memcheck/tests/arm64/bug484935.c

   1 #include <assert.h>
   2 #include <signal.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <sys/time.h>
   6
   7 static void signalHandler(int sig, siginfo_t* info, void* uctx_v)
   8 {
   9    if (sig != SIGALRM)
  10       abort();
  11    if (info == 0)
  12       abort();
  13    if (uctx_v == 0)
  14       abort();
  15 }
  16
  17 void* load_memory_content(void** ptr)
  18 {
  19    void* result;
  20    __asm__ volatile(
  21       // load x0, x1, x2 with data from ptr, and loop for a while. If we get
  22       // a signal in the loop, these registers have uninitialized data in
  23       // them, but should be valid inside the signal handler. Without our
  24       // patch, valgrind complains. We can remove the individual lines from
  25       // the patch, and see each argument in turn affecting valgrind
  26       "LDR x0, [%1]\n"
  27       "LDR x1, [%1, #8]\n"
  28       "LDR x2, [%1, #16]\n"
  29       "mov %0, x0\n"
  30       "mov x3, #2000\n"
  31       "loop:"
  32       " subs x3, x3, #1\n"
  33       " b.ne loop\n"
  34       : "=r"(result)
  35       : "r"(ptr)
  36       : "x0", "x1", "x2", "x3");
  37    return result;
  38 }
  39
  40 int main()
  41 {
  42    struct sigaction sa;
  43    memset(&sa, 0, sizeof sa);
  44    sa.sa_flags     = SA_SIGINFO;
  45    sa.sa_sigaction = signalHandler;
  46    int rc          = sigaction(SIGALRM, &sa, 0);
  47    assert(rc == 0);
  48    struct itimerval timer = {{0, 1000}, {0, 1000}};
  49    setitimer(ITIMER_REAL, &timer, 0);
  50    void** q = malloc(100);
  51    for (int i = 0; i < 1000; ++i)
  52       load_memory_content(q);
  53 }