[lld] r345648 - [ELF] Fallback to sh_link=0 if neither .dynsym nor .symtab exists
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 30 13:54:55 PDT 2018
Author: maskray
Date: Tue Oct 30 13:54:54 2018
New Revision: 345648
URL: http://llvm.org/viewvc/llvm-project?rev=345648&view=rev
Log:
[ELF] Fallback to sh_link=0 if neither .dynsym nor .symtab exists
Summary: .rela.plt may only contain R_*_{,I}RELATIVE relocations and not need a symbol table link. bfd/gold fallbacks to sh_link=0 in this case. Without this patch, ld.lld --strip-all caused lld to dereference a null pointer.
Reviewers: ruiu, grimar, espindola
Reviewed By: ruiu
Subscribers: emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D53881
Modified:
lld/trunk/ELF/SyntheticSections.cpp
lld/trunk/test/ELF/gnu-ifunc-relative.s
Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=345648&r1=345647&r2=345648&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Tue Oct 30 13:54:54 2018
@@ -1491,11 +1491,15 @@ void RelocationBaseSection::addReloc(con
}
void RelocationBaseSection::finalizeContents() {
- // If all relocations are R_*_RELATIVE they don't refer to any
- // dynamic symbol and we don't need a dynamic symbol table. If that
- // is the case, just use the index of the regular symbol table section.
- getParent()->Link = In.DynSymTab ? In.DynSymTab->getParent()->SectionIndex
- : In.SymTab->getParent()->SectionIndex;
+ // If all relocations are R_*_{,I}RELATIVE they don't refer to any dynamic
+ // symbol and we don't need a dynamic symbol table. If that is the case, use
+ // the index of the regular symbol table section (if exists) or 0.
+ if (In.DynSymTab)
+ getParent()->Link = In.DynSymTab->getParent()->SectionIndex;
+ else if (In.SymTab)
+ getParent()->Link = In.SymTab->getParent()->SectionIndex;
+ else
+ getParent()->Link = 0;
if (In.RelaIplt == this || In.RelaPlt == this)
getParent()->Info = In.GotPlt->getParent()->SectionIndex;
Modified: lld/trunk/test/ELF/gnu-ifunc-relative.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/gnu-ifunc-relative.s?rev=345648&r1=345647&r2=345648&view=diff
==============================================================================
--- lld/trunk/test/ELF/gnu-ifunc-relative.s (original)
+++ lld/trunk/test/ELF/gnu-ifunc-relative.s Tue Oct 30 13:54:54 2018
@@ -1,7 +1,9 @@
// REQUIRES: x86
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
-// RUN: ld.lld -static %t.o -o %tout
-// RUN: llvm-readobj -r -t %tout | FileCheck %s
+// RUN: ld.lld --strip-all %t.o -o %t
+// RUN: llvm-readobj -r %t | FileCheck %s
+// RUN: ld.lld %t.o -o %t
+// RUN: llvm-readobj -r -t %t | FileCheck %s --check-prefixes=CHECK,SYM
.type foo STT_GNU_IFUNC
.globl foo
@@ -16,8 +18,8 @@ _start:
// CHECK-NEXT: R_X86_64_IRELATIVE - 0x[[ADDR:.*]]
// CHECK-NEXT: }
-// CHECK: Name: foo
-// CHECK-NEXT: Value: 0x[[ADDR]]
-// CHECK-NEXT: Size: 0
-// CHECK-NEXT: Binding: Global
-// CHECK-NEXT: Type: GNU_IFunc
+// SYM: Name: foo
+// SYM-NEXT: Value: 0x[[ADDR]]
+// SYM-NEXT: Size: 0
+// SYM-NEXT: Binding: Global
+// SYM-NEXT: Type: GNU_IFunc
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