize, 3 * kPageSize};

  for (int i = 0; i < 2; i++) {
    for (size_t offset : offsets) {
      memset(buf, 0, sizeof(buf));
      absl::Symbolize(ptrs[i] + offset, buf, sizeof(buf));
      EXPECT_STREQ(expected[i], buf);
    }
  }
}

// Appends std::string(*args->arg) to args->symbol_buf.
static void DummySymbolDecorator(
    const absl::debugging_internal::SymbolDecoratorArgs *args) {
  std::string *message = static_cast<std::string *>(args->arg);
  strncat(args->symbol_buf, message->c_str(),
          args->symbol_buf_size - strlen(args->symbol_buf) - 1);
}

TEST(Symbolize, InstallAndRemoveSymbolDecorators) {
  int ticket_a;
  std::string a_message("a");
  EXPECT_GE(ticket_a = absl::debugging_internal::InstallSymbolDecorator(
                DummySymbolDecorator, &a_message),
            0);

  int ticket_b;
  std::string b_message("b");
  EXPECT_GE(ticket_b = absl::debugging_internal::InstallSymbolDecorator(
                DummySymbolDecorator, &b_message),
            0);

  int ticket_c;
  std::string c_message("c");
  EXPECT_GE(ticket_c = absl::debugging_internal::InstallSymbolDecorator(
                DummySymbolDecorator, &c_message),
            0);

  char *address = reinterpret_cast<char *>(1);
  EXPECT_STREQ("abc", TrySymbolize(address++));

  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_b));

  EXPECT_STREQ("ac", TrySymbolize(address++));

  // Cleanup: remove all remaining decorators so other stack traces don't
  // get mystery "ac" decoration.
  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_a));
  EXPECT_TRUE(absl::debugging_internal::RemoveSymbolDecorator(ticket_c));
}

// Some versions of Clang with optimizations enabled seem to be able
// to optimize away the .data section if no variables live in the
// section. This variable should get placed in the .data section, and
// the test below checks for the existence of a .data section.
static int in_data_section = 1;

TEST(Symbolize, ForEachSection) {
  int fd = TEMP_FAILURE_RETRY(open("/proc/self/exe", O_RDONLY));
  ASSERT_NE(fd, -1);

  std::vector<std::string> sections;
  ASSERT_TRUE(absl::debugging_internal::ForEachSection(
      fd, [&sections](const std::string &name, const ElfW(Shdr) &) {
        sections.push_back(name);
        return true;
      }));

  // Check for the presence of common section names.
  EXPECT_THAT(sections, Contains(".text"));
  EXPECT_THAT(sections, Contains(".rodata"));
  EXPECT_THAT(sections, Contains(".bss"));
  ++in_data_section;
  EXPECT_THAT(sections, Contains(".data"));

  close(fd);
}

// x86 specific tests.  Uses some inline assembler.
extern "C" {
inline void *ABSL_ATTRIBUTE_ALWAYS_INLINE inline_func() {
  void *pc = nullptr;
#if defined(__i386__) || defined(__x86_64__)
  __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
#endif
  return pc;
}

void *ABSL_ATTRIBUTE_NOINLINE non_inline_func() {
  void *pc = nullptr;
#if defined(__i386__) || defined(__x86_64__)
  __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
#endif
  return pc;
}

void ABSL_ATTRIBUTE_NOINLINE TestWithPCInsideNonInlineFunction() {
#if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE) && \
    (defined(__i386__) || defined(__x86_64__))
  void *pc = non_inline_func();
  const char *symbol = TrySymbolize(pc);
  ABSL_RAW_CHECK(symbol != nullptr, "TestWithPCInsideNonInlineFunction failed");
  ABSL_RAW_CHECK(strcmp(symbol, "non_inline_func") == 0,
                 "TestWithPCInsideNonInlineFunction failed");
  std::cout << "TestWithPCInsideNonInlineFunction passed" << std::endl;
#endif
}

void ABSL_ATTRIBUTE_NOINLINE TestWithPCInsideInlineFunction() {
#if defined(ABSL_HAVE_ATTRIBUTE_ALWAYS_INLINE) && \
    (defined(__i386__) || defined(__x86_64__))
  void *pc = inline_func();  // Must be inlined.
  const char *symbol = TrySymbolize(pc);
  ABSL_RAW_CHECK(symbol != nullptr, "TestWithPCInsideInlineFunction failed");
  ABSL_RAW_CHECK(strcmp(symbol, __FUNCTION__) == 0,
                 "TestWithPCInsideInlineFunction failed");
  std::cout << "TestWithPCInsideInlineFunction passed" << std::endl;
#endif
}
}

// Test with a return address.
void ABSL_ATTRIBUTE_NOINLINE TestWithReturnAddress() {
#if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE)
  void *return_address = __builtin_return_address(0);
  const char *symbol = TrySymbolize(return_address);
  ABSL_RAW_CHECK(symbol != nullptr, "TestWithReturnAddress failed");
  ABSL_RAW_CHECK(strcmp(symbol, "main") == 0, "TestWithReturnAddress failed");
  std::cout << "TestWithReturnAddress passed" << std::endl;
#endif
}

#elif defined(_WIN32) && defined(_DEBUG)

TEST(Symbolize, Basics) {
  EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));

  // The name of an internal linkage symbol is not specified; allow either a
  // mangled or an unmangled name here.
  const char* static_func_symbol = TrySymbolize((void *)(&static_func));
  ASSERT_TRUE(static_func_symbol != nullptr);
  EXPECT_TRUE(strstr(static_func_symbol, "static_func") != nullptr);

  EXPECT_TRUE(nullptr == TrySymbolize(nullptr));
}

TEST(Symbolize, Truncation) {
  constexpr char kNonStaticFunc[] = "nonstatic_func";
  EXPECT_STREQ("nonstatic_func",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) + 1));
  EXPECT_STREQ("nonstatic_...",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) + 0));
  EXPECT_STREQ("nonstatic...",
               TrySymbolizeWithLimit((void *)(&nonstatic_func),
                                     strlen(kNonStaticFunc) - 1));
  EXPECT_STREQ("n...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 5));
  EXPECT_STREQ("...", TrySymbolizeWithLimit((void *)(&nonstatic_func), 4));
  EXPECT_STREQ("..", TrySymbolizeWithLimit((void *)(&nonstatic_func), 3));
  EXPECT_STREQ(".", TrySymbolizeWithLimit((void *)(&nonstatic_func), 2));
  EXPECT_STREQ("", TrySymbolizeWithLimit((void *)(&nonstatic_func), 1));
  EXPECT_EQ(nullptr, TrySymbolizeWithLimit((void *)(&nonstatic_func), 0));
}

TEST(Symbolize, SymbolizeWithDemangling) {
  const char* result = TrySymbolize((void *)(&Foo::func));
  ASSERT_TRUE(result != nullptr);
  EXPECT_TRUE(strstr(result, "Foo::func") != nullptr) << result;
}

#else  // Symbolizer unimplemented

TEST(Symbolize, Unimplemented) {
  char buf[64];
  EXPECT_FALSE(absl::Symbolize((void *)(&nonstatic_func), buf, sizeof(buf)));
  EXPECT_FALSE(absl::Symbolize((void *)(&static_func), buf, sizeof(buf)));
  EXPECT_FALSE(absl::Symbolize((void *)(&Foo::func), buf, sizeof(buf)));
}

#endif

int main(int argc, char **argv) {
  // Make sure kHpageTextPadding is linked into the binary.
  if (volatile_bool) {
    ABSL_RAW_LOG(INFO, "%s", kHpageTextPadding);
  }

#if ABSL_PER_THREAD_TLS
  // Touch the per-thread variables.
  symbolize_test_thread_small[0] = 0;
  symbolize_test_thread_big[0] = 0;
#endif

  absl::InitializeSymbolizer(argv[0]);
  testing::InitGoogleTest(&argc, argv);

#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
  TestWithPCInsideInlineFunction();
  TestWithPCInsideNonInlineFunction();
  TestWithReturnAddress();
#endif

  return RUN_ALL_TESTS();
}