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Date:   Thu, 1 Sep 2022 21:17:57 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Sathvika Vasireddy <sv@linux.ibm.com>
Cc:     linuxppc-dev@lists.ozlabs.org, jpoimboe@redhat.com,
        linux-kernel@vger.kernel.org, aik@ozlabs.ru, mpe@ellerman.id.au,
        mingo@redhat.com, christophe.leroy@csgroup.eu, rostedt@goodmis.org,
        mbenes@suse.cz, npiggin@gmail.com, chenzhongjin@huawei.com,
        naveen.n.rao@linux.vnet.ibm.com
Subject: Re: [PATCH v2 05/16] powerpc: Skip objtool from running on
 drivers/crypto/vmx/aesp8-ppc.o
Message-ID: <YxEFZXCnCH7F8yku@hirez.programming.kicks-ass.net>
References: <20220829055223.24767-1-sv@linux.ibm.com>
 <20220829055223.24767-6-sv@linux.ibm.com>
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On Mon, Aug 29, 2022 at 11:22:12AM +0530, Sathvika Vasireddy wrote:
> With objtool enabled, below warnings are seen when trying to build:
> 
> drivers/crypto/vmx/aesp8-ppc.o: warning: objtool: aes_p8_set_encrypt_key+0x44: unannotated intra-function call
> 
> drivers/crypto/vmx/aesp8-ppc.o: warning: objtool: .text+0x2448: unannotated intra-function call
> 
> drivers/crypto/vmx/aesp8-ppc.o: warning: objtool: .text+0x2d68: unannotated intra-function call
> 
> Skip objtool from running on this file, for two main reasons:
> 
> Since this file comes from OpenSSL, and since it is a perl file
> which generates a .S file, it may not be the best choice to
> make too many code changes to such files, unless absolutely
> necessary.
> 
> Second reason is that, at least as far as the objtool --mcount
> functionality is concerned, we do not have to run objtool on
> that file because that file does not have any calls to _mcount.
> 
> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
> ---
>  drivers/crypto/vmx/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/crypto/vmx/Makefile b/drivers/crypto/vmx/Makefile
> index 2560cfea1dec..7b41f0da6807 100644
> --- a/drivers/crypto/vmx/Makefile
> +++ b/drivers/crypto/vmx/Makefile
> @@ -9,3 +9,5 @@ targets += aesp8-ppc.S ghashp8-ppc.S
>  
>  $(obj)/aesp8-ppc.S $(obj)/ghashp8-ppc.S: $(obj)/%.S: $(src)/%.pl FORCE
>  	$(call if_changed,perl)
> +
> +OBJECT_FILES_NON_STANDARD_aesp8-ppc.o := y

Just be aware that the moment you start to run objtool on vmlinux.o this
annotation becomes unstuck.

Specifically things like LTO builds require this because there simply
isn't an object file before that.