linux-kernel - Re: [PATCH 03/16] powerpc: Fix objtool unannotated intra-function call warnings

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Message-ID: <c429f624-a25b-fe80-56c8-01cb733c3909@linux.vnet.ibm.com>
Date:   Thu, 18 Aug 2022 16:25:27 +0530
From:   Sathvika Vasireddy <sv@...ux.vnet.ibm.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Sathvika Vasireddy <sv@...ux.ibm.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Cc:     "jpoimboe@...hat.com" <jpoimboe@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "aik@...abs.ru" <aik@...abs.ru>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "mbenes@...e.cz" <mbenes@...e.cz>,
        "npiggin@...il.com" <npiggin@...il.com>,
        "chenzhongjin@...wei.com" <chenzhongjin@...wei.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "naveen.n.rao@...ux.vnet.ibm.com" <naveen.n.rao@...ux.vnet.ibm.com>
Subject: Re: [PATCH 03/16] powerpc: Fix objtool unannotated intra-function
 call warnings


On 10/08/22 14:02, Christophe Leroy wrote:
>
> Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit :
>> objtool throws unannotated intra-function call warnings
>> in the following assembly files.
>>
>> arch/powerpc/kernel/vector.o: warning: objtool: .text+0x53c: unannotated intra-function call
>>
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x60: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x124: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5d4: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5dc: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xcb8: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xd0c: unannotated intra-function call
>> arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x1030: unannotated intra-function call
>>
>> arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x358: unannotated intra-function call
>> arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x728: unannotated intra-function call
>> arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4d94: unannotated intra-function call
>> arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4ec4: unannotated intra-function call
>>
>> arch/powerpc/kvm/book3s_hv_interrupts.o: warning: objtool: .text+0x6c: unannotated intra-function call
>> arch/powerpc/kernel/misc_64.o: warning: objtool: .text+0x64: unannotated intra-function call
>>
> Before explaining how you fix it, can you explain why we get it ?
Sure.

objtool does not add STT_NOTYPE symbols with size 0 to the rbtree, which 
is why find_call_destination()
function is not able to find the destination symbol for 'bl' 
instruction. For such symbols, objtool is throwing
unannotated intra-function call warnings in assembly files. Fix these 
warnings by adding
SYM_FUNC_START_LOCAL() and SYM_FUNC_END() annotations to those symbols 
to be able to set symbol
type to STT_FUNC and set size of these symbols accordingly.

I'll add this explanation to the commit message.

Thanks for reviewing.

- Sathvika