[hwasan] Verify Android TLS slot at startup.

[eugenis]

Summary

Add a check that TLS_SLOT_TSAN / TLS_SLOT_SANITIZER, whichever
android_get_tls_slot is using, is not conflicting with
TLS_SLOT_DLERROR.

[rprichard]

Looks good to me.

compiler-rt/lib/hwasan/hwasan_linux.cc

295

Should there be a newline at the end of the error message?

[eugenis]

Added newline at the end of the error message.

compiler-rt/lib/hwasan/hwasan.h

 void HwasanTSDThreadInit();
 
 void HwasanOnDeadlySignal(int signo, void *info, void *context);
 
 void UpdateMemoryUsage();
 
 void AppendToErrorMessageBuffer(const char *buffer);
 
+void AndroidTestTlsSlot();
+
 }  // namespace __hwasan
 
 #define HWASAN_MALLOC_HOOK(ptr, size)       \
   do {                                    \
     if (&__sanitizer_malloc_hook) {       \
       __sanitizer_malloc_hook(ptr, size); \
     }                                     \
     RunMallocHooks(ptr, size);            \

compiler-rt/lib/hwasan/hwasan.cc

void __hwasan_init() {
   CacheBinaryName();
   InitializeFlags();
 
   // Install tool-specific callbacks in sanitizer_common.
   SetCheckFailedCallback(HWAsanCheckFailed);
 
   __sanitizer_set_report_path(common_flags()->log_path);
 
+  AndroidTestTlsSlot();
+
   DisableCoreDumperIfNecessary();
 
   __hwasan_shadow_init();
 
   InitThreads();
   hwasanThreadList().CreateCurrentThread();
 
   MadviseShadow();

compiler-rt/lib/hwasan/hwasan_linux.cc

 #include "hwasan.h"
 #include "hwasan_dynamic_shadow.h"
 #include "hwasan_interface_internal.h"
 #include "hwasan_mapping.h"
 #include "hwasan_report.h"
 #include "hwasan_thread.h"
 #include "hwasan_thread_list.h"
 
+#include <dlfcn.h>
 #include <elf.h>
 #include <link.h>
 #include <pthread.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/resource.h>
 #include <sys/time.h>
uptr *GetCurrentThreadLongPtr() {
   return (uptr *)get_android_tls_ptr();
 }
 #else
 uptr *GetCurrentThreadLongPtr() {
   return &__hwasan_tls;
 }
 #endif
 
+#if SANITIZER_ANDROID
+void AndroidTestTlsSlot() {
+  uptr kMagicValue = 0x010203040A0B0C0D;
+  *(uptr *)get_android_tls_ptr() = kMagicValue;
+  dlerror();
+  if (*(uptr *)get_android_tls_ptr() != kMagicValue) {
+    Printf(
+        "ERROR: Incompatible version of Android: TLS_SLOT_SANITIZER(6) is used "
+        "for dlerror().\n");
+    Die();
+  }
+}
+#else
+void AndroidTestTlsSlot() {}
+#endif
+
 Thread *GetCurrentThread() {
   auto *R = (StackAllocationsRingBuffer*)GetCurrentThreadLongPtr();
   return hwasanThreadList().GetThreadByBufferAddress((uptr)(R->Next()));
 }
 
 struct AccessInfo {
   uptr addr;
   uptr size;