maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[ELF] Error on relocations to local undefined symbols 

For a reference to a local symbol, ld.bfd and gold error if the symbol
is defined in a discarded section but accept it if the symbol is
undefined. This inconsistent behavior seems unnecessary for us (it
probably makes sense for them as they differentiate local/global
symbols, the error would mean more code).

Weaken the condition to getSymbol(Config->IsMips64EL) == 0 to catch such
errors. The symbol index can be 0 (e.g. R_*_NONE R_ARM_V4BX) and we shouldn't error on them.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61563

llvm-svn: 361144
This commit is contained in:
Fangrui Song 2019-05-20 11:25:55 +00:00
parent 95805bc425
commit 7c7425483a
2 changed files with 9 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lld/ELF/Relocations.cpp
View File

@ -675,7 +675,7 @@ static int64_t computeAddend(const RelTy &Rel, const RelTy *End,
// Returns true if this function printed out an error message.
static bool maybeReportUndefined(Symbol &Sym, InputSectionBase &Sec,
uint64_t Offset) {
if (Sym.isLocal() || !Sym.isUndefined() || Sym.isWeak())
if (!Sym.isUndefined() || Sym.isWeak())
return false;
bool CanBeExternal =
@ -1012,7 +1012,8 @@ template <class ELFT, class RelTy>
static void scanReloc(InputSectionBase &Sec, OffsetGetter &GetOffset, RelTy *&I,
RelTy *End) {
const RelTy &Rel = *I;
Symbol &Sym = Sec.getFile<ELFT>()->getRelocTargetSym(Rel);
uint32_t SymIndex = Rel.getSymbol(Config->IsMips64EL);
Symbol &Sym = Sec.getFile<ELFT>()->getSymbol(SymIndex);
RelType Type;
// Deal with MIPS oddity.
@ -1028,8 +1029,9 @@ static void scanReloc(InputSectionBase &Sec, OffsetGetter &GetOffset, RelTy *&I,
if (Offset == uint64_t(-1))
return;
// Skip if the target symbol is an erroneous undefined symbol.
if (maybeReportUndefined(Sym, Sec, Rel.r_offset))
// Error if the target symbol is undefined. Symbol index 0 may be used by
// marker relocations, e.g. R_*_NONE and R_ARM_V4BX. Don't error on them.
if (SymIndex != 0 && maybeReportUndefined(Sym, Sec, Rel.r_offset))
return;
const uint8_t *RelocatedAddr = Sec.data().begin() + Rel.r_offset;

8
lld/test/ELF/local-undefined-symbol.s
View File

@ -1,10 +1,8 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
# RUN: ld.lld %t -o %t1
# RUN: llvm-readobj --symbols %t1 | FileCheck %s
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: not ld.lld %t.o -o %t 2>&1 | FileCheck %s
# CHECK: Symbols [
# CHECK-NOT: Name: foo
# CHECK: error: undefined symbol: foo
.global _start
_start: