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Set entry address to 0x0 if no _start symbol 

Differential revision: https://reviews.llvm.org/D23925

llvm-svn: 280912
This commit is contained in:
Eugene Leviant 2016-09-08 08:57:51 +00:00
parent 6c55f0e35e
commit 3967ea05a9
10 changed files with 47 additions and 40 deletions
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2
lld/ELF/Config.h
View File

@ -127,7 +127,7 @@ struct Configuration {
ELFKind EKind = ELFNoneKind;
uint16_t DefaultSymbolVersion = llvm::ELF::VER_NDX_GLOBAL;
uint16_t EMachine = llvm::ELF::EM_NONE;
uint64_t EntryAddr = -1;
uint64_t EntryAddr = 0;
uint64_t ImageBase;
uint64_t ZStackSize = -1;
unsigned LtoJobs;

31
lld/ELF/Driver.cpp
View File

@ -575,11 +575,6 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
Config->Mips64EL =
(Config->EMachine == EM_MIPS && Config->EKind == ELF64LEKind);
// Add entry symbol. Note that AMDGPU binaries have no entry points.
if (Config->Entry.empty() && !Config->Shared && !Config->Relocatable &&
Config->EMachine != EM_AMDGPU)
Config->Entry = (Config->EMachine == EM_MIPS) ? "__start" : "_start";
// Default output filename is "a.out" by the Unix tradition.
if (Config->OutputFile.empty())
Config->OutputFile = "a.out";
@ -588,13 +583,6 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
for (auto *Arg : Args.filtered(OPT_trace_symbol))
Symtab.trace(Arg->getValue());
// Set either EntryAddr (if S is a number) or EntrySym (otherwise).
if (!Config->Entry.empty()) {
StringRef S = Config->Entry;
if (S.getAsInteger(0, Config->EntryAddr))
Config->EntrySym = Symtab.addUndefined(S);
}
// Initialize Config->ImageBase.
if (auto *Arg = Args.getLastArg(OPT_image_base)) {
StringRef S = Arg->getValue();
@ -606,8 +594,27 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
Config->ImageBase = Config->Pic ? 0 : Target->DefaultImageBase;
}
// Add all files to the symbol table. After this, the symbol table
// contains all known names except a few linker-synthesized symbols.
for (std::unique_ptr<InputFile> &F : Files)
Symtab.addFile(std::move(F));
// Add the start symbol.
// It initializes either Config->Entry or Config->EntryAddr.
// Note that AMDGPU binaries have no entries.
if (!Config->Entry.empty()) {
// It is either "-e <addr>" or "-e <symbol>".
if (Config->Entry.getAsInteger(0, Config->EntryAddr))
Config->EntrySym = Symtab.addUndefined(Config->Entry);
} else if (!Config->Shared && !Config->Relocatable &&
Config->EMachine != EM_AMDGPU) {
// -e was not specified. Use the default start symbol name
// if it is resolvable.
Config->Entry = (Config->EMachine == EM_MIPS) ? "__start" : "_start";
if (Symtab.find(Config->Entry))
Config->EntrySym = Symtab.addUndefined(Config->Entry);
}
if (HasError)
return; // There were duplicate symbols or incompatible files

4
lld/ELF/Writer.cpp
View File

@ -1186,9 +1186,7 @@ template <class ELFT> void Writer<ELFT>::setPhdrs() {
template <class ELFT> static typename ELFT::uint getEntryAddr() {
if (Symbol *S = Config->EntrySym)
return S->body()->getVA<ELFT>();
if (Config->EntryAddr != uint64_t(-1))
return Config->EntryAddr;
return 0;
return Config->EntryAddr;
}
template <class ELFT> static uint8_t getELFEncoding() {

2
lld/test/ELF/arm-gnu-ifunc.s
View File

@ -70,7 +70,7 @@ _start:
// CHECK-NEXT: Section: .rel.plt
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: _start (6)
// CHECK-NEXT: Name: _start (38)
// CHECK-NEXT: Value: 0x11008
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global

18
lld/test/ELF/edata-etext.s
View File

@ -69,15 +69,6 @@
# CHECK-NEXT: Section: Undefined
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: _start
# CHECK-NEXT: Value: 0x11000
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: None
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .text
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: _edata
# CHECK-NEXT: Value: 0x12002
# CHECK-NEXT: Size: 0
@ -104,6 +95,15 @@
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: Absolute
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: _start (20)
# CHECK-NEXT: Value: 0x11000
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Global (0x1)
# CHECK-NEXT: Type: None (0x0)
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .text (0x1)
# CHECK-NEXT: }
# CHECK-NEXT: ]
.global _start,_end,_etext,_edata

4
lld/test/ELF/entry.s
View File

@ -1,5 +1,6 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
# RUN: not ld.lld %t1 -o %t2
# RUN: ld.lld %t1 -o %t2
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=NOENTRY %s
# RUN: ld.lld %t1 -o %t2 -e entry
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=SYM %s
# RUN: ld.lld %t1 -shared -o %t2 -e entry
@ -11,6 +12,7 @@
# RUN: ld.lld %t1 -o %t2 -e 0777
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=OCT %s
# NOENTRY: Entry: 0x0
# SYM: Entry: 0x11000
# DSO: Entry: 0x1000
# DEC: Entry: 0x1000

3
lld/test/ELF/linkerscript/symbols-synthetic.s
View File

@ -54,8 +54,9 @@
# RUN: ld.lld -o %t1 --eh-frame-hdr --script %t.script %t
# SIMPLE: 0000000000000160 .foo 00000000 .hidden _end_sec
# SIMPLE: 0000000000000158 .foo 00000000 _begin_sec
# SIMPLE-NEXT: 0000000000000158 .foo 00000000 _begin_sec
# SIMPLE-NEXT: 0000000000000160 *ABS* 00000000 _end_sec_abs
# SIMPLE-NEXT: 0000000000001048 .text 00000000 _start
# SIMPLE-NEXT: 0000000000000158 .foo 00000000 begin_foo
# SIMPLE-NEXT: 0000000000000160 .foo 00000000 end_foo
# SIMPLE-NEXT: 0000000000000008 .foo 00000000 size_foo_1

2
lld/test/ELF/reproduce-windows.s
View File

@ -5,7 +5,7 @@
# RUN: mkdir -p %t.dir/build
# RUN: llvm-mc %s -o %t.dir/build/foo.o -filetype=obj -triple=x86_64-pc-linux
# RUN: cd %t.dir
# RUN: not ld.lld build/foo.o --reproduce repro
# RUN: ld.lld build/foo.o --reproduce repro
# RUN: cpio -t < repro.cpio | FileCheck %s
# CHECK: repro/response.txt

18
lld/test/ELF/resolution.s
View File

@ -19,15 +19,6 @@
// CHECK-NEXT: Section: Undefined (0x0)
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: _start
// CHECK-NEXT: Value:
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global
// CHECK-NEXT: Type: None
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: CommonStrong_with_CommonStrong
// CHECK-NEXT: Value:
// CHECK-NEXT: Size: 63
@ -315,6 +306,15 @@
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: Undefined
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: _start (929)
// CHECK-NEXT: Value: 0x11000
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global (0x1)
// CHECK-NEXT: Type: None (0x0)
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text (0x1)
// CHECK-NEXT: }
// CHECK-NEXT: ]
.globl _start

3
lld/test/ELF/undef-start.s
View File

@ -1,4 +1,3 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
# RUN: not ld.lld %t -o %t2 2>&1 | FileCheck %s
# CHECK: undefined symbol: _start
# RUN: ld.lld %t -o %t2 2>&1
# REQUIRES: x86