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Pull in r345002 from upstream lld trunk:

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Don't mess up RelIplt symbols during relocatable processing

  Summary:
  During upgrading of the FreeBSD source tree with lld 7.0.0, I noticed
  that it started complaining about crt1.o having an "index past the
  end of the symbol table".

  Such a symbol table looks approximately like this, viewed with
  readelf -s (note the Ndx field being messed up):

  Symbol table '.symtab' contains 4 entries:
     Num:    Value  Size Type    Bind   Vis      Ndx Name
       0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
       1: 00000000     0 SECTION LOCAL  DEFAULT    1
       2: 00000000     0 NOTYPE  WEAK   HIDDEN  RSV[0xffff] __rel_iplt_end
       3: 00000000     0 NOTYPE  WEAK   HIDDEN  RSV[0xffff] __rel_iplt_start

  At first, it seemed that recent ifunc relocation work had caused this:
  <https://reviews.freebsd.org/rS339351>, but it turned out that it was
  due to incorrect processing of the object files by lld, when using -r
  (a.k.a. --relocatable).

  Bisecting showed that rL324421 ("Convert a use of Config->Static") was
  the commit where this new behavior began.  Simply reverting it solved
  the issue, and the __rel_iplt symbols had an index of UND again.

  Looking at Rafael's commit message, I think he simply missed the
  possibility of --relocatable being in effect, so I have added an
  additional check for it.

  I also added a simple regression test case.

  Reviewers: grimar, ruiu, emaste, espindola

  Reviewed By: ruiu

  Subscribers: arichardson, krytarowski, llvm-commits

  Differential Revision: https://reviews.llvm.org/D53515

This fixes a problem in lld where it places incorrect indexes for ifunc
related symbols in crt1.o and friends, making it impossible to link most
normal programs with it.
This commit is contained in:
Dimitry Andric 2018-10-23 20:56:59 +00:00
parent f3e1dfebeb
commit 950f620367
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/clang700-import/; revision=339669
1 changed files with 1 additions and 1 deletions
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2
contrib/llvm/tools/lld/ELF/Writer.cpp
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@ -874,7 +874,7 @@ void PhdrEntry::add(OutputSection *Sec) {
// need these symbols, since IRELATIVE relocs are resolved through GOT
// and PLT. For details, see http://www.airs.com/blog/archives/403.
template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {
if (needsInterpSection())
if (Config->Relocatable || needsInterpSection())
return;
StringRef S = Config->IsRela ? "__rela_iplt_start" : "__rel_iplt_start";
addOptionalRegular(S, InX::RelaIplt, 0, STV_HIDDEN, STB_WEAK);