[compiler-rt][hwasan] Check address tagging mode in InitializeOsSupport on Fuchsia

[phosek]

compiler-rt/lib/hwasan/hwasan_fuchsia.cpp

193

The failed check is going to print the result of the comparison followed by a stack trace which isn't particularly user friendly.

I'd consider printing a more self-explanatory message followed by a call to Die() similarly to how it's done on Linux: https://github.com/llvm/llvm-project/blob/d48479791f63d96cf9d0abff56ceba0cace77623/compiler-rt/lib/hwasan/hwasan_linux.cpp#L133

[phosek]

LGTM

[mcgrathr]

compiler-rt/lib/hwasan/hwasan_fuchsia.cpp

193

This is a bitmask to which new bits may be added in the future without changing this API.
So this should test with !(features & ZX_ARM64_...).

[leonardchan]

compiler-rt/lib/hwasan/hwasan_fuchsia.cpp

193

Fixed in D129318

compiler-rt/lib/hwasan/hwasan_fuchsia.cpp

 /// This file is a part of HWAddressSanitizer and contains Fuchsia-specific
 /// code.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_common/sanitizer_fuchsia.h"
 #if SANITIZER_FUCHSIA
 
+#include <zircon/features.h>
+#include <zircon/syscalls.h>
+
 #include "hwasan.h"
 #include "hwasan_interface_internal.h"
 #include "hwasan_report.h"
 #include "hwasan_thread.h"
 #include "hwasan_thread_list.h"
 
 // This TLS variable contains the location of the stack ring buffer and can be
 // used to always find the hwasan thread object associated with the current

 
 // On linux, this just would call `atexit(HwasanAtExit)`. The functions in
 // HwasanAtExit are unimplemented for Fuchsia and effectively no-ops, so this
 // function is unneeded.
 void InstallAtExitHandler() {}
 
 void HwasanInstallAtForkHandler() {}
 
-// TODO(fxbug.dev/81499): Once we finalize the tagged pointer ABI in zircon, we should come back
-// here and implement the appropriate check that TBI is enabled.
-void InitializeOsSupport() {}
+void InitializeOsSupport() {
+#ifdef __aarch64__
+  uint32_t features = 0;
+  CHECK_EQ(zx_system_get_features(ZX_FEATURE_KIND_ADDRESS_TAGGING, &features),
+           ZX_OK);
+  if (features != ZX_ARM64_FEATURE_ADDRESS_TAGGING_TBI &&
+      flags()->fail_without_syscall_abi) {
+    Printf(
+        "FATAL: HWAddressSanitizer requires a kernel with tagged address "
+        "ABI.\n");
+    Die();
+  }
+#endif
+}
 
 }  // namespace __hwasan
 
 extern "C" {
 
 void *__sanitizer_before_thread_create_hook(thrd_t thread, bool detached,
                                             const char *name, void *stack_base,
                                             size_t stack_size) {