Re: [RFC PATCH 2/4] objtool: Enable objtool to run only on files with ftrace enabled

From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Sathvika Vasireddy <sv@linux.ibm.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"mbenes@suse.cz" <mbenes@suse.cz>,
	"aik@ozlabs.ru" <aik@ozlabs.ru>,
	"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"naveen.n.rao@linux.vnet.ibm.com"
	<naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH 2/4] objtool: Enable objtool to run only on files with ftrace enabled
Date: Tue, 24 May 2022 08:57:55 +0000	[thread overview]
Message-ID: <89012c4c-e989-6092-d4f1-0dc4eca983f1@csgroup.eu> (raw)
In-Reply-To: <20220523175548.922671-3-sv@linux.ibm.com>

Le 23/05/2022 à 19:55, Sathvika Vasireddy a écrit :
> This patch makes sure objtool runs only on the object files
> that have ftrace enabled, instead of running on all the object
> files.

Why do that ?

What about static_calls ? There may be files without ftrace but with 
static calls.

By the way, it would be nice if we could use it only on C files.
I get the following errors for ASM files:

arch/powerpc/kernel/entry_32.o: warning: objtool: .text+0x1b4: 
unannotated intra-function call

> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
> ---
>   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)
>   
>   endif
>   