maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

ELF2: Support --entry=<addr>. 

If an argument for --entry is a number, that's not a symbol name but
an absolute address. If that's the case, the address is directly set
to ELF header's e_entry.

llvm-svn: 250334
This commit is contained in:
Rui Ueyama 2015-10-14 22:20:57 +00:00
parent f9e0b253ad
commit 2b675074fe
4 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
lld/ELF/Config.h
View File

@ -58,6 +58,7 @@ struct Configuration {
bool ZNow = false;
ELFKind EKind = ELFNoneKind;
uint16_t EMachine = llvm::ELF::EM_NONE;
uint64_t EntryAddr = -1;
};
extern Configuration *Config;

6
lld/ELF/Driver.cpp
View File

@ -201,7 +201,11 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
// Add entry symbol.
if (Config->Entry.empty())
Config->Entry = (Config->EMachine == EM_MIPS) ? "__start" : "_start";
Config->EntrySym = Symtab.addUndefined(Config->Entry);
// Set either EntryAddr (if S is a number) or EntrySym (otherwise).
StringRef S = Config->Entry;
if (S.getAsInteger(0, Config->EntryAddr))
Config->EntrySym = Symtab.addUndefined(S);
// In the assembly for 32 bit x86 the _GLOBAL_OFFSET_TABLE_ symbol
// is magical and is used to produce a R_386_GOTPC relocation.

5
lld/ELF/Writer.cpp
View File

@ -648,9 +648,12 @@ template <class ELFT> void Writer<ELFT>::writeHeader() {
EHdr->e_type = Config->Shared ? ET_DYN : ET_EXEC;
EHdr->e_machine = FirstObj.getEMachine();
EHdr->e_version = EV_CURRENT;
if (Config->EntrySym)
if (Config->EntrySym) {
if (auto *E = dyn_cast<ELFSymbolBody<ELFT>>(Config->EntrySym->repl()))
EHdr->e_entry = getSymVA<ELFT>(*E);
} else if (Config->EntryAddr != uint64_t(-1)) {
EHdr->e_entry = Config->EntryAddr;
}
EHdr->e_phoff = sizeof(Elf_Ehdr);
EHdr->e_shoff = SectionHeaderOff;
EHdr->e_ehsize = sizeof(Elf_Ehdr);

13
lld/test/elf2/entry.s
View File

@ -2,5 +2,16 @@
# RUN: not ld.lld2 %t1 -o %t2
# RUN: ld.lld2 %t1 -o %t2 -e _end
.globl _end;
# RUN: ld.lld2 %t1 -o %t2 -e 4096
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=DEC %s
# RUN: ld.lld2 %t1 -o %t2 -e 0xcafe
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=HEX %s
# RUN: ld.lld2 %t1 -o %t2 -e 0777
# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=OCT %s
# DEC: Entry: 0x1000
# HEX: Entry: 0xCAFE
# OCT: Entry: 0x1FF
.globl _end
_end: