compiler-rt/test/tsan/Linux/dlopen_static_tls.cpp

   1 // RUN: %clangxx_tsan -O1 %s -DBUILD_SO -fPIC -shared -o %t-so.so
   2 // RUN: %clangxx_tsan -O1 %s %link_libcxx_tsan -o %t && %run %t 2>&1 | FileCheck %s
   3
   4 // A test for loading a dynamic library with static TLS.
   5 // Such static TLS is a hack that allows a dynamic library to have faster TLS,
   6 // but it can be loaded only iff all threads happened to allocate some excess
   7 // of static TLS space for whatever reason. If it's not the case loading fails with:
   8 // dlopen: cannot load any more object with static TLS
   9 // We used to produce a false positive because dlopen will write into TLS
  10 // of all existing threads to initialize/zero TLS region for the loaded library.
  11 // And this appears to be racing with initialization of TLS in the thread
  12 // since we model a write into the whole static TLS region (we don't know what part
  13 // of it is currently unused):
  14 // WARNING: ThreadSanitizer: data race (pid=2317365)
  15 //   Write of size 1 at 0x7f1fa9bfcdd7 by main thread:
  16 //     #0 memset
  17 //     #1 init_one_static_tls
  18 //     #2 __pthread_init_static_tls
  19 //     [[ this is where main calls dlopen ]]
  20 //     #3 main
  21 //   Previous write of size 8 at 0x7f1fa9bfcdd0 by thread T1:
  22 //     #0 __tsan_tls_initialization
  23
  24 // Failing on bots:
  25 // https://lab.llvm.org/buildbot#builders/184/builds/1580
  26 // https://lab.llvm.org/buildbot#builders/18/builds/3167
  27 // UNSUPPORTED: target={{(aarch64|powerpc64).*}}
  28
  29 #ifdef BUILD_SO
  30
  31 __attribute__((tls_model("initial-exec"))) __thread char x = 42;
  32 __attribute__((tls_model("initial-exec"))) __thread char y;
  33
  34 extern "C" int sofunc() { return ++x + ++y; }
  35
  36 #else // BUILD_SO
  37
  38 #  include "../test.h"
  39 #  include <dlfcn.h>
  40 #  include <string>
  41
  42 __thread int x[1023];
  43
  44 void *lib;
  45 void (*func)();
  46 int ready;
  47
  48 void *thread(void *arg) {
  49   barrier_wait(&barrier);
  50   if (__atomic_load_n(&ready, __ATOMIC_ACQUIRE))
  51     func();
  52   barrier_wait(&barrier);
  53   if (dlclose(lib)) {
  54     printf("error in dlclose: %s\n", dlerror());
  55     exit(1);
  56   }
  57   return 0;
  58 }
  59
  60 int main(int argc, char *argv[]) {
  61   barrier_init(&barrier, 2);
  62   pthread_t th;
  63   pthread_create(&th, 0, thread, 0);
  64   lib = dlopen((std::string(argv[0]) + "-so.so").c_str(), RTLD_NOW);
  65   if (lib == 0) {
  66     printf("error in dlopen: %s\n", dlerror());
  67     return 1;
  68   }
  69   func = (void (*)())dlsym(lib, "sofunc");
  70   if (func == 0) {
  71     printf("error in dlsym: %s\n", dlerror());
  72     return 1;
  73   }
  74   __atomic_store_n(&ready, 1, __ATOMIC_RELEASE);
  75   barrier_wait(&barrier);
  76   func();
  77   barrier_wait(&barrier);
  78   pthread_join(th, 0);
  79   fprintf(stderr, "DONE\n");
  80   return 0;
  81 }
  82
  83 #endif // BUILD_SO
  84
  85 // CHECK: DONE