[PATCH] Always define referenced __start_SECNAME/__stop_SECNAME

[H.J. Lu]

On Wed, Jun 14, 2017 at 8:30 PM, Alan Modra <amodra@gmail.com> wrote:
> On Wed, Jun 14, 2017 at 06:20:47AM -0700, H.J. Lu wrote:
>> On Tue, Jun 13, 2017 at 8:50 PM, Alan Modra <amodra@gmail.com> wrote:
>> > I see these fails.  Please investigate and fix.  The powerpc-linux
>>
>> Most of tests are supported on targets without --gc-sections support or
>> with a leading underscore in symbol name.  I checked in a couple patches
>> to address them.
>>
>> > fails are due to leaving the __start and __stop symbols undefined when
>> > sizing dynamic sections, which is wrong.  That at least needs to be
>>
>> There is no need to discard relocs on undefined symbols with
>> non-default visibilty, which may be defined later like __start_SECNAME
>> and __stop_SECNAME, or are real errors.  I am enclosing a patch here.
>
> No, it is quite reasonable to discard these relocations, and it is a
> maintenance nightmare when symbols change state between
> allocate_dynrelocs and relocate_section.  Granted, that already
> happened for .startof. and .sizeof. symbols, but the existence of

It is normal for linker defined symbols to change state.  BFD just
has to deal with it.

> those special symbols was an undocumented feature of gas and ld.
> Making that happen for __start and __stop too just makes the problem
> worse.

The main difference is that __start_SECNAME and __stop_SECNAME
are marked as hidden.   Here is a patch to check it.

> In future please state on the mailing list which targets you tested
> against when posting global changes.  I assumed you had tested this
> change against a representative set of targets, but it's clear you
> didn't.
>

Sure.  I also have a request for you.   Please add a testcase when
you fix a global bug in the future, especially there is one in the bug
report.   It will prevent your bug fix from being accidentally bypassed later.

Thanks.

-- 
H.J.
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