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ELF: Omit PT_GNU_STACK segment if -z execstack is provided.

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In the previous patch (r254003), I made the linker emit PT_GNU_STACK
unconditionally. But sometimes you want to have a control over the
presence of the segment. With this patch, you can omit the segment
by passing -z execstack option.

llvm-svn: 254039
This commit is contained in:
Rui Ueyama
2015-11-24 23:42:33 +00:00
parent 28b700373e
commit a46566f2db
2 changed files with 28 additions and 43 deletions
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13
lld/ELF/Writer.cpp
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@@ -933,12 +933,11 @@ template <class ELFT> void Writer<ELFT>::assignAddresses() {
// PT_GNU_STACK is a special section to tell the loader to make the
// pages for the stack non-executable.
Elf_Phdr *PH = &Phdrs[++PhdrIdx];
PH->p_type = PT_GNU_STACK;
if (Config->ZExecStack)
PH->p_flags = PF_R | PF_W | PF_X;
else
if (!Config->ZExecStack) {
Elf_Phdr *PH = &Phdrs[++PhdrIdx];
PH->p_type = PT_GNU_STACK;
PH->p_flags = PF_R | PF_W;
}
// Fix up PT_INTERP as we now know the address of .interp section.
if (Interp) {
@@ -962,11 +961,13 @@ template <class ELFT> void Writer<ELFT>::assignAddresses() {
// Returns the number of PHDR entries.
template <class ELFT> int Writer<ELFT>::getPhdrsNum() const {
bool Tls = false;
int I = 3; // 3 for PT_PHDR, first PT_LOAD and PT_GNU_STACK
int I = 2; // 2 for PT_PHDR and first PT_LOAD
if (needsInterpSection())
++I;
if (isOutputDynamic())
++I;
if (!Config->ZExecStack)
++I;
uintX_t Last = PF_R;
for (OutputSectionBase<ELFT> *Sec : OutputSections) {
if (!needsPhdr<ELFT>(Sec))