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30 // Author: Satoru Takabayashi
32 // Unit tests for functions in symbolize.cc.
34 #include "utilities.h"
39 #include "glog/logging.h"
40 #include "symbolize.h"
41 #include "googletest.h"
44 #ifdef HAVE_LIB_GFLAGS
45 #include <gflags/gflags.h>
46 using namespace GFLAGS_NAMESPACE;
50 using namespace GOOGLE_NAMESPACE;
52 #if defined(HAVE_STACKTRACE) && defined(__ELF__)
56 // This unit tests make sense only with GCC.
57 // Uses lots of GCC specific features.
58 #if defined(__GNUC__) && !defined(__OPENCC__)
60 # define TEST_WITH_MODERN_GCC
61 # if __i386__ // always_inline isn't supported for x86_64 with GCC 4.1.0.
63 # define always_inline __attribute__((always_inline))
64 # define HAVE_ALWAYS_INLINE
67 # endif // __GNUC__ >= 4
68 # if defined(__i386__) || defined(__x86_64__)
69 # define TEST_X86_32_AND_64 1
70 # endif // defined(__i386__) || defined(__x86_64__)
73 // A wrapper function for Symbolize() to make the unit test simple.
74 static const char *TrySymbolize(void *pc) {
75 static char symbol[4096];
76 if (Symbolize(pc, symbol, sizeof(symbol))) {
83 // Make them C linkage to avoid mangled names.
85 void nonstatic_func() {
90 static void static_func() {
96 TEST(Symbolize, Symbolize) {
97 // We do C-style cast since GCC 2.95.3 doesn't allow
98 // reinterpret_cast<void *>(&func).
100 // Compilers should give us pointers to them.
101 EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));
103 // The name of an internal linkage symbol is not specified; allow either a
104 // mangled or an unmangled name here.
105 const char *static_func_symbol = TrySymbolize((void *)(&static_func));
106 CHECK(NULL != static_func_symbol);
107 EXPECT_TRUE(strcmp("static_func", static_func_symbol) == 0 ||
108 strcmp("static_func()", static_func_symbol) == 0);
110 EXPECT_TRUE(NULL == TrySymbolize(NULL));
114 static void func(int x);
117 void ATTRIBUTE_NOINLINE Foo::func(int x) {
122 // With a modern GCC, Symbolize() should return demangled symbol
123 // names. Function parameters should be omitted.
124 #ifdef TEST_WITH_MODERN_GCC
125 TEST(Symbolize, SymbolizeWithDemangling) {
127 EXPECT_STREQ("Foo::func()", TrySymbolize((void *)(&Foo::func)));
131 // Tests that verify that Symbolize footprint is within some limit.
133 // To measure the stack footprint of the Symbolize function, we create
134 // a signal handler (for SIGUSR1 say) that calls the Symbolize function
135 // on an alternate stack. This alternate stack is initialized to some
136 // known pattern (0x55, 0x55, 0x55, ...). We then self-send this signal,
137 // and after the signal handler returns, look at the alternate stack
138 // buffer to see what portion has been touched.
140 // This trick gives us the the stack footprint of the signal handler.
141 // But the signal handler, even before the call to Symbolize, consumes
142 // some stack already. We however only want the stack usage of the
143 // Symbolize function. To measure this accurately, we install two signal
144 // handlers: one that does nothing and just returns, and another that
145 // calls Symbolize. The difference between the stack consumption of these
146 // two signals handlers should give us the Symbolize stack foorprint.
148 static void *g_pc_to_symbolize;
149 static char g_symbolize_buffer[4096];
150 static char *g_symbolize_result;
152 static void EmptySignalHandler(int signo) {}
154 static void SymbolizeSignalHandler(int signo) {
155 if (Symbolize(g_pc_to_symbolize, g_symbolize_buffer,
156 sizeof(g_symbolize_buffer))) {
157 g_symbolize_result = g_symbolize_buffer;
159 g_symbolize_result = NULL;
163 const int kAlternateStackSize = 8096;
164 const char kAlternateStackFillValue = 0x55;
166 // These helper functions look at the alternate stack buffer, and figure
167 // out what portion of this buffer has been touched - this is the stack
168 // consumption of the signal handler running on this alternate stack.
169 static ATTRIBUTE_NOINLINE bool StackGrowsDown(int *x) {
173 static int GetStackConsumption(const char* alt_stack) {
175 if (StackGrowsDown(&x)) {
176 for (int i = 0; i < kAlternateStackSize; i++) {
177 if (alt_stack[i] != kAlternateStackFillValue) {
178 return (kAlternateStackSize - i);
182 for (int i = (kAlternateStackSize - 1); i >= 0; i--) {
183 if (alt_stack[i] != kAlternateStackFillValue) {
191 #ifdef HAVE_SIGALTSTACK
193 // Call Symbolize and figure out the stack footprint of this call.
194 static const char *SymbolizeStackConsumption(void *pc, int *stack_consumed) {
196 g_pc_to_symbolize = pc;
198 // The alt-signal-stack cannot be heap allocated because there is a
199 // bug in glibc-2.2 where some signal handler setup code looks at the
200 // current stack pointer to figure out what thread is currently running.
201 // Therefore, the alternate stack must be allocated from the main stack
203 char altstack[kAlternateStackSize];
204 memset(altstack, kAlternateStackFillValue, kAlternateStackSize);
206 // Set up the alt-signal-stack (and save the older one).
208 memset(&sigstk, 0, sizeof(stack_t));
210 sigstk.ss_sp = altstack;
211 sigstk.ss_size = kAlternateStackSize;
213 CHECK_ERR(sigaltstack(&sigstk, &old_sigstk));
215 // Set up SIGUSR1 and SIGUSR2 signal handlers (and save the older ones).
217 memset(&sa, 0, sizeof(struct sigaction));
218 struct sigaction old_sa1, old_sa2;
219 sigemptyset(&sa.sa_mask);
220 sa.sa_flags = SA_ONSTACK;
222 // SIGUSR1 maps to EmptySignalHandler.
223 sa.sa_handler = EmptySignalHandler;
224 CHECK_ERR(sigaction(SIGUSR1, &sa, &old_sa1));
226 // SIGUSR2 maps to SymbolizeSignalHanlder.
227 sa.sa_handler = SymbolizeSignalHandler;
228 CHECK_ERR(sigaction(SIGUSR2, &sa, &old_sa2));
230 // Send SIGUSR1 signal and measure the stack consumption of the empty
232 CHECK_ERR(kill(getpid(), SIGUSR1));
233 int stack_consumption1 = GetStackConsumption(altstack);
235 // Send SIGUSR2 signal and measure the stack consumption of the symbolize
237 CHECK_ERR(kill(getpid(), SIGUSR2));
238 int stack_consumption2 = GetStackConsumption(altstack);
240 // The difference between the two stack consumption values is the
241 // stack footprint of the Symbolize function.
242 if (stack_consumption1 != -1 && stack_consumption2 != -1) {
243 *stack_consumed = stack_consumption2 - stack_consumption1;
245 *stack_consumed = -1;
248 // Log the stack consumption values.
249 LOG(INFO) << "Stack consumption of empty signal handler: "
250 << stack_consumption1;
251 LOG(INFO) << "Stack consumption of symbolize signal handler: "
252 << stack_consumption2;
253 LOG(INFO) << "Stack consumption of Symbolize: " << *stack_consumed;
255 // Now restore the old alt-signal-stack and signal handlers.
256 CHECK_ERR(sigaltstack(&old_sigstk, NULL));
257 CHECK_ERR(sigaction(SIGUSR1, &old_sa1, NULL));
258 CHECK_ERR(sigaction(SIGUSR2, &old_sa2, NULL));
260 return g_symbolize_result;
263 // Symbolize stack consumption should be within 2kB.
264 const int kStackConsumptionUpperLimit = 2048;
266 TEST(Symbolize, SymbolizeStackConsumption) {
270 symbol = SymbolizeStackConsumption((void *)(&nonstatic_func),
272 EXPECT_STREQ("nonstatic_func", symbol);
273 EXPECT_GT(stack_consumed, 0);
274 EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
276 // The name of an internal linkage symbol is not specified; allow either a
277 // mangled or an unmangled name here.
278 symbol = SymbolizeStackConsumption((void *)(&static_func),
280 CHECK(NULL != symbol);
281 EXPECT_TRUE(strcmp("static_func", symbol) == 0 ||
282 strcmp("static_func()", symbol) == 0);
283 EXPECT_GT(stack_consumed, 0);
284 EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
287 #ifdef TEST_WITH_MODERN_GCC
288 TEST(Symbolize, SymbolizeWithDemanglingStackConsumption) {
293 symbol = SymbolizeStackConsumption((void *)(&Foo::func), &stack_consumed);
295 EXPECT_STREQ("Foo::func()", symbol);
296 EXPECT_GT(stack_consumed, 0);
297 EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
301 #endif // HAVE_SIGALTSTACK
303 // x86 specific tests. Uses some inline assembler.
305 inline void* always_inline inline_func() {
306 register void *pc = NULL;
307 #ifdef TEST_X86_32_AND_64
308 __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
313 void* ATTRIBUTE_NOINLINE non_inline_func() {
314 register void *pc = NULL;
315 #ifdef TEST_X86_32_AND_64
316 __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
321 void ATTRIBUTE_NOINLINE TestWithPCInsideNonInlineFunction() {
322 #if defined(TEST_X86_32_AND_64) && defined(HAVE_ATTRIBUTE_NOINLINE)
323 void *pc = non_inline_func();
324 const char *symbol = TrySymbolize(pc);
325 CHECK(symbol != NULL);
326 CHECK_STREQ(symbol, "non_inline_func");
327 cout << "Test case TestWithPCInsideNonInlineFunction passed." << endl;
331 void ATTRIBUTE_NOINLINE TestWithPCInsideInlineFunction() {
332 #if defined(TEST_X86_32_AND_64) && defined(HAVE_ALWAYS_INLINE)
333 void *pc = inline_func(); // Must be inlined.
334 const char *symbol = TrySymbolize(pc);
335 CHECK(symbol != NULL);
336 CHECK_STREQ(symbol, __FUNCTION__);
337 cout << "Test case TestWithPCInsideInlineFunction passed." << endl;
342 // Test with a return address.
343 void ATTRIBUTE_NOINLINE TestWithReturnAddress() {
344 #if defined(HAVE_ATTRIBUTE_NOINLINE)
345 void *return_address = __builtin_return_address(0);
346 const char *symbol = TrySymbolize(return_address);
347 CHECK(symbol != NULL);
348 CHECK_STREQ(symbol, "main");
349 cout << "Test case TestWithReturnAddress passed." << endl;
353 int main(int argc, char **argv) {
354 FLAGS_logtostderr = true;
355 InitGoogleLogging(argv[0]);
356 InitGoogleTest(&argc, argv);
357 #ifdef HAVE_SYMBOLIZE
358 // We don't want to get affected by the callback interface, that may be
359 // used to install some callback function at InitGoogle() time.
360 InstallSymbolizeCallback(NULL);
362 TestWithPCInsideInlineFunction();
363 TestWithPCInsideNonInlineFunction();
364 TestWithReturnAddress();
365 return RUN_ALL_TESTS();
373 #ifdef HAVE_SYMBOLIZE
374 printf("PASS (no symbolize_unittest support)\n");
376 printf("PASS (no symbolize support)\n");
380 #endif // HAVE_STACKTRACE