Re: [PATCH v2 08/28] x86, build: use objtool mcount

From: Kees Cook
Date: Thu Sep 03 2020 - 17:58:38 EST


On Thu, Sep 03, 2020 at 01:30:33PM -0700, Sami Tolvanen wrote:
> Select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION is selected to use
> objtool to generate __mcount_loc sections for dynamic ftrace with
> Clang and gcc <5.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>

Am I right to understand that this fixes mcount for Clang generally
(i.e. it's not _strictly_ related to LTO, though LTO depends on this
change)? And does this mean mcount was working for gcc < 5?

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

--
Kees Cook