(In effect, reverting "[ELF] Error on relocations to STT_SECTION symbols if the sections were discarded".)
It caused debug info problems in LibreOffice [1] and Chromium/V8 [2].
Reverting until those can be fixed.
It also reverts r362497 "STT_SECTION symbol should be defined" on .eh_frame, .debug*, .zdebug* and .gcc_except_table"
which was landed as a follow-up to the above.
> With -r or --emit-relocs, we warn `STT_SECTION symbol should be defined`
> on relocations to discarded section symbol. This was added as an error
> in rLLD319404, but was not so effective before D61583 (it turned the
> error to a warning).
>
> Relocations from .eh_frame .debug* .zdebug* .gcc_except_table to
> discarded .text are very common and somewhat expected. Don't warn/error
> on them. As a reference, ld.bfd has a similar logic in
> _bfd_elf_default_action_discarded() to allow these cases.
>
> Delete invalid-undef-section-symbol.test because what it intended to
> check is now covered by the updated comdat-discarded-reloc.s
>
> Delete relocatable-eh-frame.s because we allow relocations from
> .eh_frame as a special case now.
And finally it reverts r362218 "[ELF] Replace a dead test in getSymVA() with assert()"
as that also depended on the main change reverted here.
> Symbols relative to discarded comdat sections are Undefined instead of
> Defined now (after D59649 and D61583). The `== &InputSection::Discarded`
> test becomes dead. I cannot find a test related to this behavior.
[1] http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-
20190603/659848.html
[2] https://bugs.chromium.org/p/chromium/issues/detail?id=978067
llvm-svn: 364321
uint32_t SecIndex = File->getSectionIndex(Sym);
// Broken debug info can point to a non-Defined symbol.
- Symbol &S = File->getRelocTargetSym(Rel);
- auto *DR = dyn_cast<Defined>(&S);
+ auto *DR = dyn_cast<Defined>(&File->getRelocTargetSym(Rel));
if (!DR) {
- if (S.isSection())
- return None;
RelType Type = Rel.getType(Config->IsMips64EL);
if (Type != Target->NoneRel)
error(toString(File) + ": relocation " + lld::toString(Type) + " at 0x" +
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);
for (const RelTy &Rel : Rels) {
RelType Type = Rel.getType(Config->IsMips64EL);
- const ObjFile<ELFT> *File = getFile<ELFT>();
- Symbol &Sym = File->getRelocTargetSym(Rel);
+ Symbol &Sym = getFile<ELFT>()->getRelocTargetSym(Rel);
auto *P = reinterpret_cast<typename ELFT::Rela *>(Buf);
Buf += sizeof(RelTy);
// .eh_frame is horribly special and can reference discarded sections. To
// avoid having to parse and recreate .eh_frame, we just replace any
// relocation in it pointing to discarded sections with R_*_NONE, which
- // hopefully creates a frame that is ignored at runtime. Also, don't warn
- // on .gcc_except_table and debug sections.
- //
- // See the comment in maybeReportUndefined for PPC64 .toc .
+ // hopefully creates a frame that is ignored at runtime.
auto *D = dyn_cast<Defined>(&Sym);
if (!D) {
- if (!Sec->Name.startswith(".debug") &&
- !Sec->Name.startswith(".zdebug") && Sec->Name != ".eh_frame" &&
- Sec->Name != ".gcc_except_table" && Sec->Name != ".toc") {
- uint32_t SecIdx = cast<Undefined>(Sym).DiscardedSecIdx;
- Elf_Shdr_Impl<ELFT> Sec =
- CHECK(File->getObj().sections(), File)[SecIdx];
- warn("relocation refers to a discarded section: " +
- CHECK(File->getObj().getSectionName(&Sec), File) +
- "\n>>> referenced by " + getObjMsg(P->r_offset));
- }
- P->setSymbolAndType(0, 0, false);
+ error("STT_SECTION symbol should be defined");
continue;
}
SectionBase *Section = D->Section->Repl;
return "";
ArrayRef<Elf_Shdr_Impl<ELFT>> ObjSections =
CHECK(File->getObj().sections(), 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);
+ std::string Msg =
+ "relocation refers to a symbol in a discarded section: " + toString(Sym) +
+ "\n>>> defined in " + toString(File);
Elf_Shdr_Impl<ELFT> ELFSec = ObjSections[Sym.DiscardedSecIdx - 1];
if (ELFSec.sh_type != SHT_GROUP)
auto &D = cast<Defined>(Sym);
SectionBase *IS = D.Section;
+ // According to the ELF spec reference to a local symbol from outside
+ // the group are not allowed. Unfortunately .eh_frame breaks that rule
+ // and must be treated specially. For now we just replace the symbol with
+ // 0.
+ if (IS == &InputSection::Discarded)
+ return 0;
+
// This is an absolute symbol.
if (!IS)
return D.Value;
- assert(IS != &InputSection::Discarded);
IS = IS->Repl;
uint64_t Offset = D.Value;
-.global bar, _start
+.section .text.bar1,"aG",@progbits,group,comdat
-.section .text.foo,"aG",@progbits,group,comdat
-
-.section .text
-_start:
- .quad .text.foo
- .quad bar
+.section .text.bar2
+.global bar
+bar:
+ .quad .text.bar1
# RUN: echo '.section .text.foo,"axG",@progbits,foo,comdat; .globl bar; bar:' |\
# RUN: llvm-mc -filetype=obj -triple=x86_64 - -o %t3.o
-# RUN: not ld.lld %t2.o %t3.o %t1.o -o /dev/null 2>&1 | FileCheck %s
+# RUN: not ld.lld %t1.o %t2.o %t3.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
# 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",@progbits,foo,comdat
-.data
- .quad .text.foo
+++ /dev/null
-# REQUIRES: x86
-# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
-# RUN: ld.lld --gdb-index %t.o %t.o -o %t
-
-## .debug_info has a relocation to .text.foo . The second %t.o is discarded.
-## Check we don't error on the relocation.
-# CHECK: .rela.debug_info {
-# CHECK-NEXT: 0xC R_X86_64_64 .text.foo 0x0
-
-.section .text.foo,"axG",@progbits,foo,comdat
-.globl foo
-.Lfunc_begin0:
-foo:
- ret
-.Lfunc_end0:
-
-.section .debug_abbrev,"",@progbits
- .byte 1 # Abbreviation Code
- .byte 17 # DW_TAG_compile_unit
- .byte 1 # DW_CHILDREN_yes
- .byte 17 # DW_AT_low_pc
- .byte 1 # DW_FORM_addr
- .byte 18 # DW_AT_high_pc
- .byte 6 # DW_FORM_data4
- .ascii "\264B" # DW_AT_GNU_pubnames
- .byte 25 # DW_FORM_flag_present
- .byte 0 # EOM(1)
- .byte 0 # EOM(2)
- .byte 2 # Abbreviation Code
- .byte 46 # DW_TAG_subprogram
- .byte 0 # DW_CHILDREN_no
- .byte 3 # DW_AT_name
- .byte 8 # DW_FORM_string
- .byte 0 # EOM(1)
- .byte 0 # EOM(2)
- .byte 0
-
-.section .debug_info,"",@progbits
-.Lcu_begin0:
- .long .Lcu_end0 - .Lcu_begin0 - 4
- .short 4 # DWARF version number
- .long 0 # Offset Into Abbrev. Section
- .byte 4 # Address Size
-.Ldie0:
- .byte 1 # Abbrev [1] DW_TAG_compile_unit
- .quad .Lfunc_begin0 # DW_AT_low_pc
- .long .Lfunc_end0 - .Lfunc_begin0 # DW_AT_high_pc
- .byte 2 # Abbrev [2] DW_TAG_subprogram
- .asciz "foo" # DW_AT_name
- .byte 0
-.Lcu_end0:
-
-.section .debug_gnu_pubnames,"",@progbits
- .long .LpubNames_end0 - .LpubNames_begin0
-.LpubNames_begin0:
- .short 2 # Version
- .long .Lcu_begin0 # CU Offset
- .long .Lcu_end0 - .Lcu_begin0
- .long .Ldie0 - .Lcu_begin0
- .byte 48 # Attributes: FUNCTION, EXTERNAL
- .asciz "foo" # External Name
- .long 0
-.LpubNames_end0:
# 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 --noinhibit-exec %t2.o %t.o -o /dev/null
-# RUN: ld.lld -r %t2.o %t.o -o %t 2>&1 | FileCheck --check-prefix=WARN %s
-# RUN: llvm-readobj -r %t | FileCheck --check-prefix=RELOC %s
+# RUN: ld.lld -gc-sections %t.o %t2.o -o %t
## ELF spec doesn't allow a relocation to point to a deduplicated
## COMDAT section. Unfortunately this happens in practice (e.g. .eh_frame)
## Test case checks we do not crash.
-# WARN: warning: relocation refers to a discarded section: .text.bar1
-# WARN-NEXT: >>> referenced by {{.*}}.o:(.rela.text.bar2+0x0)
-# WARN-NOT: warning
+.global bar, _start
-# RELOC: .rela.eh_frame {
-# RELOC-NEXT: R_X86_64_NONE
-# RELOC-NEXT: }
-# RELOC-NEXT: .rela.debug_foo {
-# RELOC-NEXT: R_X86_64_NONE
-# RELOC-NEXT: }
-# RELOC-NEXT: .rela.gcc_except_table {
-# RELOC-NEXT: R_X86_64_NONE
-# RELOC-NEXT: }
+.section .text.foo,"aG",@progbits,group,comdat
-.section .text.bar1,"aG",@progbits,group,comdat
-
-## .text.bar1 in this file is discarded. Warn on the relocation.
-.section .text.bar2,"ax"
-.globl bar
-bar:
- .quad .text.bar1
-
-## Don't warn on .eh_frame, .debug*, .zdebug*, or .gcc_except_table
-.section .eh_frame,"a"
- .quad .text.bar1
-
-.section .debug_foo
- .quad .text.bar1
-
-.section .gcc_except_table,"a"
- .quad .text.bar1
+.section .text
+_start:
+ .quad .text.foo
+ .quad bar
// 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 %t2.o -o %t
+// RUN: ld.lld -shared %t.o %t.o %t2.o -o %t
// RUN: llvm-objdump -d %t | FileCheck %s
// RUN: llvm-readobj -S --symbols %t | FileCheck --check-prefix=READ %s
// 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",@progbits,zed,comdat,unique,0
--- /dev/null
+# RUN: yaml2obj %s -o %t.o
+# RUN: not ld.lld -r %t.o -o /dev/null 2>&1 | FileCheck %s
+
+# We used to crash at this.
+# CHECK: STT_SECTION symbol should be defined
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ - Name: .rela.text
+ Type: SHT_RELA
+ AddressAlign: 0x0000000000000008
+ Info: .text
+ Relocations:
+ - Offset: 0x0000000000000000
+ Symbol: .text
+ Type: R_X86_64_NONE
+Symbols:
+ - Name: .text
+ Type: STT_SECTION
--- /dev/null
+# 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: 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
+
+# DSO: .eh_frame 00000034
+
+# CHECK: Relocations [
+# CHECK-NEXT: Section ({{.*}}) .rela.eh_frame {
+# CHECK-NEXT: 0x20 R_X86_64_PC32 .foo 0x0
+# CHECK-NEXT: 0x50 R_X86_64_NONE - 0x0
+# CHECK-NEXT: }
+# CHECK-NEXT: ]
+
+.section .foo,"aG",@progbits,bar,comdat
+.cfi_startproc
+.cfi_endproc
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