lldb/test/Shell/Register/Inputs/x86-multithread-write.cpp

   1 #include <cinttypes>
   2 #include <cstdint>
   3 #include <cstdio>
   4 #include <mutex>
   5 #include <thread>
   6
   7 std::mutex t1_mutex, t2_mutex;
   8
   9 struct test_data {
  10   uint32_t eax;
  11   uint32_t ebx;
  12
  13   struct alignas(16) {
  14     uint8_t data[10];
  15   } st0;
  16 };
  17
  18 constexpr test_data filler = {
  19   .eax = 0xffffffff,
  20   .ebx = 0xffffffff,
  21   .st0 = {{0x1f, 0x2f, 0x3f, 0x4f, 0x5f, 0x6f, 0x7f, 0x8f, 0x80, 0x40}},
  22 };
  23
  24 void t_func(std::mutex &t_mutex) {
  25   std::lock_guard<std::mutex> t_lock(t_mutex);
  26   test_data out = filler;
  27
  28   asm volatile(
  29     "finit\t\n"
  30     "fldt %2\t\n"
  31     "int3\n\t"
  32     "fstpt %2\t\n"
  33     : "+a"(out.eax), "+b"(out.ebx)
  34     : "m"(out.st0)
  35     : "memory", "st"
  36   );
  37
  38   printf("eax = 0x%08" PRIx32 "\n", out.eax);
  39   printf("ebx = 0x%08" PRIx32 "\n", out.ebx);
  40   printf("st0 = { ");
  41   for (int i = 0; i < sizeof(out.st0.data); ++i)
  42     printf("0x%02" PRIx8 " ", out.st0.data[i]);
  43   printf("}\n");
  44 }
  45
  46 int main() {
  47   // block both threads from proceeding
  48   std::unique_lock<std::mutex> m1_lock(t1_mutex);
  49   std::unique_lock<std::mutex> m2_lock(t2_mutex);
  50
  51   // start both threads
  52   std::thread t1(t_func, std::ref(t1_mutex));
  53   std::thread t2(t_func, std::ref(t2_mutex));
  54
  55   // release lock on thread 1 to make it interrupt the program
  56   m1_lock.unlock();
  57   // wait for thread 1 to finish
  58   t1.join();
  59
  60   // release lock on thread 2
  61   m2_lock.unlock();
  62   // wait for thread 2 to finish
  63   t2.join();
  64
  65   return 0;
  66 }