[scudo] Disable memory tagging on arm64_32

[ddcc]

Summary

arm64_32 is an ILP32 platform

[eugenis]

LGTM, but would it be more idiomatic to check for the _ILP32 macro?

[ddcc]

Use ILP32 macro

[eugenis]

Mild preference for !defined(__ILP32__).
LGTM

compiler-rt/lib/scudo/standalone/memtag.h

 
 #if SCUDO_LINUX
 #include <sys/auxv.h>
 #include <sys/prctl.h>
 #endif
 
 namespace scudo {
 
-#if (__clang_major__ >= 12 && defined(__aarch64__)) || defined(SCUDO_FUZZ)
+#if (__clang_major__ >= 12 && defined(__aarch64__) &&                          \
+     __SIZEOF_POINTER__ == 8) ||                                               \
+    defined(SCUDO_FUZZ)
 
 // We assume that Top-Byte Ignore is enabled if the architecture supports memory
 // tagging. Not all operating systems enable TBI, so we only claim architectural
 // support for memory tagging if the operating system enables TBI.
 // HWASan uses the top byte for its own purpose and Scudo should not touch it.
 #if SCUDO_LINUX && !defined(SCUDO_DISABLE_TBI) &&                              \
     !__has_feature(hwaddress_sanitizer)
 inline constexpr bool archSupportsMemoryTagging() { return true; }

 
 inline NORETURN uint8_t extractTag(uptr Ptr) {
   (void)Ptr;
   UNREACHABLE("memory tagging not supported");
 }
 
 #endif
 
-#if __clang_major__ >= 12 && defined(__aarch64__)
+#if __clang_major__ >= 12 && defined(__aarch64__) && __SIZEOF_POINTER__ == 8
 
 #if SCUDO_LINUX
 
 inline bool systemSupportsMemoryTagging() {
 #ifndef HWCAP2_MTE
 #define HWCAP2_MTE (1 << 18)
 #endif
   return getauxval(AT_HWCAP2) & HWCAP2_MTE;