tree 74381721cd3fc28c47dc4173a48c50a25686c482
parent 3ad31c539fe257ebe9d9c6c2df71fb6f905533b9
author Fangrui Song <maskray@google.com> 1542823800 +0000
committer Fangrui Song <maskray@google.com> 1542823800 +0000

[ELF] Write IPLT header in -static -z retpolineplt mode

Summary:
This fixes PR39711: -static -z retpolineplt does not produce retpoline PLT header.
-z now is not relevant.

Statically linked executable does not have PLT, but may have IPLT with no header. When -z retpolineplt is specified, however, the repoline PLT header should still be emitted.

I've checked that this fixes the FreeBSD reproduce in PR39711 and a Linux program statically linked against glibc. The programm print "Hi" rather than SIGILL/SIGSEGV.

getPltEntryOffset may look dirty after this patch, but it can be cleaned up later.

Another possible improvement is that when there are non-preemptible IFUNC symbols (rare case, e.g. -Bsymbolic), both In.Plt and In.Iplt can be non-empty and we'll emit the retpoline PLT header twice.

Reviewers: espindola, emaste, chandlerc, ruiu

Reviewed By: emaste

Subscribers: emaste, arichardson, krytarowski, llvm-commits

Differential Revision: https://reviews.llvm.org/D54782

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@347404 91177308-0d34-0410-b5e6-96231b3b80d8