mirror/binutils-gdb
2
0
Fork 0
mirror of https://sourceware.org/git/binutils-gdb.git synced 2024-11-27 03:51:15 +08:00
Code Issues Packages Projects Releases Wiki Activity

2010-01-13 Doug Kwan <dougkwan@google.com>

Browse Source 
* arm.cc (Arm_relobj::section_needs_reloc_stub_scanning,
	Arm_relobj::section_needs_cortex_a8_stub_scanning,
	Arm_relobj::scan_section_for_cortex_a8_erratum,
	Arm_relobj::scan_span_for_cortex_a8_erratum): New methods.
	(Arm_relobj::scan_sections_for_stubs): Move code deciding what
	sections to scan for relocation stubs into a new method
	Arm_relobj::section_needs_reloc_stub_scanning.  Handle both
	relocation and Cortex-A8 stub scanning.
	(Target_arm::do_relax): Force stubs to be after stubbed sections
	if fixing the Cortex-A8 erratum.  Remove all Cortex-A8 stubs at
	the beginning of a new relaxation pass.  Update a comment.
	(Target_arm::scan_span_for_cortex_a8_erratum): New method definition.
This commit is contained in:
Doug Kwan 2010-01-13 21:36:47 +00:00
parent 44b71ece3c
commit 4427219284
2 changed files with 437 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
gold/ChangeLog
View File

@ -1,3 +1,18 @@
2010-01-13 Doug Kwan <dougkwan@google.com>
* arm.cc (Arm_relobj::section_needs_reloc_stub_scanning,
Arm_relobj::section_needs_cortex_a8_stub_scanning,
Arm_relobj::scan_section_for_cortex_a8_erratum,
Arm_relobj::scan_span_for_cortex_a8_erratum): New methods.
(Arm_relobj::scan_sections_for_stubs): Move code deciding what
sections to scan for relocation stubs into a new method
Arm_relobj::section_needs_reloc_stub_scanning. Handle both
relocation and Cortex-A8 stub scanning.
(Target_arm::do_relax): Force stubs to be after stubbed sections
if fixing the Cortex-A8 erratum. Remove all Cortex-A8 stubs at
the beginning of a new relaxation pass. Update a comment.
(Target_arm::scan_span_for_cortex_a8_erratum): New method definition.
2010-01-12 Ian Lance Taylor <iant@google.com>
* target-reloc.h (visibility_error): New inline function.

497
gold/arm.cc
View File

@ -1204,6 +1204,25 @@ class Arm_relobj : public Sized_relobj<32, big_endian>
do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*);
private:
// Whether a section needs to be scanned for relocation stubs.
bool
section_needs_reloc_stub_scanning(const elfcpp::Shdr<32, big_endian>&,
const Relobj::Output_sections&,
const Symbol_table *);
// Whether a section needs to be scanned for the Cortex-A8 erratum.
bool
section_needs_cortex_a8_stub_scanning(const elfcpp::Shdr<32, big_endian>&,
unsigned int, Output_section*,
const Symbol_table *);
// Scan a section for the Cortex-A8 erratum.
void
scan_section_for_cortex_a8_erratum(const elfcpp::Shdr<32, big_endian>&,
unsigned int, Output_section*,
Target_arm<big_endian>*);
// List of stub tables.
typedef std::vector<Stub_table<big_endian>*> Stub_table_list;
Stub_table_list stub_tables_;
@ -1661,6 +1680,12 @@ class Target_arm : public Sized_target<32, big_endian>
fix_cortex_a8() const
{ return this->fix_cortex_a8_; }
// Scan a span of THUMB code section for Cortex-A8 erratum.
void
scan_span_for_cortex_a8_erratum(Arm_relobj<big_endian>*, unsigned int,
section_size_type, section_size_type,
const unsigned char*, Arm_address);
protected:
// Make an ELF object.
Object*
@ -4142,6 +4167,155 @@ Arm_output_section<big_endian>::group_sections(
// Arm_relobj methods.
// Determine if we want to scan the SHNDX-th section for relocation stubs.
// This is a helper for Arm_relobj::scan_sections_for_stubs() below.
template<bool big_endian>
bool
Arm_relobj<big_endian>::section_needs_reloc_stub_scanning(
const elfcpp::Shdr<32, big_endian>& shdr,
const Relobj::Output_sections& out_sections,
const Symbol_table *symtab)
{
unsigned int sh_type = shdr.get_sh_type();
if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
return false;
// Ignore empty section.
off_t sh_size = shdr.get_sh_size();
if (sh_size == 0)
return false;
// Ignore reloc section with bad info. This error will be
// reported in the final link.
unsigned int index = this->adjust_shndx(shdr.get_sh_info());
if (index >= this->shnum())
return false;
// This relocation section is against a section which we
// discarded or if the section is folded into another
// section due to ICF.
if (out_sections[index] == NULL || symtab->is_section_folded(this, index))
return false;
// Ignore reloc section with unexpected symbol table. The
// error will be reported in the final link.
if (this->adjust_shndx(shdr.get_sh_link()) != this->symtab_shndx())
return false;
const unsigned int reloc_size = (sh_type == elfcpp::SHT_REL
? elfcpp::Elf_sizes<32>::rel_size
: elfcpp::Elf_sizes<32>::rela_size);
// Ignore reloc section with unexpected entsize or uneven size.
// The error will be reported in the final link.
if (reloc_size != shdr.get_sh_entsize() || sh_size % reloc_size != 0)
return false;
return true;
}
// Determine if we want to scan the SHNDX-th section for non-relocation stubs.
// This is a helper for Arm_relobj::scan_sections_for_stubs() below.
template<bool big_endian>
bool
Arm_relobj<big_endian>::section_needs_cortex_a8_stub_scanning(
const elfcpp::Shdr<32, big_endian>& shdr,
unsigned int shndx,
Output_section* os,
const Symbol_table* symtab)
{
// We only scan non-empty code sections.
if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) == 0
|| shdr.get_sh_size() == 0)
return false;
// Ignore discarded or ICF'ed sections.
if (os == NULL || symtab->is_section_folded(this, shndx))
return false;
// Find output address of section.
Arm_address address = os->output_address(this, shndx, 0);
// If the section does not cross any 4K-boundaries, it does not need to
// be scanned.
if ((address & ~0xfffU) == ((address + shdr.get_sh_size() - 1) & ~0xfffU))
return false;
return true;
}
// Scan a section for Cortex-A8 workaround.
template<bool big_endian>
void
Arm_relobj<big_endian>::scan_section_for_cortex_a8_erratum(
const elfcpp::Shdr<32, big_endian>& shdr,
unsigned int shndx,
Output_section* os,
Target_arm<big_endian>* arm_target)
{
Arm_address output_address = os->output_address(this, shndx, 0);
// Get the section contents.
section_size_type input_view_size = 0;
const unsigned char* input_view =
this->section_contents(shndx, &input_view_size, false);
// We need to go through the mapping symbols to determine what to
// scan. There are two reasons. First, we should look at THUMB code and
// THUMB code only. Second, we only want to look at the 4K-page boundary
// to speed up the scanning.
// Look for the first mapping symbol in this section. It should be
// at (shndx, 0).
Mapping_symbol_position section_start(shndx, 0);
typename Mapping_symbols_info::const_iterator p =
this->mapping_symbols_info_.lower_bound(section_start);
if (p == this->mapping_symbols_info_.end()
|| p->first != section_start)
{
gold_warning(_("Cortex-A8 erratum scanning failed because there "
"is no mapping symbols for section %u of %s"),
shndx, this->name().c_str());
return;
}
while (p != this->mapping_symbols_info_.end()
&& p->first.first == shndx)
{
typename Mapping_symbols_info::const_iterator next =
this->mapping_symbols_info_.upper_bound(p->first);
// Only scan part of a section with THUMB code.
if (p->second == 't')
{
// Determine the end of this range.
section_size_type span_start =
convert_to_section_size_type(p->first.second);
section_size_type span_end;
if (next != this->mapping_symbols_info_.end()
&& next->first.first == shndx)
span_end = convert_to_section_size_type(next->first.second);
else
span_end = convert_to_section_size_type(shdr.get_sh_size());
if (((span_start + output_address) & ~0xfffUL)
!= ((span_end + output_address - 1) & ~0xfffUL))
{
arm_target->scan_span_for_cortex_a8_erratum(this, shndx,
span_start, span_end,
input_view,
output_address);
}
}
p = next;
}
}
// Scan relocations for stub generation.
template<bool big_endian>
@ -4170,87 +4344,73 @@ Arm_relobj<big_endian>::scan_sections_for_stubs(
relinfo.layout = layout;
relinfo.object = this;
// Do relocation stubs scanning.
const unsigned char* p = pshdrs + shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += shdr_size)
{
typename elfcpp::Shdr<32, big_endian> shdr(p);
unsigned int sh_type = shdr.get_sh_type();
if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
continue;
off_t sh_size = shdr.get_sh_size();
if (sh_size == 0)
continue;
unsigned int index = this->adjust_shndx(shdr.get_sh_info());
if (index >= this->shnum())
const elfcpp::Shdr<32, big_endian> shdr(p);
if (this->section_needs_reloc_stub_scanning(shdr, out_sections, symtab))
{
// Ignore reloc section with bad info. This error will be
// reported in the final link.
continue;
}
unsigned int index = this->adjust_shndx(shdr.get_sh_info());
Arm_address output_offset = this->get_output_section_offset(index);
Arm_address output_address;
if(output_offset != invalid_address)
output_address = out_sections[index]->address() + output_offset;
else
{
// Currently this only happens for a relaxed section.
const Output_relaxed_input_section* poris =
out_sections[index]->find_relaxed_input_section(this, index);
gold_assert(poris != NULL);
output_address = poris->address();
}
Output_section* os = out_sections[index];
if (os == NULL
|| symtab->is_section_folded(this, index))
// Get the relocations.
const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
shdr.get_sh_size(),
true, false);
// Get the section contents. This does work for the case in which
// we modify the contents of an input section. We need to pass the
// output view under such circumstances.
section_size_type input_view_size = 0;
const unsigned char* input_view =
this->section_contents(index, &input_view_size, false);
relinfo.reloc_shndx = i;
relinfo.data_shndx = index;
unsigned int sh_type = shdr.get_sh_type();
const unsigned int reloc_size = (sh_type == elfcpp::SHT_REL
? elfcpp::Elf_sizes<32>::rel_size
: elfcpp::Elf_sizes<32>::rela_size);
Output_section* os = out_sections[index];
arm_target->scan_section_for_stubs(&relinfo, sh_type, prelocs,
shdr.get_sh_size() / reloc_size,
os,
output_offset == invalid_address,
input_view, output_address,
input_view_size);
}
}
// Do Cortex-A8 erratum stubs scanning. This has to be done for a section
// after its relocation section, if there is one, is processed for
// relocation stubs. Merging this loop with the one above would have been
// complicated since we would have had to make sure that relocation stub
// scanning is done first.
if (arm_target->fix_cortex_a8())
{
const unsigned char* p = pshdrs + shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += shdr_size)
{
// This relocation section is against a section which we
// discarded or if the section is folded into another
// section due to ICF.
continue;
const elfcpp::Shdr<32, big_endian> shdr(p);
if (this->section_needs_cortex_a8_stub_scanning(shdr, i,
out_sections[i],
symtab))
this->scan_section_for_cortex_a8_erratum(shdr, i, out_sections[i],
arm_target);
}
Arm_address output_offset = this->get_output_section_offset(index);
if (this->adjust_shndx(shdr.get_sh_link()) != this->symtab_shndx())
{
// Ignore reloc section with unexpected symbol table. The
// error will be reported in the final link.
continue;
}
const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
sh_size, true, false);
unsigned int reloc_size;
if (sh_type == elfcpp::SHT_REL)
reloc_size = elfcpp::Elf_sizes<32>::rel_size;
else
reloc_size = elfcpp::Elf_sizes<32>::rela_size;
if (reloc_size != shdr.get_sh_entsize())
{
// Ignore reloc section with unexpected entsize. The error
// will be reported in the final link.
continue;
}
size_t reloc_count = sh_size / reloc_size;
if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
{
// Ignore reloc section with uneven size. The error will be
// reported in the final link.
continue;
}
gold_assert(output_offset != invalid_address
|| this->relocs_must_follow_section_writes());
// Get the section contents. This does work for the case in which
// we modify the contents of an input section. We need to pass the
// output view under such circumstances.
section_size_type input_view_size = 0;
const unsigned char* input_view =
this->section_contents(index, &input_view_size, false);
relinfo.reloc_shndx = i;
relinfo.data_shndx = index;
arm_target->scan_section_for_stubs(&relinfo, sh_type, prelocs,
reloc_count, os,
output_offset == invalid_address,
input_view,
os->address(),
input_view_size);
}
// After we've done the relocations, we release the hash tables,
@ -7444,6 +7604,12 @@ Target_arm<big_endian>::do_relax(
bool stubs_always_after_branch = stub_group_size_param < 0;
section_size_type stub_group_size = abs(stub_group_size_param);
// The Cortex-A8 erratum fix depends on stubs not being in the same 4K
// page as the first half of a 32-bit branch straddling two 4K pages.
// This is a crude way of enforcing that.
if (this->fix_cortex_a8_)
stubs_always_after_branch = true;
if (stub_group_size == 1)
{
// Default value.
@ -7461,6 +7627,11 @@ Target_arm<big_endian>::do_relax(
group_sections(layout, stub_group_size, stubs_always_after_branch);
}
// The Cortex-A8 stubs are sensitive to layout of code sections. At the
// beginning of each relaxation pass, just blow away all the stubs.
// Alternatively, we could selectively remove only the stubs and reloc
// information for code sections that have moved since the last pass.
// That would require more book-keeping.
typedef typename Stub_table_list::iterator Stub_table_iterator;
if (this->fix_cortex_a8_)
{
@ -7471,9 +7642,15 @@ Target_arm<big_endian>::do_relax(
++p)
delete p->second;
this->cortex_a8_relocs_info_.clear();
// Remove all Cortex-A8 stubs.
for (Stub_table_iterator sp = this->stub_tables_.begin();
sp != this->stub_tables_.end();
++sp)
(*sp)->remove_all_cortex_a8_stubs();
}
// scan relocs for stubs
// Scan relocs for relocation stubs
for (Input_objects::Relobj_iterator op = input_objects->relobj_begin();
op != input_objects->relobj_end();
++op)
@ -7598,6 +7775,176 @@ Target_arm<big_endian>::do_attributes_order(int num) const
return num;
}
// Scan a span of THUMB code for Cortex-A8 erratum.
template<bool big_endian>
void
Target_arm<big_endian>::scan_span_for_cortex_a8_erratum(
Arm_relobj<big_endian>* arm_relobj,
unsigned int shndx,
section_size_type span_start,
section_size_type span_end,
const unsigned char* view,
Arm_address address)
{
// Scan for 32-bit Thumb-2 branches which span two 4K regions, where:
//
// The opcode is BLX.W, BL.W, B.W, Bcc.W
// The branch target is in the same 4KB region as the
// first half of the branch.
// The instruction before the branch is a 32-bit
// length non-branch instruction.
section_size_type i = span_start;
bool last_was_32bit = false;
bool last_was_branch = false;
while (i < span_end)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
const Valtype* wv = reinterpret_cast<const Valtype*>(view + i);
uint32_t insn = elfcpp::Swap<16, big_endian>::readval(wv);
bool is_blx = false, is_b = false;
bool is_bl = false, is_bcc = false;
bool insn_32bit = (insn & 0xe000) == 0xe000 && (insn & 0x1800) != 0x0000;
if (insn_32bit)
{
// Load the rest of the insn (in manual-friendly order).
insn = (insn << 16) | elfcpp::Swap<16, big_endian>::readval(wv + 1);
// Encoding T4: B<c>.W.
is_b = (insn & 0xf800d000U) == 0xf0009000U;
// Encoding T1: BL<c>.W.
is_bl = (insn & 0xf800d000U) == 0xf000d000U;
// Encoding T2: BLX<c>.W.
is_blx = (insn & 0xf800d000U) == 0xf000c000U;
// Encoding T3: B<c>.W (not permitted in IT block).
is_bcc = ((insn & 0xf800d000U) == 0xf0008000U
&& (insn & 0x07f00000U) != 0x03800000U);
}
bool is_32bit_branch = is_b || is_bl || is_blx || is_bcc;
// If this instruction is a 32-bit THUMB branch that crosses a 4K
// page boundary and it follows 32-bit non-branch instruction,
// we need to work around.
if (is_32bit_branch
&& ((address + i) & 0xfffU) == 0xffeU
&& last_was_32bit
&& !last_was_branch)
{
// Check to see if there is a relocation stub for this branch.
bool force_target_arm = false;
bool force_target_thumb = false;
const Cortex_a8_reloc* cortex_a8_reloc = NULL;
Cortex_a8_relocs_info::const_iterator p =
this->cortex_a8_relocs_info_.find(address + i);
if (p != this->cortex_a8_relocs_info_.end())
{
cortex_a8_reloc = p->second;
bool target_is_thumb = (cortex_a8_reloc->destination() & 1) != 0;
if (cortex_a8_reloc->r_type() == elfcpp::R_ARM_THM_CALL
&& !target_is_thumb)
force_target_arm = true;
else if (cortex_a8_reloc->r_type() == elfcpp::R_ARM_THM_CALL
&& target_is_thumb)
force_target_thumb = true;
}
off_t offset;
Stub_type stub_type = arm_stub_none;
// Check if we have an offending branch instruction.
uint16_t upper_insn = (insn >> 16) & 0xffffU;
uint16_t lower_insn = insn & 0xffffU;
typedef struct Arm_relocate_functions<big_endian> RelocFuncs;
if (cortex_a8_reloc != NULL
&& cortex_a8_reloc->reloc_stub() != NULL)
// We've already made a stub for this instruction, e.g.
// it's a long branch or a Thumb->ARM stub. Assume that
// stub will suffice to work around the A8 erratum (see
// setting of always_after_branch above).
;
else if (is_bcc)
{
offset = RelocFuncs::thumb32_cond_branch_offset(upper_insn,
lower_insn);
stub_type = arm_stub_a8_veneer_b_cond;
}
else if (is_b || is_bl || is_blx)
{
offset = RelocFuncs::thumb32_branch_offset(upper_insn,
lower_insn);
if (is_blx)
offset &= ~3;
stub_type = (is_blx
? arm_stub_a8_veneer_blx
: (is_bl
? arm_stub_a8_veneer_bl
: arm_stub_a8_veneer_b));
}
if (stub_type != arm_stub_none)
{
Arm_address pc_for_insn = address + i + 4;
// The original instruction is a BL, but the target is
// an ARM instruction. If we were not making a stub,
// the BL would have been converted to a BLX. Use the
// BLX stub instead in that case.
if (this->may_use_blx() && force_target_arm
&& stub_type == arm_stub_a8_veneer_bl)
{
stub_type = arm_stub_a8_veneer_blx;
is_blx = true;
is_bl = false;
}
// Conversely, if the original instruction was
// BLX but the target is Thumb mode, use the BL stub.
else if (force_target_thumb
&& stub_type == arm_stub_a8_veneer_blx)
{
stub_type = arm_stub_a8_veneer_bl;
is_blx = false;
is_bl = true;
}
if (is_blx)
pc_for_insn &= ~3;
// If we found a relocation, use the proper destination,
// not the offset in the (unrelocated) instruction.
// Note this is always done if we switched the stub type above.
if (cortex_a8_reloc != NULL)
offset = (off_t) (cortex_a8_reloc->destination() - pc_for_insn);
Arm_address target = (pc_for_insn + offset) | (is_blx ? 0 : 1);
// Add a new stub if destination address in in the same page.
if (((address + i) & ~0xfffU) == (target & ~0xfffU))
{
Cortex_a8_stub* stub =
this->stub_factory_.make_cortex_a8_stub(stub_type,
arm_relobj, shndx,
address + i,
target, insn);
Stub_table<big_endian>* stub_table =
arm_relobj->stub_table(shndx);
gold_assert(stub_table != NULL);
stub_table->add_cortex_a8_stub(address + i, stub);
}
}
}
i += insn_32bit ? 4 : 2;
last_was_32bit = insn_32bit;
last_was_branch = is_32bit_branch;
}
}
template<bool big_endian>
class Target_selector_arm : public Target_selector
{