On Tue, Oct 05, 2021 at 12:59:05PM +0200, Marco Elver wrote:

Teach objtool to turn instrumentation required for memory barrier
modeling into nops in noinstr text.

The __tsan_func_entry/exit calls are still emitted by compilers even
with the __no_sanitize_thread attribute. The memory barrier
instrumentation will be inserted explicitly (without compiler help), and
thus needs to also explicitly be removed.

How is arm64 and others using kernel/entry + noinstr going to fix this?

ISTR they fully rely on the compilers not emitting instrumentation,
since they don't have objtool to fix up stray issues like this.