From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Sathvika Vasireddy <sv@linux.vnet.ibm.com>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"aik@ozlabs.ru" <aik@ozlabs.ru>,
Sathvika Vasireddy <sv@linux.ibm.com>,
"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
"naveen.n.rao@linux.vnet.ibm.com"
<naveen.n.rao@linux.vnet.ibm.com>,
"mbenes@suse.cz" <mbenes@suse.cz>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Chen Zhongjin <chenzhongjin@huawei.com>
Subject: Re: [RFC PATCH 4/4] objtool/powerpc: Add --mcount specific implementation
Date: Tue, 31 May 2022 08:20:41 +0200 [thread overview]
Message-ID: <c1e2cf35-2a8d-87e6-3a7e-7f144392db23@csgroup.eu> (raw)
In-Reply-To: <f1decbb7-b441-a241-469a-4ba118e08212@csgroup.eu>
Le 25/05/2022 à 19:27, Christophe Leroy a écrit :
>
>
> Le 24/05/2022 à 15:33, Christophe Leroy a écrit :
>>
>>
>> Le 24/05/2022 à 13:00, Sathvika Vasireddy a écrit :
>>>>
>>>>> +{
>>>>> + switch (elf->ehdr.e_machine) {
>>>>> + case EM_X86_64:
>>>>> + return R_X86_64_64;
>>>>> + case EM_PPC64:
>>>>> + return R_PPC64_ADDR64;
>>>>> + default:
>>>>> + WARN("unknown machine...");
>>>>> + exit(-1);
>>>>> + }
>>>>> +}
>>>> Wouldn't it be better to make that function arch specific ?
>>>
>>> This is so that we can support cross architecture builds.
>>>
>>
>>
>> I'm not sure I follow you here.
>>
>> This is only based on the target, it doesn't depend on the build host so
>> I can't the link with cross arch builds.
>>
>> The same as you have arch_decode_instruction(), you could have
>> arch_elf_reloc_type_long()
>> It would make sense indeed, because there is no point in supporting X86
>> relocation when you don't support X86 instruction decoding.
>>
>
> Could simply be some macro defined in
> tools/objtool/arch/powerpc/include/arch/elf.h and
> tools/objtool/arch/x86/include/arch/elf.h
>
> The x86 version would be:
>
> #define R_ADDR(elf) R_X86_64_64
>
> And the powerpc version would be:
>
> #define R_ADDR(elf) (elf->ehdr.e_machine == EM_PPC64 ? R_PPC64_ADDR64 :
> R_PPC_ADDR32)
>
Well, looking once more, and taking into account the patch from Chen
https://lore.kernel.org/lkml/20220531020744.236970-4-chenzhongjin@huawei.com/
It would be easier to just define two macros:
#define R_ABS64 R_PPC64_ADDR64
#define R_ABS32 R_PPC_ADDR32
And then in the caller, as we know the size, do something like
size == sizeof(u64) ? R_ABS64 : R_ABS32;
Christophe
next prev parent reply other threads:[~2022-05-31 6:20 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 17:55 [RFC PATCH 0/4] objtool: Enable and implement --mcount option on powerpc Sathvika Vasireddy
2022-05-23 17:55 ` [RFC PATCH 1/4] objtool: Add --mnop as an option to --mcount Sathvika Vasireddy
2022-05-24 8:54 ` Christophe Leroy
2022-05-24 10:15 ` Naveen N. Rao
2022-05-24 10:20 ` Christophe Leroy
2022-05-24 10:31 ` Naveen N. Rao
2022-05-25 11:36 ` Peter Zijlstra
2022-05-26 11:51 ` Naveen N. Rao
2022-05-23 17:55 ` [RFC PATCH 2/4] objtool: Enable objtool to run only on files with ftrace enabled Sathvika Vasireddy
2022-05-24 8:57 ` Christophe Leroy
2022-05-24 10:53 ` Sathvika Vasireddy
2022-05-24 13:28 ` Christophe Leroy
2022-05-23 17:55 ` [RFC PATCH 3/4] objtool/powerpc: Enable objtool to be built on ppc Sathvika Vasireddy
2022-05-24 9:13 ` Christophe Leroy
2022-05-23 17:55 ` [RFC PATCH 4/4] objtool/powerpc: Add --mcount specific implementation Sathvika Vasireddy
2022-05-24 9:35 ` Christophe Leroy
2022-05-24 11:00 ` Sathvika Vasireddy
2022-05-24 13:33 ` Christophe Leroy
2022-05-25 17:27 ` Christophe Leroy
2022-05-31 6:20 ` Christophe Leroy [this message]
2022-06-16 13:34 ` Naveen N. Rao
2022-06-16 13:40 ` Christophe Leroy
2022-06-16 13:57 ` Peter Zijlstra
2022-06-16 14:06 ` Christophe Leroy
2022-06-17 14:04 ` Naveen N. Rao
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