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* target-reloc.h (scan_relocs): Call scan.local for relocs

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against symbols in discarded sections.  Pass is_discarded
	param.
	* arm.cc, * i386.cc, * sparc.cc, * x86_64.cc (Target_*::Scan::local):
	Add is_discarded param.
	* powerpc (Target_powerpc::Scan::local): Likewise.  Use
	is_discarded to flag opd entry as discarded.  Don't emit dyn
	relocs on such entries.
	(Target_powerpc::Scan::global): Similarly detect and handle
	such opd entries.
	(Powerpc_relobj): Replace opd_ent_shndx_ and opd_ent_off_ with
	opd_ent_.  Update all uses.
	(Powerpc_relobj::get_opd_discard, set_opd_discard): New functions.
	(Target_powerpc::relocate_section): Zero out discarded opd
	entry relocs.
This commit is contained in:
Alan Modra 2012-09-12 22:43:54 +00:00
parent 7c0e90d28c
commit bfdfa4cd8d
7 changed files with 209 additions and 78 deletions
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18
gold/ChangeLog
View File

@ -1,3 +1,21 @@
2012-09-13 Alan Modra <amodra@gmail.com>
* target-reloc.h (scan_relocs): Call scan.local for relocs
against symbols in discarded sections. Pass is_discarded
param.
* arm.cc, * i386.cc, * sparc.cc, * x86_64.cc (Target_*::Scan::local):
Add is_discarded param.
* powerpc (Target_powerpc::Scan::local): Likewise. Use
is_discarded to flag opd entry as discarded. Don't emit dyn
relocs on such entries.
(Target_powerpc::Scan::global): Similarly detect and handle
such opd entries.
(Powerpc_relobj): Replace opd_ent_shndx_ and opd_ent_off_ with
opd_ent_. Update all uses.
(Powerpc_relobj::get_opd_discard, set_opd_discard): New functions.
(Target_powerpc::relocate_section): Zero out discarded opd
entry relocs.
2012-09-12 Ian Lance Taylor <iant@google.com>
PR gold/14570

9
gold/arm.cc
View File

@ -2551,7 +2551,8 @@ class Target_arm : public Sized_target<32, big_endian>
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
const elfcpp::Sym<32, big_endian>& lsym);
const elfcpp::Sym<32, big_endian>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_arm* target,
@ -7857,8 +7858,12 @@ Target_arm<big_endian>::Scan::local(Symbol_table* symtab,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, big_endian>& lsym)
const elfcpp::Sym<32, big_endian>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
r_type = get_real_reloc_type(r_type);
switch (r_type)
{

23
gold/i386.cc
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@ -538,7 +538,8 @@ class Target_i386 : public Sized_target<32, false>
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
const elfcpp::Sym<32, false>& lsym);
const elfcpp::Sym<32, false>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_i386* target,
@ -1702,15 +1703,19 @@ Target_i386::Scan::reloc_needs_plt_for_ifunc(
inline void
Target_i386::Scan::local(Symbol_table* symtab,
Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, false>& lsym)
Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, false>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
// A local STT_GNU_IFUNC symbol may require a PLT entry.
if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
&& this->reloc_needs_plt_for_ifunc(object, r_type))

178
gold/powerpc.cc
View File

@ -65,8 +65,7 @@ public:
Powerpc_relobj(const std::string& name, Input_file* input_file, off_t offset,
const typename elfcpp::Ehdr<size, big_endian>& ehdr)
: Sized_relobj_file<size, big_endian>(name, input_file, offset, ehdr),
special_(0), opd_ent_shndx_(), opd_ent_off_(), access_from_map_(),
opd_valid_(false)
special_(0), opd_valid_(false), opd_ent_(), access_from_map_()
{ }
~Powerpc_relobj()
@ -97,8 +96,7 @@ public:
init_opd(size_t opd_size)
{
size_t count = this->opd_ent_ndx(opd_size);
this->opd_ent_shndx_.resize(count);
this->opd_ent_off_.reserve(count);
this->opd_ent_.resize(count);
}
// Return section and offset of function entry for .opd + R_OFF.
@ -106,11 +104,11 @@ public:
get_opd_ent(Address r_off, Address* value = NULL) const
{
size_t ndx = this->opd_ent_ndx(r_off);
gold_assert(ndx < this->opd_ent_shndx_.size());
gold_assert(this->opd_ent_shndx_[ndx] != 0);
gold_assert(ndx < this->opd_ent_.size());
gold_assert(this->opd_ent_[ndx].shndx != 0);
if (value != NULL)
*value = this->opd_ent_off_[ndx];
return this->opd_ent_shndx_[ndx];
*value = this->opd_ent_[ndx].off;
return this->opd_ent_[ndx].shndx;
}
// Set section and offset of function entry for .opd + R_OFF.
@ -118,9 +116,27 @@ public:
set_opd_ent(Address r_off, unsigned int shndx, Address value)
{
size_t ndx = this->opd_ent_ndx(r_off);
gold_assert(ndx < this->opd_ent_shndx_.size());
this->opd_ent_shndx_[ndx] = shndx;
this->opd_ent_off_[ndx] = value;
gold_assert(ndx < this->opd_ent_.size());
this->opd_ent_[ndx].shndx = shndx;
this->opd_ent_[ndx].off = value;
}
// Return discard flag for .opd + R_OFF.
bool
get_opd_discard(Address r_off) const
{
size_t ndx = this->opd_ent_ndx(r_off);
gold_assert(ndx < this->opd_ent_.size());
return this->opd_ent_[ndx].discard;
}
// Set discard flag for .opd + R_OFF.
void
set_opd_discard(Address r_off)
{
size_t ndx = this->opd_ent_ndx(r_off);
gold_assert(ndx < this->opd_ent_.size());
this->opd_ent_[ndx].discard = true;
}
Access_from*
@ -165,38 +181,47 @@ public:
{ return 0x8000; }
private:
// Return index into opd_ent_shndx or opd_ent_off array for .opd entry
// at OFF. .opd entries are 24 bytes long, but they can be spaced
// 16 bytes apart when the language doesn't use the last 8-byte
// word, the environment pointer. Thus dividing the entry section
// offset by 16 will give an index into opd_ent_shndx_ and
// opd_ent_off_ that works for either layout of .opd. (It leaves
// some elements of the vectors unused when .opd entries are spaced
// 24 bytes apart, but we don't know the spacing until relocations
// are processed, and in any case it is possible for an object to
// have some entries spaced 16 bytes apart and others 24 bytes apart.)
struct Opd_ent
{
unsigned int shndx;
bool discard;
Offset off;
};
// Return index into opd_ent_ array for .opd entry at OFF.
// .opd entries are 24 bytes long, but they can be spaced 16 bytes
// apart when the language doesn't use the last 8-byte word, the
// environment pointer. Thus dividing the entry section offset by
// 16 will give an index into opd_ent_ that works for either layout
// of .opd. (It leaves some elements of the vector unused when .opd
// entries are spaced 24 bytes apart, but we don't know the spacing
// until relocations are processed, and in any case it is possible
// for an object to have some entries spaced 16 bytes apart and
// others 24 bytes apart.)
size_t
opd_ent_ndx(size_t off) const
{ return off >> 4;}
// For 32-bit the .got2 section shdnx, for 64-bit the .opd section shndx.
unsigned int special_;
// The first 8-byte word of an OPD entry gives the address of the
// entry point of the function. Relocatable object files have a
// relocation on this word. The following two vectors record the
// section and offset specified by these relocations.
std::vector<unsigned int> opd_ent_shndx_;
std::vector<Offset> opd_ent_off_;
// References made to this object's .opd section when running
// gc_process_relocs for another object, before the opd_ent vectors
// are valid for this object.
Access_from access_from_map_;
// Set at the start of gc_process_relocs, when we know opd_ent
// vectors are valid. The flag could be made atomic and set in
// Set at the start of gc_process_relocs, when we know opd_ent_
// vector is valid. The flag could be made atomic and set in
// do_read_relocs with memory_order_release and then tested with
// memory_order_acquire, potentially resulting in fewer entries in
// access_from_map_.
bool opd_valid_;
// The first 8-byte word of an OPD entry gives the address of the
// entry point of the function. Relocatable object files have a
// relocation on this word. The following vector records the
// section and offset specified by these relocations.
std::vector<Opd_ent> opd_ent_;
// References made to this object's .opd section when running
// gc_process_relocs for another object, before the opd_ent_ vector
// is valid for this object.
Access_from access_from_map_;
};
template<int size, bool big_endian>
@ -413,6 +438,8 @@ class Target_powerpc : public Sized_target<size, big_endian>
class Scan
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
Scan()
: issued_non_pic_error_(false)
{ }
@ -426,7 +453,8 @@ class Target_powerpc : public Sized_target<size, big_endian>
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, big_endian>& reloc, unsigned int r_type,
const elfcpp::Sym<size, big_endian>& lsym);
const elfcpp::Sym<size, big_endian>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_powerpc* target,
@ -2361,11 +2389,21 @@ Target_powerpc<size, big_endian>::Scan::local(
Output_section* output_section,
const elfcpp::Rela<size, big_endian>& reloc,
unsigned int r_type,
const elfcpp::Sym<size, big_endian>& /* lsym */)
const elfcpp::Sym<size, big_endian>& /* lsym */,
bool is_discarded)
{
Powerpc_relobj<size, big_endian>* ppc_object
= static_cast<Powerpc_relobj<size, big_endian>*>(object);
if (is_discarded)
{
if (size == 64
&& data_shndx == ppc_object->opd_shndx()
&& r_type == elfcpp::R_PPC64_ADDR64)
ppc_object->set_opd_discard(reloc.get_r_offset());
return;
}
switch (r_type)
{
case elfcpp::R_POWERPC_NONE:
@ -2382,13 +2420,19 @@ Target_powerpc<size, big_endian>::Scan::local(
= target->got_section(symtab, layout);
if (parameters->options().output_is_position_independent())
{
Address off = reloc.get_r_offset();
if (size == 64
&& data_shndx == ppc_object->opd_shndx()
&& ppc_object->get_opd_discard(off - 8))
break;
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
Powerpc_relobj<size, big_endian>* symobj = ppc_object;
rela_dyn->add_output_section_relative(got->output_section(),
elfcpp::R_POWERPC_RELATIVE,
output_section,
object, data_shndx,
reloc.get_r_offset(),
ppc_object->toc_base_offset());
object, data_shndx, off,
symobj->toc_base_offset());
}
}
break;
@ -2658,6 +2702,12 @@ Target_powerpc<size, big_endian>::Scan::global(
= target->got_section(symtab, layout);
if (parameters->options().output_is_position_independent())
{
Address off = reloc.get_r_offset();
if (size == 64
&& data_shndx == ppc_object->opd_shndx()
&& ppc_object->get_opd_discard(off - 8))
break;
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
Powerpc_relobj<size, big_endian>* symobj = ppc_object;
if (data_shndx != ppc_object->opd_shndx())
@ -2666,14 +2716,22 @@ Target_powerpc<size, big_endian>::Scan::global(
rela_dyn->add_output_section_relative(got->output_section(),
elfcpp::R_POWERPC_RELATIVE,
output_section,
object, data_shndx,
reloc.get_r_offset(),
object, data_shndx, off,
symobj->toc_base_offset());
}
}
break;
case elfcpp::R_PPC64_ADDR64:
if (size == 64
&& data_shndx == ppc_object->opd_shndx()
&& (gsym->is_defined_in_discarded_section()
|| gsym->object() != object))
{
ppc_object->set_opd_discard(reloc.get_r_offset());
break;
}
// Fall thru
case elfcpp::R_PPC64_UADDR64:
case elfcpp::R_POWERPC_ADDR32:
case elfcpp::R_POWERPC_UADDR32:
@ -4038,6 +4096,43 @@ Target_powerpc<size, big_endian>::relocate_section(
gold_assert(sh_type == elfcpp::SHT_RELA);
unsigned char *opd_rel = NULL;
Powerpc_relobj<size, big_endian>* const object
= static_cast<Powerpc_relobj<size, big_endian>*>(relinfo->object);
if (size == 64
&& relinfo->data_shndx == object->opd_shndx())
{
// Rewrite opd relocs, omitting those for discarded sections
// to silence gold::relocate_section errors.
const int reloc_size
= Reloc_types<elfcpp::SHT_RELA, size, big_endian>::reloc_size;
opd_rel = new unsigned char[reloc_count * reloc_size];
const unsigned char* rrel = prelocs;
unsigned char* wrel = opd_rel;
for (size_t i = 0;
i < reloc_count;
++i, rrel += reloc_size, wrel += reloc_size)
{
typename Reloc_types<elfcpp::SHT_RELA, size, big_endian>::Reloc
reloc(rrel);
typename elfcpp::Elf_types<size>::Elf_WXword r_info
= reloc.get_r_info();
unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
Address r_off = reloc.get_r_offset();
if (r_type == elfcpp::R_PPC64_TOC)
r_off -= 8;
bool is_discarded = object->get_opd_discard(r_off);
// Reloc number is reported in some errors, so keep all relocs.
if (is_discarded)
memset(wrel, 0, reloc_size);
else
memcpy(wrel, rrel, reloc_size);
}
prelocs = opd_rel;
}
gold::relocate_section<size, big_endian, Powerpc, elfcpp::SHT_RELA,
Powerpc_relocate>(
relinfo,
@ -4050,6 +4145,9 @@ Target_powerpc<size, big_endian>::relocate_section(
address,
view_size,
reloc_symbol_changes);
if (opd_rel != NULL)
delete[] opd_rel;
}
class Powerpc_scan_relocatable_reloc

9
gold/sparc.cc
View File

@ -237,7 +237,8 @@ class Target_sparc : public Sized_target<size, big_endian>
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, big_endian>& reloc, unsigned int r_type,
const elfcpp::Sym<size, big_endian>& lsym);
const elfcpp::Sym<size, big_endian>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_sparc* target,
@ -2240,8 +2241,12 @@ Target_sparc<size, big_endian>::Scan::local(
Output_section* output_section,
const elfcpp::Rela<size, big_endian>& reloc,
unsigned int r_type,
const elfcpp::Sym<size, big_endian>& lsym)
const elfcpp::Sym<size, big_endian>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
bool is_ifunc = lsym.get_st_type() == elfcpp::STT_GNU_IFUNC;
unsigned int orig_r_type = r_type;
r_type &= 0xff;

41
gold/target-reloc.h
View File

@ -81,30 +81,25 @@ scan_relocs(
unsigned int shndx = lsym.get_st_shndx();
bool is_ordinary;
shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
if (is_ordinary
&& shndx != elfcpp::SHN_UNDEF
&& !object->is_section_included(shndx)
&& !symtab->is_section_folded(object, shndx))
{
// RELOC is a relocation against a local symbol in a
// section we are discarding. We can ignore this
// relocation. It will eventually become a reloc
// against the value zero.
//
// FIXME: We should issue a warning if this is an
// allocated section; is this the best place to do it?
//
// FIXME: The old GNU linker would in some cases look
// for the linkonce section which caused this section to
// be discarded, and, if the other section was the same
// size, change the reloc to refer to the other section.
// That seems risky and weird to me, and I don't know of
// any case where it is actually required.
continue;
}
// If RELOC is a relocation against a local symbol in a
// section we are discarding then we can ignore it. It will
// eventually become a reloc against the value zero.
//
// FIXME: We should issue a warning if this is an
// allocated section; is this the best place to do it?
//
// FIXME: The old GNU linker would in some cases look
// for the linkonce section which caused this section to
// be discarded, and, if the other section was the same
// size, change the reloc to refer to the other section.
// That seems risky and weird to me, and I don't know of
// any case where it is actually required.
bool is_discarded = (is_ordinary
&& shndx != elfcpp::SHN_UNDEF
&& !object->is_section_included(shndx)
&& !symtab->is_section_folded(object, shndx));
scan.local(symtab, layout, target, object, data_shndx,
output_section, reloc, r_type, lsym);
output_section, reloc, r_type, lsym, is_discarded);
}
else
{

9
gold/x86_64.cc
View File

@ -676,7 +676,8 @@ class Target_x86_64 : public Sized_target<size, false>
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc, unsigned int r_type,
const elfcpp::Sym<size, false>& lsym);
const elfcpp::Sym<size, false>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_x86_64* target,
@ -2270,8 +2271,12 @@ Target_x86_64<size>::Scan::local(Symbol_table* symtab,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<size, false>& lsym)
const elfcpp::Sym<size, false>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
// A local STT_GNU_IFUNC symbol may require a PLT entry.
bool is_ifunc = lsym.get_st_type() == elfcpp::STT_GNU_IFUNC;
if (is_ifunc && this->reloc_needs_plt_for_ifunc(object, r_type))