From ad667661c48c06807a87851d4b7360d97eb79b16 Mon Sep 17 00:00:00 2001 From: George Rimar Date: Mon, 10 Dec 2018 09:13:36 +0000 Subject: [PATCH] [ELF] - Allow discarding .dynsym from the linker script. This is a part of https://bugs.llvm.org/show_bug.cgi?id=39810. The patch allows discarding the .dynsym section using linker script. Differential revision: https://reviews.llvm.org/D55218 llvm-svn: 348748 --- lld/ELF/LinkerScript.cpp | 4 ++-- lld/ELF/SyntheticSections.cpp | 11 ++++++++--- lld/test/ELF/linkerscript/discard-section-err.s | 5 ++--- 3 files changed, 12 insertions(+), 8 deletions(-) diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp index dad43d5b..e37b4a3 100644 --- a/lld/ELF/LinkerScript.cpp +++ b/lld/ELF/LinkerScript.cpp @@ -415,8 +415,8 @@ LinkerScript::computeInputSections(const InputSectionDescription *Cmd) { void LinkerScript::discard(ArrayRef V) { for (InputSection *S : V) { - if (S == In.ShStrTab || S == In.Dynamic || S == In.DynSymTab || - S == In.RelaDyn || S == In.RelrDyn) + if (S == In.ShStrTab || S == In.Dynamic || S == In.RelaDyn || + S == In.RelrDyn) error("discarding " + S->Name + " section is not allowed"); // You can discard .hash and .gnu.hash sections by linker scripts. Since diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp index d3a7a27..293d845 100644 --- a/lld/ELF/SyntheticSections.cpp +++ b/lld/ELF/SyntheticSections.cpp @@ -1508,7 +1508,10 @@ void RelocationBaseSection::finalizeContents() { // relocations due to IFUNC (e.g. strcpy). sh_link will be set to 0 in that // case. InputSection *SymTab = Config->Relocatable ? In.SymTab : In.DynSymTab; - getParent()->Link = SymTab ? SymTab->getParent()->SectionIndex : 0; + if (SymTab && SymTab->getParent()) + getParent()->Link = SymTab->getParent()->SectionIndex; + else + getParent()->Link = 0; if (In.RelaIplt == this || In.RelaPlt == this) getParent()->Info = In.GotPlt->getParent()->SectionIndex; @@ -2126,7 +2129,8 @@ GnuHashTableSection::GnuHashTableSection() } void GnuHashTableSection::finalizeContents() { - getParent()->Link = In.DynSymTab->getParent()->SectionIndex; + if (OutputSection *Sec = In.DynSymTab->getParent()) + getParent()->Link = Sec->SectionIndex; // Computes bloom filter size in word size. We want to allocate 12 // bits for each symbol. It must be a power of two. @@ -2256,7 +2260,8 @@ HashTableSection::HashTableSection() } void HashTableSection::finalizeContents() { - getParent()->Link = In.DynSymTab->getParent()->SectionIndex; + if (OutputSection *Sec = In.DynSymTab->getParent()) + getParent()->Link = Sec->SectionIndex; unsigned NumEntries = 2; // nbucket and nchain. NumEntries += In.DynSymTab->getNumSymbols(); // The chain entries. diff --git a/lld/test/ELF/linkerscript/discard-section-err.s b/lld/test/ELF/linkerscript/discard-section-err.s index 13dd688..82105b5 100644 --- a/lld/test/ELF/linkerscript/discard-section-err.s +++ b/lld/test/ELF/linkerscript/discard-section-err.s @@ -12,10 +12,9 @@ # RUN: FileCheck -check-prefix=DYNAMIC %s # DYNAMIC: discarding .dynamic section is not allowed +## We allow discarding .dynsym, check we don't crash. # RUN: echo "SECTIONS { /DISCARD/ : { *(.dynsym) } }" > %t.script -# RUN: not ld.lld -pie -o %t --script %t.script %t.o 2>&1 | \ -# RUN: FileCheck -check-prefix=DYNSYM %s -# DYNSYM: discarding .dynsym section is not allowed +# RUN: ld.lld -pie -o %t --script %t.script %t.o ## We allow discarding .dynstr, check we don't crash. # RUN: echo "SECTIONS { /DISCARD/ : { *(.dynstr) } }" > %t.script -- 2.7.4