1 files changed, 114 insertions, 0 deletions
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_tls_get_addr.cc b/compiler-rt/lib/sanitizer_common/sanitizer_tls_get_addr.cc
new file mode 100644
index 00000000000..7d4663d5f08
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_tls_get_addr.cc
@@ -0,0 +1,114 @@
+//===-- sanitizer_tls_get_addr.cc -----------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Handle the __tls_get_addr call.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_tls_get_addr.h"
+
+#include "sanitizer_flags.h"
+#include "sanitizer_platform_interceptors.h"
+
+namespace __sanitizer {
+#if SANITIZER_INTERCEPT_TLS_GET_ADDR
+
+// The actual parameter that comes to __tls_get_addr
+// is a pointer to a struct with two words in it:
+struct TlsGetAddrParam {
+  uptr dso_id;
+  uptr offset;
+};
+
+// Glibc starting from 2.19 allocates tls using __signal_safe_memalign,
+// which has such header.
+struct Glibc_2_19_tls_header {
+  uptr size;
+  uptr start;
+};
+
+// This must be static TLS, i.e. the run-time should be build with
+// -ftls-model=initial-exec or equivalent.
+static __thread DTLS dtls;
+
+// Make sure we properly destroy the DTLS objects:
+// this counter should never get too large.
+static atomic_uintptr_t number_of_live_dtls;
+
+static const uptr kDestroyedThread = -1;
+
+static inline void DTLS_Resize(uptr new_size) {
+  if (dtls.dtv_size >= new_size) return;
+  new_size = RoundUpToPowerOfTwo(new_size);
+  new_size = Max(new_size, 4096UL / sizeof(DTLS::DTV));
+  DTLS::DTV *new_dtv =
+      (DTLS::DTV *)MmapOrDie(new_size * sizeof(DTLS::DTV), "DTLS_Resize");
+  CHECK_LT(atomic_fetch_add(&number_of_live_dtls, 1, memory_order_relaxed),
+           1 << 20);
+  if (dtls.dtv_size)
+    internal_memcpy(new_dtv, dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
+  DTLS_Destroy();
+  dtls.dtv = new_dtv;
+  dtls.dtv_size = new_size;
+}
+
+void DTLS_Destroy() {
+  if (!dtls.dtv_size) return;
+  UnmapOrDie(dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
+  atomic_fetch_sub(&number_of_live_dtls, 1, memory_order_relaxed);
+  dtls.dtv_size = kDestroyedThread;
+}
+
+void DTLS_on_tls_get_addr(void *arg_void, void *res) {
+  TlsGetAddrParam *arg = reinterpret_cast<TlsGetAddrParam *>(arg_void);
+  uptr dso_id = arg->dso_id;
+  if (dtls.dtv_size == kDestroyedThread) return;
+  DTLS_Resize(dso_id + 1);
+  if (dtls.dtv[dso_id].beg)
+    return;
+  uptr tls_size = 0;
+  uptr tls_beg = reinterpret_cast<uptr>(res) - arg->offset;
+  VPrintf(2, "__tls_get_addr: %p {%p,%p} => %p; tls_beg: %p\n", arg,
+          arg->dso_id, arg->offset, res, tls_beg);
+  if (dtls.last_memalign_ptr == tls_beg) {
+    tls_size = dtls.last_memalign_size;
+    VPrintf(2, "__tls_get_addr: glibc <=2.18 suspected; tls={%p,%p}\n", tls_beg,
+            tls_size);
+  } else if ((tls_beg % 4096) == sizeof(Glibc_2_19_tls_header)) {
+    // We may want to check gnu_get_libc_version().
+    Glibc_2_19_tls_header *header = (Glibc_2_19_tls_header *)tls_beg - 1;
+    tls_size = header->size;
+    tls_beg = header->start;
+    VPrintf(2, "__tls_get_addr: glibc >=2.19 suspected; tls={%p %p}\n", tls_beg,
+            tls_size);
+  } else {
+    VPrintf(2, "__tls_get_addr: Can't guess glibc version\n");
+    // This may happen inside the DTOR of main thread, so just ignore it.
+    tls_size = 0;
+  }
+  dtls.dtv[dso_id].beg = tls_beg;
+  dtls.dtv[dso_id].size = tls_size;
+}
+
+void DTLS_on_libc_memalign(void *ptr, uptr size) {
+  VPrintf(2, "DTLS_on_libc_memalign: %p %p\n", ptr, size);
+  dtls.last_memalign_ptr = reinterpret_cast<uptr>(ptr);
+  dtls.last_memalign_size = size;
+}
+
+DTLS *DTLS_Get() { return &dtls; }
+
+#else
+void DTLS_on_libc_memalign(void *ptr, uptr size) {}
+void DTLS_on_tls_get_addr(void *arg, void *res) {}
+DTLS *DTLS_Get() { return 0; }
+void DTLS_Destroy() {}
+#endif  // SANITIZER_INTERCEPT_TLS_GET_ADDR
+
+}  // namespace __sanitizer