[RFC PATCH v2 5/7] objtool: Enable objtool to run only on files with ftrace enabled

[Peter Zijlstra]

On Tue, May 24, 2022 at 03:17:45PM +0200, Christophe Leroy wrote:
> From: Sathvika Vasireddy <sv at linux.ibm.com>
> 
> This patch makes sure objtool runs only on the object files
> that have ftrace enabled, instead of running on all the object
> files.
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> Signed-off-by: Sathvika Vasireddy <sv at linux.ibm.com>
> Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
> ---
>  scripts/Makefile.build | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 2e0c3f9c1459..06ceffd92921 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -258,8 +258,8 @@ else
>  # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
>  # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
>  
> -$(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \
> -	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
> +$(obj)/%.o: objtool-enabled = $(and $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y),        \
> +        $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),y),y)

I think this breaks x86, quite a bit of files have ftrace disabled but
very much must run objtool anyway.