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Re: [committed, PATCH] Always create dynsym section with dynamic sections
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Faraz Shahbazker <faraz dot shahbazker at imgtec dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Sat, 23 Apr 2016 05:27:41 -0700
- Subject: Re: [committed, PATCH] Always create dynsym section with dynamic sections
- Authentication-results: sourceware.org; auth=none
- References: <20160223003208 dot GA30022 at intel dot com> <571A59A8 dot 4000700 at imgtec dot com> <CAMe9rOqr+E11vmpMV4Fo8Js_nCdsrcKpWKXQCUy+qSjjod=_hg at mail dot gmail dot com> <571A73BE dot 4000709 at imgtec dot com> <CAMe9rOp4nZHfL2=st5-fap84C7zOnnyjrU7e0_+QWe1jYhK6cw at mail dot gmail dot com> <DCB1C42372B1674B8F912A294CCB775A92D4E930 at BADAG02 dot ba dot imgtec dot org> <CAMe9rOpZECsq2U4Gb5CJw=y-vhmd_kDmTa0nZf+eqqTRUqDBKw at mail dot gmail dot com> <571AD1EE dot 1040005 at imgtec dot com> <CAMe9rOrcnGADH4w=-Zv8A7iXj9SjKzb5yGVcqeaLh60-tgjRtA at mail dot gmail dot com> <571ADE8F dot 9000000 at imgtec dot com>
On Fri, Apr 22, 2016 at 7:31 PM, Faraz Shahbazker
> On 04/22/16 19:05, H.J. Lu wrote:
>> On Fri, Apr 22, 2016 at 6:37 PM, Faraz Shahbazker
>> <firstname.lastname@example.org> wrote:
>>> On 04/22/16 16:24, H.J. Lu wrote:
>>>> On Fri, Apr 22, 2016 at 2:49 PM, Faraz Shahbazker
>>>> <Faraz.Shahbazker@imgtec.com> wrote:
>>>>> On 04/22/2016 12:28 PM, H.J. Lu wrote:
>>>>>> On Fri, Apr 22, 2016 at 11:55 AM, Faraz Shahbazker
>>>>>>> + if (dynsymcount != 0 || elf_hash_table (info)->dynamic_sections_created)
>>>>>>> + ++dynsymcount;
>>>>>> Are you saying dynamic_sections_created is 0 for MIPS here
>>>>>> and will become 1 later?
>>>>> No, it will remain 0. The link is static, but the hash_table is still used to
>>>>> record global symbols that have GOT relocations against them. Ofc, this
>>>>> hash_table does not result in creation of a dynsym section, because well,
>>>>> dynamic_sections_created is 0.
>>>>> Check the list of callers to bfd_elf_link_record_dynamic_symbol(), a number of
>>>>> architectures use the link_hash_table in situations where it is not clear whether it is
>>>>> being used to track dynamic symbols for a dynamic executable, as it is for x86.
>>>> So MIPS doesn't have dynamic symbols in this case. It just borrows
>>>> dynsymcount for different purpose. Is this correct?
>>> Not quite! MIPS is expecting dynsymcount to count the number of symbols
>>> that would have gone in to the .dynsym, even for a static executable. That way
>>> parts of the arch-specific code can remain agnostic to the static/dynamic nature
>>> of the link. It may not be used exactly as documented, but its not being used
>>> for what one would call a different purpose.
>>> All we need is for handling of dynsymcount when renumbering to be consistent with
>>> its initialization. If the initial increment for a NULL symbol was not gated by
>>> dynamic_sections_created, then the increment when renumbering should also not.
>>> If the increment when renumbering has to be gated by dynamic_sections_created,
>>> then the initial increment must also be so.
>> From what you are saying, shouldn't dynsymcount be incremented
> No. Always, when the table is non-empty + whatever else you need.
You said dynsym should be treated treated the same for static and
dynamic executables. dynsymcount is number of dynsym + 1 in
dynamic executable. Why isn't it true for static executable?