[PATCH] D98732: scudo: Allow TBI to be disabled on Linux with a macro.

[Peter Collingbourne via Phabricator via llvm-commits]

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Android's native bridge (i.e. AArch64 emulator) doesn't support TBI so
we need a way to disable TBI on Linux when targeting the native bridge.

This can also be used to test the no-TBI code path on Linux (currently
only used on Fuchsia), or make Scudo compatible with very old
(pre-commit d50240a5f6ceaf690a77b0fccb17be51cfa151c2 from June 2013)
Linux kernels that do not enable TBI.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D98732

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


Index: compiler-rt/lib/scudo/standalone/memtag.h
===================================================================
--- compiler-rt/lib/scudo/standalone/memtag.h
+++ compiler-rt/lib/scudo/standalone/memtag.h
@@ -26,7 +26,7 @@
 // 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.
-#if SCUDO_LINUX
+#if SCUDO_LINUX && !defined(SCUDO_DISABLE_TBI)
 inline constexpr bool archSupportsMemoryTagging() { return true; }
 #else
 inline constexpr bool archSupportsMemoryTagging() { return false; }


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