intel/llvm
1
0
Fork 0
mirror of https://github.com/intel/llvm.git synced 2026-01-26 12:26:52 +08:00
Code Issues Packages Projects Releases Wiki Activity

[ELF] Shared libraries should have entry point

Browse Source 
Shared libraries should have entry set following the same rules as for
regular binaries. The only difference is that in case the default entry
point (_start or __start) isn't found (unless it was set explicitly), we
shouldn't give a warning as in case of regular binaries.

Differential Revision: https://reviews.llvm.org/D27497

llvm-svn: 288878
This commit is contained in:
Petr Hosek
2016-12-07 02:26:16 +00:00
parent 668bebed6d
commit 2f50fef095
4 changed files with 38 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
lld/ELF/Config.h
View File

@@ -107,6 +107,7 @@ struct Configuration {
bool GcSections;
bool GdbIndex;
bool GnuHash = false;
bool HasEntry = false;
bool ICF;
bool Mips64EL = false;
bool MipsN32Abi = false;

4
lld/ELF/Driver.cpp
View File

@@ -521,6 +521,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
Config->EnableNewDtags = !Args.hasArg(OPT_disable_new_dtags);
Config->ExportDynamic = Args.hasArg(OPT_export_dynamic);
Config->FatalWarnings = Args.hasArg(OPT_fatal_warnings);
Config->HasEntry = Args.hasArg(OPT_entry);
Config->GcSections = getArg(Args, OPT_gc_sections, OPT_no_gc_sections, false);
Config->GdbIndex = Args.hasArg(OPT_gdb_index);
Config->ICF = Args.hasArg(OPT_icf);
@@ -786,8 +787,7 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
// It is either "-e <addr>" or "-e <symbol>".
if (!Config->Entry.getAsInteger(0, Config->EntryAddr))
Config->Entry = "";
} else if (!Config->Shared && !Config->Relocatable &&
Config->EMachine != EM_AMDGPU) {
} else if (!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";

10
lld/ELF/Writer.cpp
View File

@@ -1410,14 +1410,16 @@ template <class ELFT> typename ELFT::uint Writer<ELFT>::getEntryAddr() {
// Case 4
if (OutputSectionBase *Sec = findSection(".text")) {
warn("cannot find entry symbol " + Config->Entry + "; defaulting to 0x" +
utohexstr(Sec->Addr));
if (!Config->Shared || Config->HasEntry)
warn("cannot find entry symbol " + Config->Entry + "; defaulting to 0x" +
utohexstr(Sec->Addr));
return Sec->Addr;
}
// Case 5
warn("cannot find entry symbol " + Config->Entry +
"; not setting start address");
if (!Config->Shared || Config->HasEntry)
warn("cannot find entry symbol " + Config->Entry +
"; not setting start address");
return 0;
}

29
lld/test/ELF/gc-sections-keep-shared-start.s Normal file
View File

@@ -0,0 +1,29 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
# RUN: ld.lld -shared --gc-sections -o %t1 %t
# RUN: llvm-readobj --elf-output-style=GNU --file-headers --symbols %t1
# | FileCheck %s
# CHECK: Entry point address: 0x1000
# CHECK: 0000000000001000 0 FUNC LOCAL HIDDEN 4 _start
# CHECK: 0000000000001006 0 FUNC LOCAL HIDDEN 4 internal
# CHECK: 0000000000001005 0 FUNC GLOBAL DEFAULT 4 foobar
.section .text.start,"ax"
.globl _start
.type _start,%function
.hidden _start
_start:
jmp internal
.section .text.foobar,"ax"
.globl foobar
.type foobar,%function
foobar:
ret
.section .text.internal,"ax"
.globl internal
.hidden internal
.type internal,%function
internal:
ret