linux-kernel - Re: [RFC PATCH v1 2/3] powerpc: Mark all .S files invalid for objtool

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Date:   Tue, 20 Jun 2023 06:15:54 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Naveen N Rao <naveen@...nel.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Sathvika Vasireddy <sv@...ux.ibm.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [RFC PATCH v1 2/3] powerpc: Mark all .S files invalid for objtool



Le 20/06/2023 à 08:04, Naveen N Rao a écrit :
> Christophe Leroy wrote:
>> A lot of work is required in .S files in order to get them ready
>> for objtool checks.
>>
>> For the time being, exclude them from the checks.
>>
>> This is done with the script below:
>>
>>     #!/bin/sh
>>     DIRS=`find arch/powerpc -name "*.S" -exec dirname {} \; | sort | 
>> uniq`
>>     for d in $DIRS
>>     do
>>         pushd $d
>>         echo >> Makefile
>>         for f in *.S
>>         do
>>             echo "OBJECT_FILES_NON_STANDARD_$f := y" | sed s/"\.S"/".o"/g
>>         done >> Makefile
>>         popd
>>     done
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
>> ---
>>  arch/powerpc/boot/Makefile                 | 17 +++++++++
>>  arch/powerpc/crypto/Makefile               | 13 +++++++
>>  arch/powerpc/kernel/Makefile               | 44 ++++++++++++++++++++++
>>  arch/powerpc/kernel/trace/Makefile         |  4 ++
>>  arch/powerpc/kernel/vdso/Makefile          | 11 ++++++
>>  arch/powerpc/kexec/Makefile                |  2 +
>>  arch/powerpc/kvm/Makefile                  | 13 +++++++
>>  arch/powerpc/lib/Makefile                  | 25 ++++++++++++
>>  arch/powerpc/mm/book3s32/Makefile          |  3 ++
>>  arch/powerpc/mm/nohash/Makefile            |  3 ++
>>  arch/powerpc/perf/Makefile                 |  2 +
>>  arch/powerpc/platforms/44x/Makefile        |  2 +
>>  arch/powerpc/platforms/52xx/Makefile       |  3 ++
>>  arch/powerpc/platforms/83xx/Makefile       |  2 +
>>  arch/powerpc/platforms/cell/spufs/Makefile |  3 ++
>>  arch/powerpc/platforms/pasemi/Makefile     |  2 +
>>  arch/powerpc/platforms/powermac/Makefile   |  3 ++
>>  arch/powerpc/platforms/powernv/Makefile    |  3 ++
>>  arch/powerpc/platforms/ps3/Makefile        |  2 +
>>  arch/powerpc/platforms/pseries/Makefile    |  2 +
>>  arch/powerpc/purgatory/Makefile            |  3 ++
>>  arch/powerpc/sysdev/Makefile               |  3 ++
>>  arch/powerpc/xmon/Makefile                 |  3 ++
>>  23 files changed, 168 insertions(+)
>>
> 
> I think it might be better to have a config option so that architectures 
> can opt-in to skip objtool on asm files. We can then do:

Well, the idea here was to initially opt out every file in order to 
quickly add support for objtool uaccess checking, and then opt-in back 
files one by one once they are ready for it.

In most files,all we have to do is to replace all _GLOBAL() by 
SYM_FUNC_START(), add a SYM_FUNC_END() at the end of the function, then 
do the same with SYM_FUNC_START_LOCAL() with all non global functions.

That's easy to do and worth it but it takes time, hence the idea of an 
incremental approach.

Christophe