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Always create a PT_ARM_EXIDX if needed. 

Unfortunatelly PT_ARM_EXIDX is special. There is no way to create it
from linker scripts, so we have to create it even if PHDRS is used.

This matches bfd and is required for the lld output to survive bfd's strip.

llvm-svn: 288012
This commit is contained in:
Rafael Espindola 2016-11-28 00:40:21 +00:00
parent 17786f77f0
commit 8e67000f1a
2 changed files with 34 additions and 7 deletions
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25
lld/ELF/Writer.cpp
View File

@ -60,6 +60,7 @@ private:
void addPredefinedSections();
std::vector<Phdr> createPhdrs();
void addPtArmExid(std::vector<Phdr> &Phdrs);
void assignAddresses();
void assignFileOffsets();
void assignFileOffsetsBinary();
@ -181,6 +182,7 @@ template <class ELFT> void Writer<ELFT>::run() {
} else {
Phdrs = Script<ELFT>::X->hasPhdrsCommands() ? Script<ELFT>::X->createPhdrs()
: createPhdrs();
addPtArmExid(Phdrs);
fixHeaders();
if (ScriptConfig->HasSections) {
Script<ELFT>::X->assignAddresses(Phdrs);
@ -1129,7 +1131,6 @@ template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
Phdr TlsHdr(PT_TLS, PF_R);
Phdr RelRo(PT_GNU_RELRO, PF_R);
Phdr Note(PT_NOTE, PF_R);
Phdr ARMExidx(PT_ARM_EXIDX, PF_R);
for (OutputSectionBase *Sec : OutputSections) {
if (!(Sec->Flags & SHF_ALLOC))
break;
@ -1160,8 +1161,6 @@ template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
RelRo.add(Sec);
if (Sec->Type == SHT_NOTE)
Note.add(Sec);
if (Config->EMachine == EM_ARM && Sec->Type == SHT_ARM_EXIDX)
ARMExidx.add(Sec);
}
// Add the TLS segment unless it's empty.
@ -1194,10 +1193,6 @@ template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
Hdr.add(Sec);
}
// PT_ARM_EXIDX is the ARM EHABI equivalent of PT_GNU_EH_FRAME
if (ARMExidx.First)
Ret.push_back(std::move(ARMExidx));
// PT_GNU_STACK is a special section to tell the loader to make the
// pages for the stack non-executable.
if (!Config->ZExecstack) {
@ -1218,6 +1213,22 @@ template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
return Ret;
}
template <class ELFT>
void Writer<ELFT>::addPtArmExid(std::vector<PhdrEntry<ELFT>> &Phdrs) {
if (Config->EMachine != EM_ARM)
return;
auto I = std::find_if(
OutputSections.begin(), OutputSections.end(),
[](OutputSectionBase *Sec) { return Sec->Type == SHT_ARM_EXIDX; });
if (I == OutputSections.end())
return;
// PT_ARM_EXIDX is the ARM EHABI equivalent of PT_GNU_EH_FRAME
Phdr ARMExidx(PT_ARM_EXIDX, PF_R);
ARMExidx.add(*I);
Phdrs.push_back(ARMExidx);
}
// The first section of each PT_LOAD and the first section after PT_GNU_RELRO
// have to be page aligned so that the dynamic linker can set the permissions.
template <class ELFT> void Writer<ELFT>::fixSectionAlignments() {

16
lld/test/ELF/linkerscript/arm-exidx-phdrs.s Normal file
View File

@ -0,0 +1,16 @@
// REQUIRES: arm
// RUN: llvm-mc -filetype=obj -triple=armv7a-none-linux-gnueabi %s -o %t.o
// RUN: echo "PHDRS { ph_text PT_LOAD; } \
// RUN: SECTIONS { \
// RUN: . = SIZEOF_HEADERS; \
// RUN: .text : { *(.text) } : ph_text \
// RUN: }" > %t.script
// RUN: ld.lld -T %t.script %t.o -shared -o %t.so
// RUN: llvm-readobj --program-headers %t.so | FileCheck %s
// CHECK: Type: PT_ARM_EXIDX
.fnstart
bx lr
.cantunwind
.fnend