Le 16/06/2022 à 15:34, Naveen N. Rao a écrit :
> Christophe Leroy wrote:
>>
>>
>> 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-chenzhong...@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;
>
> How does 'sizeof(u64)' work here?
>
sizeof(u64) is always 8 by definition.
So if size is 8 we are working on a binary file for a 64 bits target, if
not it means we are working for a 32 bits target.
Christophe
