[lld] r361792 - [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Mon May 27 23:34:52 PDT 2019
Author: maskray
Date: Mon May 27 23:34:52 2019
New Revision: 361792
URL: http://llvm.org/viewvc/llvm-project?rev=361792&view=rev
Log:
[ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
This is implemented by creating Undefined (instead of Defined) for such
local STT_SECTION symbols. It allows us to catch errors when there are
relocations to such discarded sections (e.g. in PR41693, ld.bfd and gold
error but we don't). Updated comdat-discarded-error.s checks we emit
friendly error message.
For relocatable-eh-frame.s, ld.lld -r a.o a.o will now error
"STT_SECTION symbol should be defined" because the section .eh_frame
refers to is now an Undefined instead of a Defined.
So I have to change `error()` to `warn()` to retain the output.
Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D61583
Modified:
lld/trunk/ELF/InputFiles.cpp
lld/trunk/ELF/InputSection.cpp
lld/trunk/ELF/Relocations.cpp
lld/trunk/test/ELF/comdat-discarded-error.s
lld/trunk/test/ELF/comdat-discarded-reloc.s
lld/trunk/test/ELF/comdat.s
lld/trunk/test/ELF/invalid-undef-section-symbol.test
lld/trunk/test/ELF/relocatable-eh-frame.s
Modified: lld/trunk/ELF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/ELF/InputFiles.cpp (original)
+++ lld/trunk/ELF/InputFiles.cpp Mon May 27 23:34:52 2019
@@ -997,6 +997,9 @@ template <class ELFT> void ObjFile<ELFT>
if (ESym.st_shndx == SHN_UNDEF)
this->Symbols[I] = make<Undefined>(this, Name, Binding, StOther, Type);
+ else if (Sec == &InputSection::Discarded)
+ this->Symbols[I] = make<Undefined>(this, Name, Binding, StOther, Type,
+ /*DiscardedSecIdx=*/SecIdx);
else
this->Symbols[I] =
make<Defined>(this, Name, Binding, StOther, Type, Value, Size, Sec);
Modified: lld/trunk/ELF/InputSection.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.cpp?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.cpp (original)
+++ lld/trunk/ELF/InputSection.cpp Mon May 27 23:34:52 2019
@@ -438,7 +438,8 @@ void InputSection::copyRelocations(uint8
// hopefully creates a frame that is ignored at runtime.
auto *D = dyn_cast<Defined>(&Sym);
if (!D) {
- error("STT_SECTION symbol should be defined");
+ warn("STT_SECTION symbol should be defined");
+ P->setSymbolAndType(0, 0, false);
continue;
}
SectionBase *Section = D->Section->Repl;
Modified: lld/trunk/ELF/Relocations.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.cpp?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Mon May 27 23:34:52 2019
@@ -681,9 +681,17 @@ static std::string maybeReportDiscarded(
return "";
ArrayRef<Elf_Shdr_Impl<ELFT>> ObjSections =
CHECK(File->getObj().sections(), File);
- std::string Msg =
- "relocation refers to a symbol in a discarded section: " + toString(Sym) +
- "\n>>> defined in " + toString(File);
+
+ std::string Msg;
+ if (Sym.Type == ELF::STT_SECTION) {
+ Msg = "relocation refers to a discarded section: ";
+ Msg += CHECK(
+ File->getObj().getSectionName(&ObjSections[Sym.DiscardedSecIdx]), File);
+ } else {
+ Msg = "relocation refers to a symbol in a discarded section: " +
+ toString(Sym);
+ }
+ Msg += "\n>>> defined in " + toString(File);
Elf_Shdr_Impl<ELFT> ELFSec = ObjSections[Sym.DiscardedSecIdx - 1];
if (ELFSec.sh_type != SHT_GROUP)
Modified: lld/trunk/test/ELF/comdat-discarded-error.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/comdat-discarded-error.s?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat-discarded-error.s (original)
+++ lld/trunk/test/ELF/comdat-discarded-error.s Mon May 27 23:34:52 2019
@@ -5,7 +5,7 @@
# RUN: echo '.section .text.foo,"axG", at progbits,foo,comdat; .globl bar; bar:' | \
# RUN: llvm-mc -filetype=obj -triple=x86_64 - -o %t3.o
-# RUN: not ld.lld %t1.o %t2.o %t3.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld %t2.o %t3.o %t1.o -o /dev/null 2>&1 | FileCheck %s
# CHECK: error: relocation refers to a symbol in a discarded section: bar
# CHECK-NEXT: >>> defined in {{.*}}3.o
@@ -13,6 +13,16 @@
# CHECK-NEXT: >>> prevailing definition is in {{.*}}2.o
# CHECK-NEXT: >>> referenced by {{.*}}1.o:(.text+0x1)
+# CHECK: error: relocation refers to a discarded section: .text.foo
+# CHECK-NEXT: >>> defined in {{.*}}1.o
+# CHECK-NEXT: >>> section group signature: foo
+# CHECK-NEXT: >>> prevailing definition is in {{.*}}2.o
+# CHECK-NEXT: >>> referenced by {{.*}}1.o:(.data+0x0)
+
.globl _start
_start:
jmp bar
+
+.section .text.foo,"axG", at progbits,foo,comdat
+.data
+ .quad .text.foo
Modified: lld/trunk/test/ELF/comdat-discarded-reloc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/comdat-discarded-reloc.s?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat-discarded-reloc.s (original)
+++ lld/trunk/test/ELF/comdat-discarded-reloc.s Mon May 27 23:34:52 2019
@@ -1,7 +1,7 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/comdat-discarded-reloc.s -o %t2.o
-# RUN: ld.lld -gc-sections %t.o %t2.o -o %t
+# RUN: ld.lld -gc-sections --noinhibit-exec %t.o %t2.o -o /dev/null
## ELF spec doesn't allow a relocation to point to a deduplicated
## COMDAT section. Unfortunately this happens in practice (e.g. .eh_frame)
Modified: lld/trunk/test/ELF/comdat.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/comdat.s?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat.s (original)
+++ lld/trunk/test/ELF/comdat.s Mon May 27 23:34:52 2019
@@ -1,7 +1,7 @@
// REQUIRES: x86
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/comdat.s -o %t2.o
-// RUN: ld.lld -shared %t.o %t.o %t2.o -o %t
+// RUN: ld.lld -shared %t.o %t2.o -o %t
// RUN: llvm-objdump -d %t | FileCheck %s
// RUN: llvm-readobj -S --symbols %t | FileCheck --check-prefix=READ %s
@@ -31,9 +31,7 @@ foo:
// CHECK-EMPTY:
// CHECK-NEXT: bar:
// 0x1000 - 0x1001 - 5 = -6
-// 0 - 0x1006 - 5 = -4107
// CHECK-NEXT: 1001: {{.*}} callq -6
-// CHECK-NEXT: 1006: {{.*}} callq -4107
.section .text3,"axG", at progbits,zed,comdat,unique,0
Modified: lld/trunk/test/ELF/invalid-undef-section-symbol.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/invalid-undef-section-symbol.test?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/test/ELF/invalid-undef-section-symbol.test (original)
+++ lld/trunk/test/ELF/invalid-undef-section-symbol.test Mon May 27 23:34:52 2019
@@ -1,5 +1,5 @@
# RUN: yaml2obj %s -o %t.o
-# RUN: not ld.lld -r %t.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld -r --fatal-warnings %t.o -o /dev/null 2>&1 | FileCheck %s
# We used to crash at this.
# CHECK: STT_SECTION symbol should be defined
Modified: lld/trunk/test/ELF/relocatable-eh-frame.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/relocatable-eh-frame.s?rev=361792&r1=361791&r2=361792&view=diff
==============================================================================
--- lld/trunk/test/ELF/relocatable-eh-frame.s (original)
+++ lld/trunk/test/ELF/relocatable-eh-frame.s Mon May 27 23:34:52 2019
@@ -1,10 +1,12 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
-# RUN: ld.lld -r %t.o %t.o -o %t
+# RUN: ld.lld -r %t.o %t.o -o %t 2>&1 | FileCheck --check-prefix=WARN %s
# RUN: llvm-readobj -r %t | FileCheck %s
# RUN: ld.lld %t -o %t.so -shared
# RUN: llvm-objdump -h %t.so | FileCheck --check-prefix=DSO %s
+# WARN: STT_SECTION symbol should be defined
+
# DSO: .eh_frame 00000034
# CHECK: Relocations [
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