ports/devel/llvm/17/patches/patch-lld_ELF_Writer_cpp

122 lines
4.5 KiB
Text

Index: lld/ELF/Writer.cpp
--- lld/ELF/Writer.cpp.orig
+++ lld/ELF/Writer.cpp
@@ -243,6 +243,7 @@ void elf::addReservedSymbols() {
};
ElfSym::bss = add("__bss_start", 0);
+ ElfSym::data = add("__data_start", 0);
ElfSym::end1 = add("end", -1);
ElfSym::end2 = add("_end", -1);
ElfSym::etext1 = add("etext", -1);
@@ -494,6 +495,12 @@ template <class ELFT> void elf::createSyntheticSection
in.ibtPlt = std::make_unique<IBTPltSection>();
add(*in.ibtPlt);
}
+#ifdef __OpenBSD__
+ else if (config->emachine == EM_X86_64) {
+ in.ibtPlt = std::make_unique<IBTPltSection>();
+ add(*in.ibtPlt);
+ }
+#endif
if (config->emachine == EM_PPC)
in.plt = std::make_unique<PPC32GlinkSection>();
@@ -665,7 +672,7 @@ static bool shouldKeepInSymtab(const Defined &sym) {
// * --discard-locals is used.
// * The symbol is in a SHF_MERGE section, which is normally the reason for
// the assembler keeping the .L symbol.
- if (sym.getName().starts_with(".L") &&
+ if ((sym.getName().startswith(".L") || sym.getName().empty()) &&
(config->discard == DiscardPolicy::Locals ||
(sym.section && (sym.section->flags & SHF_MERGE))))
return false;
@@ -811,7 +818,11 @@ static bool isRelroSection(const OutputSection *sec) {
// However, if "-z now" is given, the lazy symbol resolution is
// disabled, which enables us to put it into RELRO.
if (sec == in.gotPlt->getParent())
+#ifndef __OpenBSD__
return config->zNow;
+#else
+ return true; /* kbind(2) means we can always put these in RELRO */
+#endif
// .dynamic section contains data for the dynamic linker, and
// there's no need to write to it at runtime, so it's better to put
@@ -1083,6 +1094,9 @@ template <class ELFT> void Writer<ELFT>::setReservedSy
ElfSym::bss->section = sbss ? sbss : findSection(".bss");
}
+ if (ElfSym::data)
+ ElfSym::data->section = findSection(".data");
+
// Setup MIPS _gp_disp/__gnu_local_gp symbols which should
// be equal to the _gp symbol's value.
if (ElfSym::mipsGp) {
@@ -2398,11 +2412,22 @@ SmallVector<PhdrEntry *, 0> Writer<ELFT>::createPhdrs(
addHdr(PT_GNU_EH_FRAME, part.ehFrameHdr->getParent()->getPhdrFlags())
->add(part.ehFrameHdr->getParent());
+ // PT_OPENBSD_MUTABLE is an OpenBSD-specific feature. That makes
+ // the dynamic linker fill the segment with zero data, like bss, but
+ // it can be treated differently.
+ if (OutputSection *cmd = findSection(".openbsd.mutable", partNo))
+ addHdr(PT_OPENBSD_MUTABLE, cmd->getPhdrFlags())->add(cmd);
+
// PT_OPENBSD_RANDOMIZE is an OpenBSD-specific feature. That makes
// the dynamic linker fill the segment with random data.
if (OutputSection *cmd = findSection(".openbsd.randomdata", partNo))
addHdr(PT_OPENBSD_RANDOMIZE, cmd->getPhdrFlags())->add(cmd);
+ // PT_OPENBSD_SYSCALLS is an OpenBSD-specific feature. That makes
+ // the kernel and dynamic linker register system call sites.
+ if (OutputSection *cmd = findSection(".openbsd.syscalls", partNo))
+ addHdr(PT_OPENBSD_SYSCALLS, cmd->getPhdrFlags())->add(cmd);
+
if (config->zGnustack != GnuStackKind::None) {
// PT_GNU_STACK is a special section to tell the loader to make the
// pages for the stack non-executable. If you really want an executable
@@ -2421,6 +2446,11 @@ SmallVector<PhdrEntry *, 0> Writer<ELFT>::createPhdrs(
if (config->zWxneeded)
addHdr(PT_OPENBSD_WXNEEDED, PF_X);
+ // PT_OPENBSD_NOBTCFI is an OpenBSD-specific header to mark that the
+ // executable is expected to violate branch-target CFI checks.
+ if (config->zNoBtCfi)
+ addHdr(PT_OPENBSD_NOBTCFI, PF_X);
+
if (OutputSection *cmd = findSection(".note.gnu.property", partNo))
addHdr(PT_GNU_PROPERTY, PF_R)->add(cmd);
@@ -2513,6 +2543,31 @@ template <class ELFT> void Writer<ELFT>::fixSectionAli
};
}
};
+
+#ifdef __OpenBSD__
+ // On i386, produce binaries that are compatible with our W^X implementation
+ if (config->emachine == EM_386) {
+ auto NXAlign = [](OutputSection *Cmd) {
+ if (Cmd && !Cmd->addrExpr)
+ Cmd->addrExpr = [=] {
+ return alignTo(script->getDot(), 0x20000000);
+ };
+ };
+
+ for (Partition &part : partitions) {
+ PhdrEntry *firstRW = nullptr;
+ for (PhdrEntry *P : part.phdrs) {
+ if (P->p_type == PT_LOAD && (P->p_flags & PF_W)) {
+ firstRW = P;
+ break;
+ }
+ }
+
+ if (firstRW)
+ NXAlign(firstRW->firstSec);
+ }
+ }
+#endif
for (Partition &part : partitions) {
prev = nullptr;