Re: [PATCH -rcu/kcsan 23/23] objtool, kcsan: Remove memory barrier instrumentation from noinstr

Peter Zijlstra
2021-10-05T14:37:36Z

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.