[lld] r361830 - Reland D61583 [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Tue May 28 07:34:29 PDT 2019
Author: maskray
Date: Tue May 28 07:34:28 2019
New Revision: 361830
URL: http://llvm.org/viewvc/llvm-project?rev=361830&view=rev
Log:
Reland D61583 [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.
rLLD361144 inadvertently enabled the error for --gdb-index
(in LLDDwarfObj<ELFT>::findAux()).
Relocations from .debug_info (not in comdat) to .text.* (in comdat) for
DW_AT_low_pc are common. If an .text.* was discarded, rLLD361144 would error,
which was unexpected. (Note, if we don't error as this patch does,
InputSection::relocateNonAlloc() will resolve such relocations).
Added:
lld/trunk/test/ELF/comdat-discarded-gdb-index.s
Modified:
lld/trunk/ELF/DWARF.cpp
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/DWARF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/DWARF.cpp?rev=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/ELF/DWARF.cpp (original)
+++ lld/trunk/ELF/DWARF.cpp Tue May 28 07:34:28 2019
@@ -93,8 +93,11 @@ LLDDwarfObj<ELFT>::findAux(const InputSe
uint32_t SecIndex = File->getSectionIndex(Sym);
// Broken debug info can point to a non-Defined symbol.
- auto *DR = dyn_cast<Defined>(&File->getRelocTargetSym(Rel));
+ Symbol &S = File->getRelocTargetSym(Rel);
+ auto *DR = dyn_cast<Defined>(&S);
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" +
Modified: lld/trunk/ELF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/ELF/InputFiles.cpp (original)
+++ lld/trunk/ELF/InputFiles.cpp Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.cpp (original)
+++ lld/trunk/ELF/InputSection.cpp Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat-discarded-error.s (original)
+++ lld/trunk/test/ELF/comdat-discarded-error.s Tue May 28 07:34:28 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
Added: lld/trunk/test/ELF/comdat-discarded-gdb-index.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/comdat-discarded-gdb-index.s?rev=361830&view=auto
==============================================================================
--- lld/trunk/test/ELF/comdat-discarded-gdb-index.s (added)
+++ lld/trunk/test/ELF/comdat-discarded-gdb-index.s Tue May 28 07:34:28 2019
@@ -0,0 +1,63 @@
+# 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", at progbits,foo,comdat
+.globl foo
+.Lfunc_begin0:
+foo:
+ ret
+.Lfunc_end0:
+
+.section .debug_abbrev,"", at 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,"", at 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,"", at 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:
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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat-discarded-reloc.s (original)
+++ lld/trunk/test/ELF/comdat-discarded-reloc.s Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/test/ELF/comdat.s (original)
+++ lld/trunk/test/ELF/comdat.s Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/test/ELF/invalid-undef-section-symbol.test (original)
+++ lld/trunk/test/ELF/invalid-undef-section-symbol.test Tue May 28 07:34:28 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=361830&r1=361829&r2=361830&view=diff
==============================================================================
--- lld/trunk/test/ELF/relocatable-eh-frame.s (original)
+++ lld/trunk/test/ELF/relocatable-eh-frame.s Tue May 28 07:34:28 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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