Implement GetTls() for NetBSD

[krytarowski]

Summary

Reuse the existing code for FreeBSD that is compatible with NetBSD.

Add NetBSD support in tests: tls_race.cc and tls_race2.cc.

Sponsored by <The NetBSD Foundation>

[krytarowski]

Verification from @joerg is welcome.

[krytarowski]

This patch also helps MSan/NetBSD.. and perhaps is the reason why MSan started to work better - modulo this DEADLYSIGNAL that plagues sanitizers on NetBSD.

http://www.netbsd.org/~kamil/llvm/msan.txt

[joerg]

lib/sanitizer_common/sanitizer_linux_libcdep.cc

319

Please follow ld.elf_so/tls.c here and use _lwp_setprivate/_lwp_settcb for consistent behavior across all platforms.

355

It would be better to use struct tls_tcb from sys/tls.h here, avoids having to distinguish variant I and variant II.

[krytarowski]

lib/sanitizer_common/sanitizer_linux_libcdep.cc

319

D40159

355

D40159

lib/sanitizer_common/sanitizer_linux_libcdep.cc

# elif defined(__powerpc64__)
   descr_addr = thread_pointer - TlsPreTcbSize();
 # else
 #  error "unsupported CPU arch"
 # endif
   return descr_addr;
 }
 #endif  // (x86_64 || i386 || MIPS) && SANITIZER_LINUX
 
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD
 static void **ThreadSelfSegbase() {
   void **segbase = 0;
 # if defined(__i386__)
   // sysarch(I386_GET_GSBASE, segbase);
   __asm __volatile("mov %%gs:0, %0" : "=r" (segbase));
 # elif defined(__x86_64__)
   // sysarch(AMD64_GET_FSBASE, segbase);
   __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
 # else
-#  error "unsupported CPU arch for FreeBSD platform"
+#  error "unsupported CPU arch"
 # endif
   return segbase;
 }
 
 uptr ThreadSelf() {
   return (uptr)ThreadSelfSegbase()[2];
 }
-#elif SANITIZER_NETBSD
-uptr ThreadSelf() { return (uptr)pthread_self(); }
-#endif  // SANITIZER_NETBSD
+#endif  // SANITIZER_FREEBSD || SANITIZER_NETBSD
 
 #if !SANITIZER_GO
 static void GetTls(uptr *addr, uptr *size) {
 #if SANITIZER_LINUX && !SANITIZER_ANDROID
 # if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
   *addr = ThreadSelf();
   *size = GetTlsSize();
   *addr -= *size;
   *addr += ThreadDescriptorSize();
 # elif defined(__mips__) || defined(__aarch64__) || defined(__powerpc64__) \
     || defined(__arm__)
   *addr = ThreadSelf();
   *size = GetTlsSize();
 # else
   *addr = 0;
   *size = 0;
 # endif
-#elif SANITIZER_FREEBSD
+#elif SANITIZER_FREEBSD || SANITIZER_NETBSD
   void** segbase = ThreadSelfSegbase();
   *addr = 0;
   *size = 0;
   if (segbase != 0) {
     // tcbalign = 16
     // tls_size = round(tls_static_space, tcbalign);
     // dtv = segbase[1];
     // dtv[2] = segbase - tls_static_space;
     void **dtv = (void**) segbase[1];
     *addr = (uptr) dtv[2];
     *size = (*addr == 0) ? 0 : ((uptr) segbase[0] - (uptr) dtv[2]);
   }
-#elif SANITIZER_ANDROID || SANITIZER_NETBSD
+#elif SANITIZER_ANDROID
   *addr = 0;
   *size = 0;
 #else
 # error "Unknown OS"
 #endif
 }
 #endif
 

test/tsan/tls_race.cc

int main() {
   Var = 43;
   barrier_wait(&barrier);
   pthread_join(t, 0);
 }
 
 // CHECK: WARNING: ThreadSanitizer: data race
 // CHECK-Linux:   Location is TLS of main thread.
 // CHECK-FreeBSD:   Location is TLS of main thread.
+// CHECK-NetBSD:   Location is TLS of main thread.
 // CHECK-Darwin:   Location is heap block of size 4

test/tsan/tls_race2.cc

int main() {
   pthread_t t;
   pthread_create(&t, 0, Thread, 0);
   pthread_join(t, 0);
 }
 
 // CHECK: WARNING: ThreadSanitizer: data race
 // CHECK-Linux:   Location is TLS of thread T1.
 // CHECK-FreeBSD:   Location is TLS of thread T1.
+// CHECK-NetBSD:   Location is TLS of thread T1.
 // CHECK-Darwin:   Location is heap block of size 4