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<body><span class="vcard"><a class="email" href="mailto:rafael@espindo.la" title="Rafael Ávila de Espíndola <rafael@espindo.la>"> <span class="fn">Rafael Ávila de Espíndola</span></a>
</span> changed
<a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - _GLOBAL_OFFSET_TABLE_ does not point to the beginning of .got.plt"
href="https://bugs.llvm.org/show_bug.cgi?id=36555">bug 36555</a>
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<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>WONTFIX
</td>
<td>---
</td>
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<td style="text-align:right;">Status</td>
<td>RESOLVED
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<td>REOPENED
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<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - _GLOBAL_OFFSET_TABLE_ does not point to the beginning of .got.plt"
href="https://bugs.llvm.org/show_bug.cgi?id=36555#c9">Comment # 9</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - _GLOBAL_OFFSET_TABLE_ does not point to the beginning of .got.plt"
href="https://bugs.llvm.org/show_bug.cgi?id=36555">bug 36555</a>
from <span class="vcard"><a class="email" href="mailto:rafael@espindo.la" title="Rafael Ávila de Espíndola <rafael@espindo.la>"> <span class="fn">Rafael Ávila de Espíndola</span></a>
</span></b>
<pre>(In reply to Rafael Ávila de Espíndola from <a href="show_bug.cgi?id=36555#c8">comment #8</a>)
<span class="quote">> > With this in mind I think our best course of action is:
> > - Extend writeGotPltHeader() to more targets.
> > - Either adjust the default section sorting to make sure .got.plt follows
> > .got or change _GLOBAL_OFFSET_TABLE_ to the start of the .got.plt.
>
> Interesting. This would mean flipping relro to the start of the RW program
> header since .got is RELRO and .got.plt is not.
>
> I will dig at the history a bit to see why we have the current order.</span >
Found it.
The reason is that we need to have a single RelRO area covering nobits and non
nobits sections. Since bss has to go at the end, so has RelRo:
// We place nobits RelRo sections before plain r/w ones, and non-nobits RelRo
// sections after r/w ones, so that the RelRo sections are contiguous.
bool IsRelRo = isRelroSection(Sec);
if (IsNonTlsNoBits && !IsRelRo)
Rank |= RF_NON_TLS_BSS_RO;
if (!IsNonTlsNoBits && IsRelRo)
Rank |= RF_NON_TLS_BSS_RO;
My understanding is that gnu linker just never use a RelRO nobits sections.
It seems we have to make the section _GLOBAL_OFFSET_TABLE_ points to
architecture dependent or change glibc (not sure how realistic that is).</pre>
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