1 files changed, 154 insertions, 0 deletions
diff --git a/lib/sanitizer_common/sanitizer_tls_get_addr.cpp b/lib/sanitizer_common/sanitizer_tls_get_addr.cpp
new file mode 100644
index 000000000000..9ca898a306a8
--- /dev/null
+++ b/lib/sanitizer_common/sanitizer_tls_get_addr.cpp
@@ -0,0 +1,154 @@
+//===-- sanitizer_tls_get_addr.cpp ----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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
+__attribute__((tls_model("initial-exec")))
+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_Deallocate(DTLS::DTV *dtv, uptr size) {
+  if (!size) return;
+  VReport(2, "__tls_get_addr: DTLS_Deallocate %p %zd\n", dtv, size);
+  UnmapOrDie(dtv, size * sizeof(DTLS::DTV));
+  atomic_fetch_sub(&number_of_live_dtls, 1, memory_order_relaxed);
+}
+
+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");
+  uptr num_live_dtls =
+      atomic_fetch_add(&number_of_live_dtls, 1, memory_order_relaxed);
+  VReport(2, "__tls_get_addr: DTLS_Resize %p %zd\n", &dtls, num_live_dtls);
+  CHECK_LT(num_live_dtls, 1 << 20);
+  uptr old_dtv_size = dtls.dtv_size;
+  DTLS::DTV *old_dtv = dtls.dtv;
+  if (old_dtv_size)
+    internal_memcpy(new_dtv, dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
+  dtls.dtv = new_dtv;
+  dtls.dtv_size = new_size;
+  if (old_dtv_size)
+    DTLS_Deallocate(old_dtv, old_dtv_size);
+}
+
+void DTLS_Destroy() {
+  if (!common_flags()->intercept_tls_get_addr) return;
+  VReport(2, "__tls_get_addr: DTLS_Destroy %p %zd\n", &dtls, dtls.dtv_size);
+  uptr s = dtls.dtv_size;
+  dtls.dtv_size = kDestroyedThread;  // Do this before unmap for AS-safety.
+  DTLS_Deallocate(dtls.dtv, s);
+}
+
+#if defined(__powerpc64__) || defined(__mips__)
+// This is glibc's TLS_DTV_OFFSET:
+// "Dynamic thread vector pointers point 0x8000 past the start of each
+//  TLS block."
+static const uptr kDtvOffset = 0x8000;
+#else
+static const uptr kDtvOffset = 0;
+#endif
+
+DTLS::DTV *DTLS_on_tls_get_addr(void *arg_void, void *res,
+                                uptr static_tls_begin, uptr static_tls_end) {
+  if (!common_flags()->intercept_tls_get_addr) return 0;
+  TlsGetAddrParam *arg = reinterpret_cast<TlsGetAddrParam *>(arg_void);
+  uptr dso_id = arg->dso_id;
+  if (dtls.dtv_size == kDestroyedThread) return 0;
+  DTLS_Resize(dso_id + 1);
+  if (dtls.dtv[dso_id].beg) return 0;
+  uptr tls_size = 0;
+  uptr tls_beg = reinterpret_cast<uptr>(res) - arg->offset - kDtvOffset;
+  VReport(2, "__tls_get_addr: %p {%p,%p} => %p; tls_beg: %p; sp: %p "
+             "num_live_dtls %zd\n",
+          arg, arg->dso_id, arg->offset, res, tls_beg, &tls_beg,
+          atomic_load(&number_of_live_dtls, memory_order_relaxed));
+  if (dtls.last_memalign_ptr == tls_beg) {
+    tls_size = dtls.last_memalign_size;
+    VReport(2, "__tls_get_addr: glibc <=2.18 suspected; tls={%p,%p}\n",
+        tls_beg, tls_size);
+  } else if (tls_beg >= static_tls_begin && tls_beg < static_tls_end) {
+    // This is the static TLS block which was initialized / unpoisoned at thread
+    // creation.
+    VReport(2, "__tls_get_addr: static tls: %p\n", tls_beg);
+    tls_size = 0;
+  } 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;
+    VReport(2, "__tls_get_addr: glibc >=2.19 suspected; tls={%p %p}\n",
+        tls_beg, tls_size);
+  } else {
+    VReport(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;
+  return dtls.dtv + dso_id;
+}
+
+void DTLS_on_libc_memalign(void *ptr, uptr size) {
+  if (!common_flags()->intercept_tls_get_addr) return;
+  VReport(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; }
+
+bool DTLSInDestruction(DTLS *dtls) {
+  return dtls->dtv_size == kDestroyedThread;
+}
+
+#else
+void DTLS_on_libc_memalign(void *ptr, uptr size) {}
+DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res,
+  unsigned long, unsigned long) { return 0; }
+DTLS *DTLS_Get() { return 0; }
+void DTLS_Destroy() {}
+bool DTLSInDestruction(DTLS *dtls) {
+  UNREACHABLE("dtls is unsupported on this platform!");
+}
+
+#endif  // SANITIZER_INTERCEPT_TLS_GET_ADDR
+
+}  // namespace __sanitizer