helgrind/tests/safe-pthread.h

   1 #include <pthread.h>
   2 #include <signal.h>
   3 #include <setjmp.h>
   4 #include <errno.h>
   5 #include <assert.h>
   6
   7 static sigjmp_buf env;
   8
   9 /*
  10  * Starting with glibc 2.20 some pthread calls may execute
  11  * an xend instruction unconditionally when a lock is used in
  12  * a way that is invalid so defined a sigill handler that can
  13  * convert these invalid instructions to a normal error.
  14  */
  15 static void sigill_handler( int signum, siginfo_t *siginfo, void *sigcontext ) {
  16    unsigned char *pc = siginfo->si_addr;
  17    assert( pc[0] == 0x0f && pc[1] == 0x01 && pc[2] == 0xd5 );
  18    siglongjmp( env, EPERM );
  19 }
  20
  21 /*
  22  * Same as above, but in case we do recognize the xend,
  23  * but detect it is invalid (used outside a transaction)
  24  * and generate a segv.  Unfortunately then si_addr is,
  25  * just zero, so we cannot add an assert/sanity check.
  26  */
  27 static void segv_handler( int signum, siginfo_t *siginfo, void *sigcontext ) {
  28    siglongjmp( env, EPERM );
  29 }
  30
  31 /*
  32  * Wrapper for pthread_rwlock_unlock which may execute xend
  33  * unconditionally when used on a lock that is not locked.
  34  *
  35  * Note that we return 0 instead of EPERM because that is what
  36  * glibc normally does - error reporting is optional.
  37  */
  38 static int safe_pthread_rwlock_unlock( pthread_rwlock_t *rwlock ) {
  39    struct sigaction sa_ill, sa_segv;
  40    struct sigaction oldsa_ill, oldsa_segv;
  41    int r;
  42
  43    sa_ill.sa_handler = NULL;
  44    sa_ill.sa_sigaction = sigill_handler;
  45    sigemptyset( &sa_ill.sa_mask );
  46    sa_ill.sa_flags = SA_SIGINFO;
  47
  48    sigaction( SIGILL, &sa_ill, &oldsa_ill );
  49
  50    sa_segv.sa_handler = NULL;
  51    sa_segv.sa_sigaction = segv_handler;
  52    sigemptyset( &sa_segv.sa_mask );
  53    sa_segv.sa_flags = SA_SIGINFO;
  54
  55    sigaction( SIGSEGV, &sa_segv, &oldsa_segv );
  56
  57    if ( ( r = sigsetjmp( env, 1 ) ) == 0 ) {
  58      r = pthread_rwlock_unlock( rwlock );
  59    } else {
  60      r = 0;
  61    }
  62
  63    sigaction( SIGILL, &oldsa_ill, NULL );
  64    sigaction( SIGSEGV, &oldsa_segv, NULL );
  65
  66    return r;
  67 }
  68
  69 #define pthread_rwlock_unlock safe_pthread_rwlock_unlock