[sanitizer_common] Drop remaining support for Android 5 or older

compiler-rt/lib/asan/asan_rtl.cpp

@@ -494,7 +494,6 @@ static bool AsanInitInternal() {
   AsanThread *main_thread = CreateMainThread();
   CHECK_EQ(0, main_thread->tid());
   force_interface_symbols();  // no-op.
-  SanitizerInitializeUnwinder();
 
   if (CAN_SANITIZE_LEAKS) {
     __lsan::InitCommonLsan();

compiler-rt/lib/memprof/memprof_rtl.cpp

@@ -219,7 +219,6 @@ static void MemprofInitInternal() {
   MemprofThread *main_thread = CreateMainThread();
   CHECK_EQ(0, main_thread->tid());
   force_interface_symbols(); // no-op.
-  SanitizerInitializeUnwinder();
 
   Symbolizer::LateInitialize();
 

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -925,12 +925,6 @@ class ListOfModules {
 // Callback type for iterating over a set of memory ranges.
 typedef void (*RangeIteratorCallback)(uptr begin, uptr end, void *arg);
 
-enum AndroidApiLevel {
-  ANDROID_NOT_ANDROID = 0,
-  ANDROID_LOLLIPOP_MR1 = 22,
-  ANDROID_POST_LOLLIPOP = 23
-};
-
 void WriteToSyslog(const char *buffer);
 
 #if defined(SANITIZER_WINDOWS) && defined(_MSC_VER) && !defined(__clang__)
@@ -963,19 +957,8 @@ inline void AndroidLogInit() {}
 inline void SetAbortMessage(const char *) {}
 #endif
 
-#if SANITIZER_ANDROID
-void SanitizerInitializeUnwinder();
-AndroidApiLevel AndroidGetApiLevel();
-#else
-inline void AndroidLogWrite(const char *buffer_unused) {}
-inline void SanitizerInitializeUnwinder() {}
-inline AndroidApiLevel AndroidGetApiLevel() { return ANDROID_NOT_ANDROID; }
-#endif
-
 inline uptr GetPthreadDestructorIterations() {
-#if SANITIZER_ANDROID
-  return (AndroidGetApiLevel() == ANDROID_LOLLIPOP_MR1) ? 8 : 4;
-#elif SANITIZER_POSIX
+#if SANITIZER_ANDROID || SANITIZER_POSIX
   return 4;
 #else
 // Unused on Windows.

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

@@ -1901,54 +1901,6 @@ int internal_uname(struct utsname *buf) {
 }
 #  endif
 
-#  if SANITIZER_ANDROID
-static int dl_iterate_phdr_test_cb(struct dl_phdr_info *info, size_t size,
-                                   void *data) {
-  // Any name starting with "lib" indicates a bug in L where library base names
-  // are returned instead of paths.
-  if (info->dlpi_name && info->dlpi_name[0] == 'l' &&
-      info->dlpi_name[1] == 'i' && info->dlpi_name[2] == 'b') {
-    *(bool *)data = true;
-    return 1;
-  }
-  return 0;
-}
-
-static atomic_uint32_t android_api_level;
-
-static AndroidApiLevel AndroidDetectApiLevelStatic() {
-#    if __ANDROID_API__ <= 22
-  return ANDROID_LOLLIPOP_MR1;
-#    else
-  return ANDROID_POST_LOLLIPOP;
-#    endif
-}
-
-static AndroidApiLevel AndroidDetectApiLevel() {
-  bool base_name_seen = false;
-  dl_iterate_phdr(dl_iterate_phdr_test_cb, &base_name_seen);
-  if (base_name_seen)
-    return ANDROID_LOLLIPOP_MR1;  // L MR1
-  return ANDROID_POST_LOLLIPOP;   // post-L
-  // Plain L (API level 21) is completely broken wrt ASan and not very
-  // interesting to detect.
-}
-
-extern "C" __attribute__((weak)) void *_DYNAMIC;
-
-AndroidApiLevel AndroidGetApiLevel() {
-  AndroidApiLevel level =
-      (AndroidApiLevel)atomic_load(&android_api_level, memory_order_relaxed);
-  if (level)
-    return level;
-  level = &_DYNAMIC == nullptr ? AndroidDetectApiLevelStatic()
-                               : AndroidDetectApiLevel();
-  atomic_store(&android_api_level, level, memory_order_relaxed);
-  return level;
-}
-
-#  endif
-
 static HandleSignalMode GetHandleSignalModeImpl(int signum) {
   switch (signum) {
     case SIGABRT:

compiler-rt/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cpp

@@ -91,38 +91,6 @@ _Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
 
 }  // namespace
 
-#if SANITIZER_ANDROID
-void SanitizerInitializeUnwinder() {
-  if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return;
-
-  // Pre-lollipop Android can not unwind through signal handler frames with
-  // libgcc unwinder, but it has a libcorkscrew.so library with the necessary
-  // workarounds.
-  void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
-  if (!p) {
-    VReport(1,
-            "Failed to open libcorkscrew.so. You may see broken stack traces "
-            "in SEGV reports.");
-    return;
-  }
-  acquire_my_map_info_list =
-      (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
-  release_my_map_info_list =
-      (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
-  unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
-      p, "unwind_backtrace_signal_arch");
-  if (!acquire_my_map_info_list || !release_my_map_info_list ||
-      !unwind_backtrace_signal_arch) {
-    VReport(1,
-            "Failed to find one of the required symbols in libcorkscrew.so. "
-            "You may see broken stack traces in SEGV reports.");
-    acquire_my_map_info_list = 0;
-    unwind_backtrace_signal_arch = 0;
-    release_my_map_info_list = 0;
-  }
-}
-#endif
-
 void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
   CHECK_GE(max_depth, 2);
   size = 0;