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old-cross-binutils/gold/script-sections.cc
Ian Lance Taylor 3ee173de46 * script-sections.cc (Script_sections::create_segments): Don't put 
program headers in a PT_LOAD segment if -n or -N.
2009-06-23 06:07:50 +00:00

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// script-sections.cc -- linker script SECTIONS for gold
// Copyright 2008, 2009 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include <cstring>
#include <algorithm>
#include <list>
#include <map>
#include <string>
#include <vector>
#include <fnmatch.h>
#include "parameters.h"
#include "object.h"
#include "layout.h"
#include "output.h"
#include "script-c.h"
#include "script.h"
#include "script-sections.h"
// Support for the SECTIONS clause in linker scripts.
namespace gold
{
// Manage orphan sections. This is intended to be largely compatible
// with the GNU linker. The Linux kernel implicitly relies on
// something similar to the GNU linker's orphan placement. We
// originally used a simpler scheme here, but it caused the kernel
// build to fail, and was also rather inefficient.
class Orphan_section_placement
{
private:
typedef Script_sections::Elements_iterator Elements_iterator;
public:
Orphan_section_placement();
// Handle an output section during initialization of this mapping.
void
output_section_init(const std::string& name, Output_section*,
Elements_iterator location);
// Initialize the last location.
void
last_init(Elements_iterator location);
// Set *PWHERE to the address of an iterator pointing to the
// location to use for an orphan section. Return true if the
// iterator has a value, false otherwise.
bool
find_place(Output_section*, Elements_iterator** pwhere);
// Return the iterator being used for sections at the very end of
// the linker script.
Elements_iterator
last_place() const;
private:
// The places that we specifically recognize. This list is copied
// from the GNU linker.
enum Place_index
{
PLACE_TEXT,
PLACE_RODATA,
PLACE_DATA,
PLACE_BSS,
PLACE_REL,
PLACE_INTERP,
PLACE_NONALLOC,
PLACE_LAST,
PLACE_MAX
};
// The information we keep for a specific place.
struct Place
{
// The name of sections for this place.
const char* name;
// Whether we have a location for this place.
bool have_location;
// The iterator for this place.
Elements_iterator location;
};
// Initialize one place element.
void
initialize_place(Place_index, const char*);
// The places.
Place places_[PLACE_MAX];
// True if this is the first call to output_section_init.
bool first_init_;
};
// Initialize Orphan_section_placement.
Orphan_section_placement::Orphan_section_placement()
: first_init_(true)
{
this->initialize_place(PLACE_TEXT, ".text");
this->initialize_place(PLACE_RODATA, ".rodata");
this->initialize_place(PLACE_DATA, ".data");
this->initialize_place(PLACE_BSS, ".bss");
this->initialize_place(PLACE_REL, NULL);
this->initialize_place(PLACE_INTERP, ".interp");
this->initialize_place(PLACE_NONALLOC, NULL);
this->initialize_place(PLACE_LAST, NULL);
}
// Initialize one place element.
void
Orphan_section_placement::initialize_place(Place_index index, const char* name)
{
this->places_[index].name = name;
this->places_[index].have_location = false;
}
// While initializing the Orphan_section_placement information, this
// is called once for each output section named in the linker script.
// If we found an output section during the link, it will be passed in
// OS.
void
Orphan_section_placement::output_section_init(const std::string& name,
Output_section* os,
Elements_iterator location)
{
bool first_init = this->first_init_;
this->first_init_ = false;
for (int i = 0; i < PLACE_MAX; ++i)
{
if (this->places_[i].name != NULL && this->places_[i].name == name)
{
if (this->places_[i].have_location)
{
// We have already seen a section with this name.
return;
}
this->places_[i].location = location;
this->places_[i].have_location = true;
// If we just found the .bss section, restart the search for
// an unallocated section. This follows the GNU linker's
// behaviour.
if (i == PLACE_BSS)
this->places_[PLACE_NONALLOC].have_location = false;
return;
}
}
// Relocation sections.
if (!this->places_[PLACE_REL].have_location
&& os != NULL
&& (os->type() == elfcpp::SHT_REL || os->type() == elfcpp::SHT_RELA)
&& (os->flags() & elfcpp::SHF_ALLOC) != 0)
{
this->places_[PLACE_REL].location = location;
this->places_[PLACE_REL].have_location = true;
}
// We find the location for unallocated sections by finding the
// first debugging or comment section after the BSS section (if
// there is one).
if (!this->places_[PLACE_NONALLOC].have_location
&& (name == ".comment" || Layout::is_debug_info_section(name.c_str())))
{
// We add orphan sections after the location in PLACES_. We
// want to store unallocated sections before LOCATION. If this
// is the very first section, we can't use it.
if (!first_init)
{
--location;
this->places_[PLACE_NONALLOC].location = location;
this->places_[PLACE_NONALLOC].have_location = true;
}
}
}
// Initialize the last location.
void
Orphan_section_placement::last_init(Elements_iterator location)
{
this->places_[PLACE_LAST].location = location;
this->places_[PLACE_LAST].have_location = true;
}
// Set *PWHERE to the address of an iterator pointing to the location
// to use for an orphan section. Return true if the iterator has a
// value, false otherwise.
bool
Orphan_section_placement::find_place(Output_section* os,
Elements_iterator** pwhere)
{
// Figure out where OS should go. This is based on the GNU linker
// code. FIXME: The GNU linker handles small data sections
// specially, but we don't.
elfcpp::Elf_Word type = os->type();
elfcpp::Elf_Xword flags = os->flags();
Place_index index;
if ((flags & elfcpp::SHF_ALLOC) == 0
&& !Layout::is_debug_info_section(os->name()))
index = PLACE_NONALLOC;
else if ((flags & elfcpp::SHF_ALLOC) == 0)
index = PLACE_LAST;
else if (type == elfcpp::SHT_NOTE)
index = PLACE_INTERP;
else if (type == elfcpp::SHT_NOBITS)
index = PLACE_BSS;
else if ((flags & elfcpp::SHF_WRITE) != 0)
index = PLACE_DATA;
else if (type == elfcpp::SHT_REL || type == elfcpp::SHT_RELA)
index = PLACE_REL;
else if ((flags & elfcpp::SHF_EXECINSTR) == 0)
index = PLACE_RODATA;
else
index = PLACE_TEXT;
// If we don't have a location yet, try to find one based on a
// plausible ordering of sections.
if (!this->places_[index].have_location)
{
Place_index follow;
switch (index)
{
default:
follow = PLACE_MAX;
break;
case PLACE_RODATA:
follow = PLACE_TEXT;
break;
case PLACE_BSS:
follow = PLACE_DATA;
break;
case PLACE_REL:
follow = PLACE_TEXT;
break;
case PLACE_INTERP:
follow = PLACE_TEXT;
break;
}
if (follow != PLACE_MAX && this->places_[follow].have_location)
{
// Set the location of INDEX to the location of FOLLOW. The
// location of INDEX will then be incremented by the caller,
// so anything in INDEX will continue to be after anything
// in FOLLOW.
this->places_[index].location = this->places_[follow].location;
this->places_[index].have_location = true;
}
}
*pwhere = &this->places_[index].location;
bool ret = this->places_[index].have_location;
// The caller will set the location.
this->places_[index].have_location = true;
return ret;
}
// Return the iterator being used for sections at the very end of the
// linker script.
Orphan_section_placement::Elements_iterator
Orphan_section_placement::last_place() const
{
gold_assert(this->places_[PLACE_LAST].have_location);
return this->places_[PLACE_LAST].location;
}
// An element in a SECTIONS clause.
class Sections_element
{
public:
Sections_element()
{ }
virtual ~Sections_element()
{ }
// Return whether an output section is relro.
virtual bool
is_relro() const
{ return false; }
// Record that an output section is relro.
virtual void
set_is_relro()
{ }
// Create any required output sections. The only real
// implementation is in Output_section_definition.
virtual void
create_sections(Layout*)
{ }
// Add any symbol being defined to the symbol table.
virtual void
add_symbols_to_table(Symbol_table*)
{ }
// Finalize symbols and check assertions.
virtual void
finalize_symbols(Symbol_table*, const Layout*, uint64_t*)
{ }
// Return the output section name to use for an input file name and
// section name. This only real implementation is in
// Output_section_definition.
virtual const char*
output_section_name(const char*, const char*, Output_section***)
{ return NULL; }
// Initialize OSP with an output section.
virtual void
orphan_section_init(Orphan_section_placement*,
Script_sections::Elements_iterator)
{ }
// Set section addresses. This includes applying assignments if the
// the expression is an absolute value.
virtual void
set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*)
{ }
// Check a constraint (ONLY_IF_RO, etc.) on an output section. If
// this section is constrained, and the input sections do not match,
// return the constraint, and set *POSD.
virtual Section_constraint
check_constraint(Output_section_definition**)
{ return CONSTRAINT_NONE; }
// See if this is the alternate output section for a constrained
// output section. If it is, transfer the Output_section and return
// true. Otherwise return false.
virtual bool
alternate_constraint(Output_section_definition*, Section_constraint)
{ return false; }
// Get the list of segments to use for an allocated section when
// using a PHDRS clause. If this is an allocated section, return
// the Output_section, and set *PHDRS_LIST (the first parameter) to
// the list of PHDRS to which it should be attached. If the PHDRS
// were not specified, don't change *PHDRS_LIST. When not returning
// NULL, set *ORPHAN (the second parameter) according to whether
// this is an orphan section--one that is not mentioned in the
// linker script.
virtual Output_section*
allocate_to_segment(String_list**, bool*)
{ return NULL; }
// Look for an output section by name and return the address, the
// load address, the alignment, and the size. This is used when an
// expression refers to an output section which was not actually
// created. This returns true if the section was found, false
// otherwise. The only real definition is for
// Output_section_definition.
virtual bool
get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*,
uint64_t*) const
{ return false; }
// Return the associated Output_section if there is one.
virtual Output_section*
get_output_section() const
{ return NULL; }
// Print the element for debugging purposes.
virtual void
print(FILE* f) const = 0;
};
// An assignment in a SECTIONS clause outside of an output section.
class Sections_element_assignment : public Sections_element
{
public:
Sections_element_assignment(const char* name, size_t namelen,
Expression* val, bool provide, bool hidden)
: assignment_(name, namelen, val, provide, hidden)
{ }
// Add the symbol to the symbol table.
void
add_symbols_to_table(Symbol_table* symtab)
{ this->assignment_.add_to_table(symtab); }
// Finalize the symbol.
void
finalize_symbols(Symbol_table* symtab, const Layout* layout,
uint64_t* dot_value)
{
this->assignment_.finalize_with_dot(symtab, layout, *dot_value, NULL);
}
// Set the section address. There is no section here, but if the
// value is absolute, we set the symbol. This permits us to use
// absolute symbols when setting dot.
void
set_section_addresses(Symbol_table* symtab, Layout* layout,
uint64_t* dot_value, uint64_t*)
{
this->assignment_.set_if_absolute(symtab, layout, true, *dot_value);
}
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " ");
this->assignment_.print(f);
}
private:
Symbol_assignment assignment_;
};
// An assignment to the dot symbol in a SECTIONS clause outside of an
// output section.
class Sections_element_dot_assignment : public Sections_element
{
public:
Sections_element_dot_assignment(Expression* val)
: val_(val)
{ }
// Finalize the symbol.
void
finalize_symbols(Symbol_table* symtab, const Layout* layout,
uint64_t* dot_value)
{
// We ignore the section of the result because outside of an
// output section definition the dot symbol is always considered
// to be absolute.
Output_section* dummy;
*dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
NULL, &dummy);
}
// Update the dot symbol while setting section addresses.
void
set_section_addresses(Symbol_table* symtab, Layout* layout,
uint64_t* dot_value, uint64_t* load_address)
{
Output_section* dummy;
*dot_value = this->val_->eval_with_dot(symtab, layout, false, *dot_value,
NULL, &dummy);
*load_address = *dot_value;
}
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " . = ");
this->val_->print(f);
fprintf(f, "\n");
}
private:
Expression* val_;
};
// An assertion in a SECTIONS clause outside of an output section.
class Sections_element_assertion : public Sections_element
{
public:
Sections_element_assertion(Expression* check, const char* message,
size_t messagelen)
: assertion_(check, message, messagelen)
{ }
// Check the assertion.
void
finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t*)
{ this->assertion_.check(symtab, layout); }
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " ");
this->assertion_.print(f);
}
private:
Script_assertion assertion_;
};
// An element in an output section in a SECTIONS clause.
class Output_section_element
{
public:
// A list of input sections.
typedef std::list<std::pair<Relobj*, unsigned int> > Input_section_list;
Output_section_element()
{ }
virtual ~Output_section_element()
{ }
// Return whether this element requires an output section to exist.
virtual bool
needs_output_section() const
{ return false; }
// Add any symbol being defined to the symbol table.
virtual void
add_symbols_to_table(Symbol_table*)
{ }
// Finalize symbols and check assertions.
virtual void
finalize_symbols(Symbol_table*, const Layout*, uint64_t*, Output_section**)
{ }
// Return whether this element matches FILE_NAME and SECTION_NAME.
// The only real implementation is in Output_section_element_input.
virtual bool
match_name(const char*, const char*) const
{ return false; }
// Set section addresses. This includes applying assignments if the
// the expression is an absolute value.
virtual void
set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t,
uint64_t*, Output_section**, std::string*,
Input_section_list*)
{ }
// Print the element for debugging purposes.
virtual void
print(FILE* f) const = 0;
protected:
// Return a fill string that is LENGTH bytes long, filling it with
// FILL.
std::string
get_fill_string(const std::string* fill, section_size_type length) const;
};
std::string
Output_section_element::get_fill_string(const std::string* fill,
section_size_type length) const
{
std::string this_fill;
this_fill.reserve(length);
while (this_fill.length() + fill->length() <= length)
this_fill += *fill;
if (this_fill.length() < length)
this_fill.append(*fill, 0, length - this_fill.length());
return this_fill;
}
// A symbol assignment in an output section.
class Output_section_element_assignment : public Output_section_element
{
public:
Output_section_element_assignment(const char* name, size_t namelen,
Expression* val, bool provide,
bool hidden)
: assignment_(name, namelen, val, provide, hidden)
{ }
// Add the symbol to the symbol table.
void
add_symbols_to_table(Symbol_table* symtab)
{ this->assignment_.add_to_table(symtab); }
// Finalize the symbol.
void
finalize_symbols(Symbol_table* symtab, const Layout* layout,
uint64_t* dot_value, Output_section** dot_section)
{
this->assignment_.finalize_with_dot(symtab, layout, *dot_value,
*dot_section);
}
// Set the section address. There is no section here, but if the
// value is absolute, we set the symbol. This permits us to use
// absolute symbols when setting dot.
void
set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
uint64_t, uint64_t* dot_value, Output_section**,
std::string*, Input_section_list*)
{
this->assignment_.set_if_absolute(symtab, layout, true, *dot_value);
}
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " ");
this->assignment_.print(f);
}
private:
Symbol_assignment assignment_;
};
// An assignment to the dot symbol in an output section.
class Output_section_element_dot_assignment : public Output_section_element
{
public:
Output_section_element_dot_assignment(Expression* val)
: val_(val)
{ }
// Finalize the symbol.
void
finalize_symbols(Symbol_table* symtab, const Layout* layout,
uint64_t* dot_value, Output_section** dot_section)
{
*dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
*dot_section, dot_section);
}
// Update the dot symbol while setting section addresses.
void
set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
uint64_t, uint64_t* dot_value, Output_section**,
std::string*, Input_section_list*);
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " . = ");
this->val_->print(f);
fprintf(f, "\n");
}
private:
Expression* val_;
};
// Update the dot symbol while setting section addresses.
void
Output_section_element_dot_assignment::set_section_addresses(
Symbol_table* symtab,
Layout* layout,
Output_section* output_section,
uint64_t,
uint64_t* dot_value,
Output_section** dot_section,
std::string* fill,
Input_section_list*)
{
uint64_t next_dot = this->val_->eval_with_dot(symtab, layout, false,
*dot_value, *dot_section,
dot_section);
if (next_dot < *dot_value)
gold_error(_("dot may not move backward"));
if (next_dot > *dot_value && output_section != NULL)
{
section_size_type length = convert_to_section_size_type(next_dot
- *dot_value);
Output_section_data* posd;
if (fill->empty())
posd = new Output_data_zero_fill(length, 0);
else
{
std::string this_fill = this->get_fill_string(fill, length);
posd = new Output_data_const(this_fill, 0);
}
output_section->add_output_section_data(posd);
}
*dot_value = next_dot;
}
// An assertion in an output section.
class Output_section_element_assertion : public Output_section_element
{
public:
Output_section_element_assertion(Expression* check, const char* message,
size_t messagelen)
: assertion_(check, message, messagelen)
{ }
void
print(FILE* f) const
{
fprintf(f, " ");
this->assertion_.print(f);
}
private:
Script_assertion assertion_;
};
// We use a special instance of Output_section_data to handle BYTE,
// SHORT, etc. This permits forward references to symbols in the
// expressions.
class Output_data_expression : public Output_section_data
{
public:
Output_data_expression(int size, bool is_signed, Expression* val,
const Symbol_table* symtab, const Layout* layout,
uint64_t dot_value, Output_section* dot_section)
: Output_section_data(size, 0),
is_signed_(is_signed), val_(val), symtab_(symtab),
layout_(layout), dot_value_(dot_value), dot_section_(dot_section)
{ }
protected:
// Write the data to the output file.
void
do_write(Output_file*);
// Write the data to a buffer.
void
do_write_to_buffer(unsigned char*);
// Write to a map file.
void
do_print_to_mapfile(Mapfile* mapfile) const
{ mapfile->print_output_data(this, _("** expression")); }
private:
template<bool big_endian>
void
endian_write_to_buffer(uint64_t, unsigned char*);
bool is_signed_;
Expression* val_;
const Symbol_table* symtab_;
const Layout* layout_;
uint64_t dot_value_;
Output_section* dot_section_;
};
// Write the data element to the output file.
void
Output_data_expression::do_write(Output_file* of)
{
unsigned char* view = of->get_output_view(this->offset(), this->data_size());
this->write_to_buffer(view);
of->write_output_view(this->offset(), this->data_size(), view);
}
// Write the data element to a buffer.
void
Output_data_expression::do_write_to_buffer(unsigned char* buf)
{
Output_section* dummy;
uint64_t val = this->val_->eval_with_dot(this->symtab_, this->layout_,
true, this->dot_value_,
this->dot_section_, &dummy);
if (parameters->target().is_big_endian())
this->endian_write_to_buffer<true>(val, buf);
else
this->endian_write_to_buffer<false>(val, buf);
}
template<bool big_endian>
void
Output_data_expression::endian_write_to_buffer(uint64_t val,
unsigned char* buf)
{
switch (this->data_size())
{
case 1:
elfcpp::Swap_unaligned<8, big_endian>::writeval(buf, val);
break;
case 2:
elfcpp::Swap_unaligned<16, big_endian>::writeval(buf, val);
break;
case 4:
elfcpp::Swap_unaligned<32, big_endian>::writeval(buf, val);
break;
case 8:
if (parameters->target().get_size() == 32)
{
val &= 0xffffffff;
if (this->is_signed_ && (val & 0x80000000) != 0)
val |= 0xffffffff00000000LL;
}
elfcpp::Swap_unaligned<64, big_endian>::writeval(buf, val);
break;
default:
gold_unreachable();
}
}
// A data item in an output section.
class Output_section_element_data : public Output_section_element
{
public:
Output_section_element_data(int size, bool is_signed, Expression* val)
: size_(size), is_signed_(is_signed), val_(val)
{ }
// If there is a data item, then we must create an output section.
bool
needs_output_section() const
{ return true; }
// Finalize symbols--we just need to update dot.
void
finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value,
Output_section**)
{ *dot_value += this->size_; }
// Store the value in the section.
void
set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t,
uint64_t* dot_value, Output_section**, std::string*,
Input_section_list*);
// Print for debugging.
void
print(FILE*) const;
private:
// The size in bytes.
int size_;
// Whether the value is signed.
bool is_signed_;
// The value.
Expression* val_;
};
// Store the value in the section.
void
Output_section_element_data::set_section_addresses(
Symbol_table* symtab,
Layout* layout,
Output_section* os,
uint64_t,
uint64_t* dot_value,
Output_section** dot_section,
std::string*,
Input_section_list*)
{
gold_assert(os != NULL);
os->add_output_section_data(new Output_data_expression(this->size_,
this->is_signed_,
this->val_,
symtab,
layout,
*dot_value,
*dot_section));
*dot_value += this->size_;
}
// Print for debugging.
void
Output_section_element_data::print(FILE* f) const
{
const char* s;
switch (this->size_)
{
case 1:
s = "BYTE";
break;
case 2:
s = "SHORT";
break;
case 4:
s = "LONG";
break;
case 8:
if (this->is_signed_)
s = "SQUAD";
else
s = "QUAD";
break;
default:
gold_unreachable();
}
fprintf(f, " %s(", s);
this->val_->print(f);
fprintf(f, ")\n");
}
// A fill value setting in an output section.
class Output_section_element_fill : public Output_section_element
{
public:
Output_section_element_fill(Expression* val)
: val_(val)
{ }
// Update the fill value while setting section addresses.
void
set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
uint64_t, uint64_t* dot_value,
Output_section** dot_section,
std::string* fill, Input_section_list*)
{
Output_section* fill_section;
uint64_t fill_val = this->val_->eval_with_dot(symtab, layout, false,
*dot_value, *dot_section,
&fill_section);
if (fill_section != NULL)
gold_warning(_("fill value is not absolute"));
// FIXME: The GNU linker supports fill values of arbitrary length.
unsigned char fill_buff[4];
elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val);
fill->assign(reinterpret_cast<char*>(fill_buff), 4);
}
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " FILL(");
this->val_->print(f);
fprintf(f, ")\n");
}
private:
// The new fill value.
Expression* val_;
};
// Return whether STRING contains a wildcard character. This is used
// to speed up matching.
static inline bool
is_wildcard_string(const std::string& s)
{
return strpbrk(s.c_str(), "?*[") != NULL;
}
// An input section specification in an output section
class Output_section_element_input : public Output_section_element
{
public:
Output_section_element_input(const Input_section_spec* spec, bool keep);
// Finalize symbols--just update the value of the dot symbol.
void
finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value,
Output_section** dot_section)
{
*dot_value = this->final_dot_value_;
*dot_section = this->final_dot_section_;
}
// See whether we match FILE_NAME and SECTION_NAME as an input
// section.
bool
match_name(const char* file_name, const char* section_name) const;
// Set the section address.
void
set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
uint64_t subalign, uint64_t* dot_value,
Output_section**, std::string* fill,
Input_section_list*);
// Print for debugging.
void
print(FILE* f) const;
private:
// An input section pattern.
struct Input_section_pattern
{
std::string pattern;
bool pattern_is_wildcard;
Sort_wildcard sort;
Input_section_pattern(const char* patterna, size_t patternlena,
Sort_wildcard sorta)
: pattern(patterna, patternlena),
pattern_is_wildcard(is_wildcard_string(this->pattern)),
sort(sorta)
{ }
};
typedef std::vector<Input_section_pattern> Input_section_patterns;
// Filename_exclusions is a pair of filename pattern and a bool
// indicating whether the filename is a wildcard.
typedef std::vector<std::pair<std::string, bool> > Filename_exclusions;
// Return whether STRING matches PATTERN, where IS_WILDCARD_PATTERN
// indicates whether this is a wildcard pattern.
static inline bool
match(const char* string, const char* pattern, bool is_wildcard_pattern)
{
return (is_wildcard_pattern
? fnmatch(pattern, string, 0) == 0
: strcmp(string, pattern) == 0);
}
// See if we match a file name.
bool
match_file_name(const char* file_name) const;
// The file name pattern. If this is the empty string, we match all
// files.
std::string filename_pattern_;
// Whether the file name pattern is a wildcard.
bool filename_is_wildcard_;
// How the file names should be sorted. This may only be
// SORT_WILDCARD_NONE or SORT_WILDCARD_BY_NAME.
Sort_wildcard filename_sort_;
// The list of file names to exclude.
Filename_exclusions filename_exclusions_;
// The list of input section patterns.
Input_section_patterns input_section_patterns_;
// Whether to keep this section when garbage collecting.
bool keep_;
// The value of dot after including all matching sections.
uint64_t final_dot_value_;
// The section where dot is defined after including all matching
// sections.
Output_section* final_dot_section_;
};
// Construct Output_section_element_input. The parser records strings
// as pointers into a copy of the script file, which will go away when
// parsing is complete. We make sure they are in std::string objects.
Output_section_element_input::Output_section_element_input(
const Input_section_spec* spec,
bool keep)
: filename_pattern_(),
filename_is_wildcard_(false),
filename_sort_(spec->file.sort),
filename_exclusions_(),
input_section_patterns_(),
keep_(keep),
final_dot_value_(0),
final_dot_section_(NULL)
{
// The filename pattern "*" is common, and matches all files. Turn
// it into the empty string.
if (spec->file.name.length != 1 || spec->file.name.value[0] != '*')
this->filename_pattern_.assign(spec->file.name.value,
spec->file.name.length);
this->filename_is_wildcard_ = is_wildcard_string(this->filename_pattern_);
if (spec->input_sections.exclude != NULL)
{
for (String_list::const_iterator p =
spec->input_sections.exclude->begin();
p != spec->input_sections.exclude->end();
++p)
{
bool is_wildcard = is_wildcard_string(*p);
this->filename_exclusions_.push_back(std::make_pair(*p,
is_wildcard));
}
}
if (spec->input_sections.sections != NULL)
{
Input_section_patterns& isp(this->input_section_patterns_);
for (String_sort_list::const_iterator p =
spec->input_sections.sections->begin();
p != spec->input_sections.sections->end();
++p)
isp.push_back(Input_section_pattern(p->name.value, p->name.length,
p->sort));
}
}
// See whether we match FILE_NAME.
bool
Output_section_element_input::match_file_name(const char* file_name) const
{
if (!this->filename_pattern_.empty())
{
// If we were called with no filename, we refuse to match a
// pattern which requires a file name.
if (file_name == NULL)
return false;
if (!match(file_name, this->filename_pattern_.c_str(),
this->filename_is_wildcard_))
return false;
}
if (file_name != NULL)
{
// Now we have to see whether FILE_NAME matches one of the
// exclusion patterns, if any.
for (Filename_exclusions::const_iterator p =
this->filename_exclusions_.begin();
p != this->filename_exclusions_.end();
++p)
{
if (match(file_name, p->first.c_str(), p->second))
return false;
}
}
return true;
}
// See whether we match FILE_NAME and SECTION_NAME.
bool
Output_section_element_input::match_name(const char* file_name,
const char* section_name) const
{
if (!this->match_file_name(file_name))
return false;
// If there are no section name patterns, then we match.
if (this->input_section_patterns_.empty())
return true;
// See whether we match the section name patterns.
for (Input_section_patterns::const_iterator p =
this->input_section_patterns_.begin();
p != this->input_section_patterns_.end();
++p)
{
if (match(section_name, p->pattern.c_str(), p->pattern_is_wildcard))
return true;
}
// We didn't match any section names, so we didn't match.
return false;
}
// Information we use to sort the input sections.
struct Input_section_info
{
Relobj* relobj;
unsigned int shndx;
std::string section_name;
uint64_t size;
uint64_t addralign;
};
// A class to sort the input sections.
class Input_section_sorter
{
public:
Input_section_sorter(Sort_wildcard filename_sort, Sort_wildcard section_sort)
: filename_sort_(filename_sort), section_sort_(section_sort)
{ }
bool
operator()(const Input_section_info&, const Input_section_info&) const;
private:
Sort_wildcard filename_sort_;
Sort_wildcard section_sort_;
};
bool
Input_section_sorter::operator()(const Input_section_info& isi1,
const Input_section_info& isi2) const
{
if (this->section_sort_ == SORT_WILDCARD_BY_NAME
|| this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT
|| (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME
&& isi1.addralign == isi2.addralign))
{
if (isi1.section_name != isi2.section_name)
return isi1.section_name < isi2.section_name;
}
if (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT
|| this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT
|| this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME)
{
if (isi1.addralign != isi2.addralign)
return isi1.addralign < isi2.addralign;
}
if (this->filename_sort_ == SORT_WILDCARD_BY_NAME)
{
if (isi1.relobj->name() != isi2.relobj->name())
return isi1.relobj->name() < isi2.relobj->name();
}
// Otherwise we leave them in the same order.
return false;
}
// Set the section address. Look in INPUT_SECTIONS for sections which
// match this spec, sort them as specified, and add them to the output
// section.
void
Output_section_element_input::set_section_addresses(
Symbol_table*,
Layout*,
Output_section* output_section,
uint64_t subalign,
uint64_t* dot_value,
Output_section** dot_section,
std::string* fill,
Input_section_list* input_sections)
{
// We build a list of sections which match each
// Input_section_pattern.
typedef std::vector<std::vector<Input_section_info> > Matching_sections;
size_t input_pattern_count = this->input_section_patterns_.size();
if (input_pattern_count == 0)
input_pattern_count = 1;
Matching_sections matching_sections(input_pattern_count);
// Look through the list of sections for this output section. Add
// each one which matches to one of the elements of
// MATCHING_SECTIONS.
Input_section_list::iterator p = input_sections->begin();
while (p != input_sections->end())
{
// Calling section_name and section_addralign is not very
// efficient.
Input_section_info isi;
isi.relobj = p->first;
isi.shndx = p->second;
// Lock the object so that we can get information about the
// section. This is OK since we know we are single-threaded
// here.
{
const Task* task = reinterpret_cast<const Task*>(-1);
Task_lock_obj<Object> tl(task, p->first);
isi.section_name = p->first->section_name(p->second);
isi.size = p->first->section_size(p->second);
isi.addralign = p->first->section_addralign(p->second);
}
if (!this->match_file_name(isi.relobj->name().c_str()))
++p;
else if (this->input_section_patterns_.empty())
{
matching_sections[0].push_back(isi);
p = input_sections->erase(p);
}
else
{
size_t i;
for (i = 0; i < input_pattern_count; ++i)
{
const Input_section_pattern&
isp(this->input_section_patterns_[i]);
if (match(isi.section_name.c_str(), isp.pattern.c_str(),
isp.pattern_is_wildcard))
break;
}
if (i >= this->input_section_patterns_.size())
++p;
else
{
matching_sections[i].push_back(isi);
p = input_sections->erase(p);
}
}
}
// Look through MATCHING_SECTIONS. Sort each one as specified,
// using a stable sort so that we get the default order when
// sections are otherwise equal. Add each input section to the
// output section.
for (size_t i = 0; i < input_pattern_count; ++i)
{
if (matching_sections[i].empty())
continue;
gold_assert(output_section != NULL);
const Input_section_pattern& isp(this->input_section_patterns_[i]);
if (isp.sort != SORT_WILDCARD_NONE
|| this->filename_sort_ != SORT_WILDCARD_NONE)
std::stable_sort(matching_sections[i].begin(),
matching_sections[i].end(),
Input_section_sorter(this->filename_sort_,
isp.sort));
for (std::vector<Input_section_info>::const_iterator p =
matching_sections[i].begin();
p != matching_sections[i].end();
++p)
{
uint64_t this_subalign = p->addralign;
if (this_subalign < subalign)
this_subalign = subalign;
uint64_t address = align_address(*dot_value, this_subalign);
if (address > *dot_value && !fill->empty())
{
section_size_type length =
convert_to_section_size_type(address - *dot_value);
std::string this_fill = this->get_fill_string(fill, length);
Output_section_data* posd = new Output_data_const(this_fill, 0);
output_section->add_output_section_data(posd);
}
output_section->add_input_section_for_script(p->relobj,
p->shndx,
p->size,
this_subalign);
*dot_value = address + p->size;
}
}
this->final_dot_value_ = *dot_value;
this->final_dot_section_ = *dot_section;
}
// Print for debugging.
void
Output_section_element_input::print(FILE* f) const
{
fprintf(f, " ");
if (this->keep_)
fprintf(f, "KEEP(");
if (!this->filename_pattern_.empty())
{
bool need_close_paren = false;
switch (this->filename_sort_)
{
case SORT_WILDCARD_NONE:
break;
case SORT_WILDCARD_BY_NAME:
fprintf(f, "SORT_BY_NAME(");
need_close_paren = true;
break;
default:
gold_unreachable();
}
fprintf(f, "%s", this->filename_pattern_.c_str());
if (need_close_paren)
fprintf(f, ")");
}
if (!this->input_section_patterns_.empty()
|| !this->filename_exclusions_.empty())
{
fprintf(f, "(");
bool need_space = false;
if (!this->filename_exclusions_.empty())
{
fprintf(f, "EXCLUDE_FILE(");
bool need_comma = false;
for (Filename_exclusions::const_iterator p =
this->filename_exclusions_.begin();
p != this->filename_exclusions_.end();
++p)
{
if (need_comma)
fprintf(f, ", ");
fprintf(f, "%s", p->first.c_str());
need_comma = true;
}
fprintf(f, ")");
need_space = true;
}
for (Input_section_patterns::const_iterator p =
this->input_section_patterns_.begin();
p != this->input_section_patterns_.end();
++p)
{
if (need_space)
fprintf(f, " ");
int close_parens = 0;
switch (p->sort)
{
case SORT_WILDCARD_NONE:
break;
case SORT_WILDCARD_BY_NAME:
fprintf(f, "SORT_BY_NAME(");
close_parens = 1;
break;
case SORT_WILDCARD_BY_ALIGNMENT:
fprintf(f, "SORT_BY_ALIGNMENT(");
close_parens = 1;
break;
case SORT_WILDCARD_BY_NAME_BY_ALIGNMENT:
fprintf(f, "SORT_BY_NAME(SORT_BY_ALIGNMENT(");
close_parens = 2;
break;
case SORT_WILDCARD_BY_ALIGNMENT_BY_NAME:
fprintf(f, "SORT_BY_ALIGNMENT(SORT_BY_NAME(");
close_parens = 2;
break;
default:
gold_unreachable();
}
fprintf(f, "%s", p->pattern.c_str());
for (int i = 0; i < close_parens; ++i)
fprintf(f, ")");
need_space = true;
}
fprintf(f, ")");
}
if (this->keep_)
fprintf(f, ")");
fprintf(f, "\n");
}
// An output section.
class Output_section_definition : public Sections_element
{
public:
typedef Output_section_element::Input_section_list Input_section_list;
Output_section_definition(const char* name, size_t namelen,
const Parser_output_section_header* header);
// Finish the output section with the information in the trailer.
void
finish(const Parser_output_section_trailer* trailer);
// Add a symbol to be defined.
void
add_symbol_assignment(const char* name, size_t length, Expression* value,
bool provide, bool hidden);
// Add an assignment to the special dot symbol.
void
add_dot_assignment(Expression* value);
// Add an assertion.
void
add_assertion(Expression* check, const char* message, size_t messagelen);
// Add a data item to the current output section.
void
add_data(int size, bool is_signed, Expression* val);
// Add a setting for the fill value.
void
add_fill(Expression* val);
// Add an input section specification.
void
add_input_section(const Input_section_spec* spec, bool keep);
// Return whether the output section is relro.
bool
is_relro() const
{ return this->is_relro_; }
// Record that the output section is relro.
void
set_is_relro()
{ this->is_relro_ = true; }
// Create any required output sections.
void
create_sections(Layout*);
// Add any symbols being defined to the symbol table.
void
add_symbols_to_table(Symbol_table* symtab);
// Finalize symbols and check assertions.
void
finalize_symbols(Symbol_table*, const Layout*, uint64_t*);
// Return the output section name to use for an input file name and
// section name.
const char*
output_section_name(const char* file_name, const char* section_name,
Output_section***);
// Initialize OSP with an output section.
void
orphan_section_init(Orphan_section_placement* osp,
Script_sections::Elements_iterator p)
{ osp->output_section_init(this->name_, this->output_section_, p); }
// Set the section address.
void
set_section_addresses(Symbol_table* symtab, Layout* layout,
uint64_t* dot_value, uint64_t* load_address);
// Check a constraint (ONLY_IF_RO, etc.) on an output section. If
// this section is constrained, and the input sections do not match,
// return the constraint, and set *POSD.
Section_constraint
check_constraint(Output_section_definition** posd);
// See if this is the alternate output section for a constrained
// output section. If it is, transfer the Output_section and return
// true. Otherwise return false.
bool
alternate_constraint(Output_section_definition*, Section_constraint);
// Get the list of segments to use for an allocated section when
// using a PHDRS clause.
Output_section*
allocate_to_segment(String_list** phdrs_list, bool* orphan);
// Look for an output section by name and return the address, the
// load address, the alignment, and the size. This is used when an
// expression refers to an output section which was not actually
// created. This returns true if the section was found, false
// otherwise.
bool
get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*,
uint64_t*) const;
// Return the associated Output_section if there is one.
Output_section*
get_output_section() const
{ return this->output_section_; }
// Print the contents to the FILE. This is for debugging.
void
print(FILE*) const;
private:
typedef std::vector<Output_section_element*> Output_section_elements;
// The output section name.
std::string name_;
// The address. This may be NULL.
Expression* address_;
// The load address. This may be NULL.
Expression* load_address_;
// The alignment. This may be NULL.
Expression* align_;
// The input section alignment. This may be NULL.
Expression* subalign_;
// The constraint, if any.
Section_constraint constraint_;
// The fill value. This may be NULL.
Expression* fill_;
// The list of segments this section should go into. This may be
// NULL.
String_list* phdrs_;
// The list of elements defining the section.
Output_section_elements elements_;
// The Output_section created for this definition. This will be
// NULL if none was created.
Output_section* output_section_;
// The address after it has been evaluated.
uint64_t evaluated_address_;
// The load address after it has been evaluated.
uint64_t evaluated_load_address_;
// The alignment after it has been evaluated.
uint64_t evaluated_addralign_;
// The output section is relro.
bool is_relro_;
};
// Constructor.
Output_section_definition::Output_section_definition(
const char* name,
size_t namelen,
const Parser_output_section_header* header)
: name_(name, namelen),
address_(header->address),
load_address_(header->load_address),
align_(header->align),
subalign_(header->subalign),
constraint_(header->constraint),
fill_(NULL),
phdrs_(NULL),
elements_(),
output_section_(NULL),
evaluated_address_(0),
evaluated_load_address_(0),
evaluated_addralign_(0),
is_relro_(false)
{
}
// Finish an output section.
void
Output_section_definition::finish(const Parser_output_section_trailer* trailer)
{
this->fill_ = trailer->fill;
this->phdrs_ = trailer->phdrs;
}
// Add a symbol to be defined.
void
Output_section_definition::add_symbol_assignment(const char* name,
size_t length,
Expression* value,
bool provide,
bool hidden)
{
Output_section_element* p = new Output_section_element_assignment(name,
length,
value,
provide,
hidden);
this->elements_.push_back(p);
}
// Add an assignment to the special dot symbol.
void
Output_section_definition::add_dot_assignment(Expression* value)
{
Output_section_element* p = new Output_section_element_dot_assignment(value);
this->elements_.push_back(p);
}
// Add an assertion.
void
Output_section_definition::add_assertion(Expression* check,
const char* message,
size_t messagelen)
{
Output_section_element* p = new Output_section_element_assertion(check,
message,
messagelen);
this->elements_.push_back(p);
}
// Add a data item to the current output section.
void
Output_section_definition::add_data(int size, bool is_signed, Expression* val)
{
Output_section_element* p = new Output_section_element_data(size, is_signed,
val);
this->elements_.push_back(p);
}
// Add a setting for the fill value.
void
Output_section_definition::add_fill(Expression* val)
{
Output_section_element* p = new Output_section_element_fill(val);
this->elements_.push_back(p);
}
// Add an input section specification.
void
Output_section_definition::add_input_section(const Input_section_spec* spec,
bool keep)
{
Output_section_element* p = new Output_section_element_input(spec, keep);
this->elements_.push_back(p);
}
// Create any required output sections. We need an output section if
// there is a data statement here.
void
Output_section_definition::create_sections(Layout* layout)
{
if (this->output_section_ != NULL)
return;
for (Output_section_elements::const_iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
{
if ((*p)->needs_output_section())
{
const char* name = this->name_.c_str();
this->output_section_ = layout->make_output_section_for_script(name);
return;
}
}
}
// Add any symbols being defined to the symbol table.
void
Output_section_definition::add_symbols_to_table(Symbol_table* symtab)
{
for (Output_section_elements::iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
(*p)->add_symbols_to_table(symtab);
}
// Finalize symbols and check assertions.
void
Output_section_definition::finalize_symbols(Symbol_table* symtab,
const Layout* layout,
uint64_t* dot_value)
{
if (this->output_section_ != NULL)
*dot_value = this->output_section_->address();
else
{
uint64_t address = *dot_value;
if (this->address_ != NULL)
{
Output_section* dummy;
address = this->address_->eval_with_dot(symtab, layout, true,
*dot_value, NULL,
&dummy);
}
if (this->align_ != NULL)
{
Output_section* dummy;
uint64_t align = this->align_->eval_with_dot(symtab, layout, true,
*dot_value,
NULL,
&dummy);
address = align_address(address, align);
}
*dot_value = address;
}
Output_section* dot_section = this->output_section_;
for (Output_section_elements::iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
(*p)->finalize_symbols(symtab, layout, dot_value, &dot_section);
}
// Return the output section name to use for an input section name.
const char*
Output_section_definition::output_section_name(const char* file_name,
const char* section_name,
Output_section*** slot)
{
// Ask each element whether it matches NAME.
for (Output_section_elements::const_iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
{
if ((*p)->match_name(file_name, section_name))
{
// We found a match for NAME, which means that it should go
// into this output section.
*slot = &this->output_section_;
return this->name_.c_str();
}
}
// We don't know about this section name.
return NULL;
}
// Set the section address. Note that the OUTPUT_SECTION_ field will
// be NULL if no input sections were mapped to this output section.
// We still have to adjust dot and process symbol assignments.
void
Output_section_definition::set_section_addresses(Symbol_table* symtab,
Layout* layout,
uint64_t* dot_value,
uint64_t* load_address)
{
uint64_t address;
if (this->address_ == NULL)
address = *dot_value;
else
{
Output_section* dummy;
address = this->address_->eval_with_dot(symtab, layout, true,
*dot_value, NULL, &dummy);
}
uint64_t align;
if (this->align_ == NULL)
{
if (this->output_section_ == NULL)
align = 0;
else
align = this->output_section_->addralign();
}
else
{
Output_section* align_section;
align = this->align_->eval_with_dot(symtab, layout, true, *dot_value,
NULL, &align_section);
if (align_section != NULL)
gold_warning(_("alignment of section %s is not absolute"),
this->name_.c_str());
if (this->output_section_ != NULL)
this->output_section_->set_addralign(align);
}
address = align_address(address, align);
uint64_t start_address = address;
*dot_value = address;
// The address of non-SHF_ALLOC sections is forced to zero,
// regardless of what the linker script wants.
if (this->output_section_ != NULL
&& (this->output_section_->flags() & elfcpp::SHF_ALLOC) != 0)
this->output_section_->set_address(address);
this->evaluated_address_ = address;
this->evaluated_addralign_ = align;
if (this->load_address_ == NULL)
this->evaluated_load_address_ = address;
else
{
Output_section* dummy;
uint64_t load_address =
this->load_address_->eval_with_dot(symtab, layout, true, *dot_value,
this->output_section_, &dummy);
if (this->output_section_ != NULL)
this->output_section_->set_load_address(load_address);
this->evaluated_load_address_ = load_address;
}
uint64_t subalign;
if (this->subalign_ == NULL)
subalign = 0;
else
{
Output_section* subalign_section;
subalign = this->subalign_->eval_with_dot(symtab, layout, true,
*dot_value, NULL,
&subalign_section);
if (subalign_section != NULL)
gold_warning(_("subalign of section %s is not absolute"),
this->name_.c_str());
}
std::string fill;
if (this->fill_ != NULL)
{
// FIXME: The GNU linker supports fill values of arbitrary
// length.
Output_section* fill_section;
uint64_t fill_val = this->fill_->eval_with_dot(symtab, layout, true,
*dot_value,
NULL,
&fill_section);
if (fill_section != NULL)
gold_warning(_("fill of section %s is not absolute"),
this->name_.c_str());
unsigned char fill_buff[4];
elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val);
fill.assign(reinterpret_cast<char*>(fill_buff), 4);
}
Input_section_list input_sections;
if (this->output_section_ != NULL)
{
// Get the list of input sections attached to this output
// section. This will leave the output section with only
// Output_section_data entries.
address += this->output_section_->get_input_sections(address,
fill,
&input_sections);
*dot_value = address;
}
Output_section* dot_section = this->output_section_;
for (Output_section_elements::iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
(*p)->set_section_addresses(symtab, layout, this->output_section_,
subalign, dot_value, &dot_section, &fill,
&input_sections);
gold_assert(input_sections.empty());
if (this->load_address_ == NULL || this->output_section_ == NULL)
*load_address = *dot_value;
else
*load_address = (this->output_section_->load_address()
+ (*dot_value - start_address));
if (this->output_section_ != NULL)
{
if (this->is_relro_)
this->output_section_->set_is_relro();
else
this->output_section_->clear_is_relro();
}
}
// Check a constraint (ONLY_IF_RO, etc.) on an output section. If
// this section is constrained, and the input sections do not match,
// return the constraint, and set *POSD.
Section_constraint
Output_section_definition::check_constraint(Output_section_definition** posd)
{
switch (this->constraint_)
{
case CONSTRAINT_NONE:
return CONSTRAINT_NONE;
case CONSTRAINT_ONLY_IF_RO:
if (this->output_section_ != NULL
&& (this->output_section_->flags() & elfcpp::SHF_WRITE) != 0)
{
*posd = this;
return CONSTRAINT_ONLY_IF_RO;
}
return CONSTRAINT_NONE;
case CONSTRAINT_ONLY_IF_RW:
if (this->output_section_ != NULL
&& (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0)
{
*posd = this;
return CONSTRAINT_ONLY_IF_RW;
}
return CONSTRAINT_NONE;
case CONSTRAINT_SPECIAL:
if (this->output_section_ != NULL)
gold_error(_("SPECIAL constraints are not implemented"));
return CONSTRAINT_NONE;
default:
gold_unreachable();
}
}
// See if this is the alternate output section for a constrained
// output section. If it is, transfer the Output_section and return
// true. Otherwise return false.
bool
Output_section_definition::alternate_constraint(
Output_section_definition* posd,
Section_constraint constraint)
{
if (this->name_ != posd->name_)
return false;
switch (constraint)
{
case CONSTRAINT_ONLY_IF_RO:
if (this->constraint_ != CONSTRAINT_ONLY_IF_RW)
return false;
break;
case CONSTRAINT_ONLY_IF_RW:
if (this->constraint_ != CONSTRAINT_ONLY_IF_RO)
return false;
break;
default:
gold_unreachable();
}
// We have found the alternate constraint. We just need to move
// over the Output_section. When constraints are used properly,
// THIS should not have an output_section pointer, as all the input
// sections should have matched the other definition.
if (this->output_section_ != NULL)
gold_error(_("mismatched definition for constrained sections"));
this->output_section_ = posd->output_section_;
posd->output_section_ = NULL;
if (this->is_relro_)
this->output_section_->set_is_relro();
else
this->output_section_->clear_is_relro();
return true;
}
// Get the list of segments to use for an allocated section when using
// a PHDRS clause.
Output_section*
Output_section_definition::allocate_to_segment(String_list** phdrs_list,
bool* orphan)
{
if (this->output_section_ == NULL)
return NULL;
if ((this->output_section_->flags() & elfcpp::SHF_ALLOC) == 0)
return NULL;
*orphan = false;
if (this->phdrs_ != NULL)
*phdrs_list = this->phdrs_;
return this->output_section_;
}
// Look for an output section by name and return the address, the load
// address, the alignment, and the size. This is used when an
// expression refers to an output section which was not actually
// created. This returns true if the section was found, false
// otherwise.
bool
Output_section_definition::get_output_section_info(const char* name,
uint64_t* address,
uint64_t* load_address,
uint64_t* addralign,
uint64_t* size) const
{
if (this->name_ != name)
return false;
if (this->output_section_ != NULL)
{
*address = this->output_section_->address();
if (this->output_section_->has_load_address())
*load_address = this->output_section_->load_address();
else
*load_address = *address;
*addralign = this->output_section_->addralign();
*size = this->output_section_->current_data_size();
}
else
{
*address = this->evaluated_address_;
*load_address = this->evaluated_load_address_;
*addralign = this->evaluated_addralign_;
*size = 0;
}
return true;
}
// Print for debugging.
void
Output_section_definition::print(FILE* f) const
{
fprintf(f, " %s ", this->name_.c_str());
if (this->address_ != NULL)
{
this->address_->print(f);
fprintf(f, " ");
}
fprintf(f, ": ");
if (this->load_address_ != NULL)
{
fprintf(f, "AT(");
this->load_address_->print(f);
fprintf(f, ") ");
}
if (this->align_ != NULL)
{
fprintf(f, "ALIGN(");
this->align_->print(f);
fprintf(f, ") ");
}
if (this->subalign_ != NULL)
{
fprintf(f, "SUBALIGN(");
this->subalign_->print(f);
fprintf(f, ") ");
}
fprintf(f, "{\n");
for (Output_section_elements::const_iterator p = this->elements_.begin();
p != this->elements_.end();
++p)
(*p)->print(f);
fprintf(f, " }");
if (this->fill_ != NULL)
{
fprintf(f, " = ");
this->fill_->print(f);
}
if (this->phdrs_ != NULL)
{
for (String_list::const_iterator p = this->phdrs_->begin();
p != this->phdrs_->end();
++p)
fprintf(f, " :%s", p->c_str());
}
fprintf(f, "\n");
}
// An output section created to hold orphaned input sections. These
// do not actually appear in linker scripts. However, for convenience
// when setting the output section addresses, we put a marker to these
// sections in the appropriate place in the list of SECTIONS elements.
class Orphan_output_section : public Sections_element
{
public:
Orphan_output_section(Output_section* os)
: os_(os)
{ }
// Return whether the orphan output section is relro. We can just
// check the output section because we always set the flag, if
// needed, just after we create the Orphan_output_section.
bool
is_relro() const
{ return this->os_->is_relro(); }
// Initialize OSP with an output section. This should have been
// done already.
void
orphan_section_init(Orphan_section_placement*,
Script_sections::Elements_iterator)
{ gold_unreachable(); }
// Set section addresses.
void
set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*);
// Get the list of segments to use for an allocated section when
// using a PHDRS clause.
Output_section*
allocate_to_segment(String_list**, bool*);
// Return the associated Output_section.
Output_section*
get_output_section() const
{ return this->os_; }
// Print for debugging.
void
print(FILE* f) const
{
fprintf(f, " marker for orphaned output section %s\n",
this->os_->name());
}
private:
Output_section* os_;
};
// Set section addresses.
void
Orphan_output_section::set_section_addresses(Symbol_table*, Layout*,
uint64_t* dot_value,
uint64_t* load_address)
{
typedef std::list<std::pair<Relobj*, unsigned int> > Input_section_list;
bool have_load_address = *load_address != *dot_value;
uint64_t address = *dot_value;
address = align_address(address, this->os_->addralign());
if ((this->os_->flags() & elfcpp::SHF_ALLOC) != 0)
{
this->os_->set_address(address);
if (have_load_address)
this->os_->set_load_address(align_address(*load_address,
this->os_->addralign()));
}
Input_section_list input_sections;
address += this->os_->get_input_sections(address, "", &input_sections);
for (Input_section_list::iterator p = input_sections.begin();
p != input_sections.end();
++p)
{
uint64_t addralign;
uint64_t size;
// We know what are single-threaded, so it is OK to lock the
// object.
{
const Task* task = reinterpret_cast<const Task*>(-1);
Task_lock_obj<Object> tl(task, p->first);
addralign = p->first->section_addralign(p->second);
size = p->first->section_size(p->second);
}
address = align_address(address, addralign);
this->os_->add_input_section_for_script(p->first, p->second, size,
addralign);
address += size;
}
if (!have_load_address)
*load_address = address;
else
*load_address += address - *dot_value;
*dot_value = address;
}
// Get the list of segments to use for an allocated section when using
// a PHDRS clause. If this is an allocated section, return the
// Output_section. We don't change the list of segments.
Output_section*
Orphan_output_section::allocate_to_segment(String_list**, bool* orphan)
{
if ((this->os_->flags() & elfcpp::SHF_ALLOC) == 0)
return NULL;
*orphan = true;
return this->os_;
}
// Class Phdrs_element. A program header from a PHDRS clause.
class Phdrs_element
{
public:
Phdrs_element(const char* name, size_t namelen, unsigned int type,
bool includes_filehdr, bool includes_phdrs,
bool is_flags_valid, unsigned int flags,
Expression* load_address)
: name_(name, namelen), type_(type), includes_filehdr_(includes_filehdr),
includes_phdrs_(includes_phdrs), is_flags_valid_(is_flags_valid),
flags_(flags), load_address_(load_address), load_address_value_(0),
segment_(NULL)
{ }
// Return the name of this segment.
const std::string&
name() const
{ return this->name_; }
// Return the type of the segment.
unsigned int
type() const
{ return this->type_; }
// Whether to include the file header.
bool
includes_filehdr() const
{ return this->includes_filehdr_; }
// Whether to include the program headers.
bool
includes_phdrs() const
{ return this->includes_phdrs_; }
// Return whether there is a load address.
bool
has_load_address() const
{ return this->load_address_ != NULL; }
// Evaluate the load address expression if there is one.
void
eval_load_address(Symbol_table* symtab, Layout* layout)
{
if (this->load_address_ != NULL)
this->load_address_value_ = this->load_address_->eval(symtab, layout,
true);
}
// Return the load address.
uint64_t
load_address() const
{
gold_assert(this->load_address_ != NULL);
return this->load_address_value_;
}
// Create the segment.
Output_segment*
create_segment(Layout* layout)
{
this->segment_ = layout->make_output_segment(this->type_, this->flags_);
return this->segment_;
}
// Return the segment.
Output_segment*
segment()
{ return this->segment_; }
// Set the segment flags if appropriate.
void
set_flags_if_valid()
{
if (this->is_flags_valid_)
this->segment_->set_flags(this->flags_);
}
// Print for debugging.
void
print(FILE*) const;
private:
// The name used in the script.
std::string name_;
// The type of the segment (PT_LOAD, etc.).
unsigned int type_;
// Whether this segment includes the file header.
bool includes_filehdr_;
// Whether this segment includes the section headers.
bool includes_phdrs_;
// Whether the flags were explicitly specified.
bool is_flags_valid_;
// The flags for this segment (PF_R, etc.) if specified.
unsigned int flags_;
// The expression for the load address for this segment. This may
// be NULL.
Expression* load_address_;
// The actual load address from evaluating the expression.
uint64_t load_address_value_;
// The segment itself.
Output_segment* segment_;
};
// Print for debugging.
void
Phdrs_element::print(FILE* f) const
{
fprintf(f, " %s 0x%x", this->name_.c_str(), this->type_);
if (this->includes_filehdr_)
fprintf(f, " FILEHDR");
if (this->includes_phdrs_)
fprintf(f, " PHDRS");
if (this->is_flags_valid_)
fprintf(f, " FLAGS(%u)", this->flags_);
if (this->load_address_ != NULL)
{
fprintf(f, " AT(");
this->load_address_->print(f);
fprintf(f, ")");
}
fprintf(f, ";\n");
}
// Class Script_sections.
Script_sections::Script_sections()
: saw_sections_clause_(false),
in_sections_clause_(false),
sections_elements_(NULL),
output_section_(NULL),
phdrs_elements_(NULL),
orphan_section_placement_(NULL),
data_segment_align_start_(),
saw_data_segment_align_(false),
saw_relro_end_(false)
{
}
// Start a SECTIONS clause.
void
Script_sections::start_sections()
{
gold_assert(!this->in_sections_clause_ && this->output_section_ == NULL);
this->saw_sections_clause_ = true;
this->in_sections_clause_ = true;
if (this->sections_elements_ == NULL)
this->sections_elements_ = new Sections_elements;
}
// Finish a SECTIONS clause.
void
Script_sections::finish_sections()
{
gold_assert(this->in_sections_clause_ && this->output_section_ == NULL);
this->in_sections_clause_ = false;
}
// Add a symbol to be defined.
void
Script_sections::add_symbol_assignment(const char* name, size_t length,
Expression* val, bool provide,
bool hidden)
{
if (this->output_section_ != NULL)
this->output_section_->add_symbol_assignment(name, length, val,
provide, hidden);
else
{
Sections_element* p = new Sections_element_assignment(name, length,
val, provide,
hidden);
this->sections_elements_->push_back(p);
}
}
// Add an assignment to the special dot symbol.
void
Script_sections::add_dot_assignment(Expression* val)
{
if (this->output_section_ != NULL)
this->output_section_->add_dot_assignment(val);
else
{
Sections_element* p = new Sections_element_dot_assignment(val);
this->sections_elements_->push_back(p);
}
}
// Add an assertion.
void
Script_sections::add_assertion(Expression* check, const char* message,
size_t messagelen)
{
if (this->output_section_ != NULL)
this->output_section_->add_assertion(check, message, messagelen);
else
{
Sections_element* p = new Sections_element_assertion(check, message,
messagelen);
this->sections_elements_->push_back(p);
}
}
// Start processing entries for an output section.
void
Script_sections::start_output_section(
const char* name,
size_t namelen,
const Parser_output_section_header *header)
{
Output_section_definition* posd = new Output_section_definition(name,
namelen,
header);
this->sections_elements_->push_back(posd);
gold_assert(this->output_section_ == NULL);
this->output_section_ = posd;
}
// Stop processing entries for an output section.
void
Script_sections::finish_output_section(
const Parser_output_section_trailer* trailer)
{
gold_assert(this->output_section_ != NULL);
this->output_section_->finish(trailer);
this->output_section_ = NULL;
}
// Add a data item to the current output section.
void
Script_sections::add_data(int size, bool is_signed, Expression* val)
{
gold_assert(this->output_section_ != NULL);
this->output_section_->add_data(size, is_signed, val);
}
// Add a fill value setting to the current output section.
void
Script_sections::add_fill(Expression* val)
{
gold_assert(this->output_section_ != NULL);
this->output_section_->add_fill(val);
}
// Add an input section specification to the current output section.
void
Script_sections::add_input_section(const Input_section_spec* spec, bool keep)
{
gold_assert(this->output_section_ != NULL);
this->output_section_->add_input_section(spec, keep);
}
// This is called when we see DATA_SEGMENT_ALIGN. It means that any
// subsequent output sections may be relro.
void
Script_sections::data_segment_align()
{
if (this->saw_data_segment_align_)
gold_error(_("DATA_SEGMENT_ALIGN may only appear once in a linker script"));
gold_assert(!this->sections_elements_->empty());
Sections_elements::iterator p = this->sections_elements_->end();
--p;
this->data_segment_align_start_ = p;
this->saw_data_segment_align_ = true;
}
// This is called when we see DATA_SEGMENT_RELRO_END. It means that
// any output sections seen since DATA_SEGMENT_ALIGN are relro.
void
Script_sections::data_segment_relro_end()
{
if (this->saw_relro_end_)
gold_error(_("DATA_SEGMENT_RELRO_END may only appear once "
"in a linker script"));
this->saw_relro_end_ = true;
if (!this->saw_data_segment_align_)
gold_error(_("DATA_SEGMENT_RELRO_END must follow DATA_SEGMENT_ALIGN"));
else
{
Sections_elements::iterator p = this->data_segment_align_start_;
for (++p; p != this->sections_elements_->end(); ++p)
(*p)->set_is_relro();
}
}
// Create any required sections.
void
Script_sections::create_sections(Layout* layout)
{
if (!this->saw_sections_clause_)
return;
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->create_sections(layout);
}
// Add any symbols we are defining to the symbol table.
void
Script_sections::add_symbols_to_table(Symbol_table* symtab)
{
if (!this->saw_sections_clause_)
return;
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->add_symbols_to_table(symtab);
}
// Finalize symbols and check assertions.
void
Script_sections::finalize_symbols(Symbol_table* symtab, const Layout* layout)
{
if (!this->saw_sections_clause_)
return;
uint64_t dot_value = 0;
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->finalize_symbols(symtab, layout, &dot_value);
}
// Return the name of the output section to use for an input file name
// and section name.
const char*
Script_sections::output_section_name(const char* file_name,
const char* section_name,
Output_section*** output_section_slot)
{
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
const char* ret = (*p)->output_section_name(file_name, section_name,
output_section_slot);
if (ret != NULL)
{
// The special name /DISCARD/ means that the input section
// should be discarded.
if (strcmp(ret, "/DISCARD/") == 0)
{
*output_section_slot = NULL;
return NULL;
}
return ret;
}
}
// If we couldn't find a mapping for the name, the output section
// gets the name of the input section.
*output_section_slot = NULL;
return section_name;
}
// Place a marker for an orphan output section into the SECTIONS
// clause.
void
Script_sections::place_orphan(Output_section* os)
{
Orphan_section_placement* osp = this->orphan_section_placement_;
if (osp == NULL)
{
// Initialize the Orphan_section_placement structure.
osp = new Orphan_section_placement();
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->orphan_section_init(osp, p);
gold_assert(!this->sections_elements_->empty());
Sections_elements::iterator last = this->sections_elements_->end();
--last;
osp->last_init(last);
this->orphan_section_placement_ = osp;
}
Orphan_output_section* orphan = new Orphan_output_section(os);
// Look for where to put ORPHAN.
Sections_elements::iterator* where;
if (osp->find_place(os, &where))
{
if ((**where)->is_relro())
os->set_is_relro();
else
os->clear_is_relro();
// We want to insert ORPHAN after *WHERE, and then update *WHERE
// so that the next one goes after this one.
Sections_elements::iterator p = *where;
gold_assert(p != this->sections_elements_->end());
++p;
*where = this->sections_elements_->insert(p, orphan);
}
else
{
os->clear_is_relro();
// We don't have a place to put this orphan section. Put it,
// and all other sections like it, at the end, but before the
// sections which always come at the end.
Sections_elements::iterator last = osp->last_place();
*where = this->sections_elements_->insert(last, orphan);
}
}
// Set the addresses of all the output sections. Walk through all the
// elements, tracking the dot symbol. Apply assignments which set
// absolute symbol values, in case they are used when setting dot.
// Fill in data statement values. As we find output sections, set the
// address, set the address of all associated input sections, and
// update dot. Return the segment which should hold the file header
// and segment headers, if any.
Output_segment*
Script_sections::set_section_addresses(Symbol_table* symtab, Layout* layout)
{
gold_assert(this->saw_sections_clause_);
// Implement ONLY_IF_RO/ONLY_IF_RW constraints. These are a pain
// for our representation.
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
Output_section_definition* posd;
Section_constraint failed_constraint = (*p)->check_constraint(&posd);
if (failed_constraint != CONSTRAINT_NONE)
{
Sections_elements::iterator q;
for (q = this->sections_elements_->begin();
q != this->sections_elements_->end();
++q)
{
if (q != p)
{
if ((*q)->alternate_constraint(posd, failed_constraint))
break;
}
}
if (q == this->sections_elements_->end())
gold_error(_("no matching section constraint"));
}
}
// Force the alignment of the first TLS section to be the maximum
// alignment of all TLS sections.
Output_section* first_tls = NULL;
uint64_t tls_align = 0;
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
Output_section *os = (*p)->get_output_section();
if (os != NULL && (os->flags() & elfcpp::SHF_TLS) != 0)
{
if (first_tls == NULL)
first_tls = os;
if (os->addralign() > tls_align)
tls_align = os->addralign();
}
}
if (first_tls != NULL)
first_tls->set_addralign(tls_align);
// For a relocatable link, we implicitly set dot to zero.
uint64_t dot_value = 0;
uint64_t load_address = 0;
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->set_section_addresses(symtab, layout, &dot_value, &load_address);
if (this->phdrs_elements_ != NULL)
{
for (Phdrs_elements::iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
(*p)->eval_load_address(symtab, layout);
}
return this->create_segments(layout);
}
// Sort the sections in order to put them into segments.
class Sort_output_sections
{
public:
bool
operator()(const Output_section* os1, const Output_section* os2) const;
};
bool
Sort_output_sections::operator()(const Output_section* os1,
const Output_section* os2) const
{
// Sort first by the load address.
uint64_t lma1 = (os1->has_load_address()
? os1->load_address()
: os1->address());
uint64_t lma2 = (os2->has_load_address()
? os2->load_address()
: os2->address());
if (lma1 != lma2)
return lma1 < lma2;
// Then sort by the virtual address.
if (os1->address() != os2->address())
return os1->address() < os2->address();
// Sort TLS sections to the end.
bool tls1 = (os1->flags() & elfcpp::SHF_TLS) != 0;
bool tls2 = (os2->flags() & elfcpp::SHF_TLS) != 0;
if (tls1 != tls2)
return tls2;
// Sort PROGBITS before NOBITS.
if (os1->type() == elfcpp::SHT_PROGBITS && os2->type() == elfcpp::SHT_NOBITS)
return true;
if (os1->type() == elfcpp::SHT_NOBITS && os2->type() == elfcpp::SHT_PROGBITS)
return false;
// Otherwise we don't care.
return false;
}
// Return whether OS is a BSS section. This is a SHT_NOBITS section.
// We treat a section with the SHF_TLS flag set as taking up space
// even if it is SHT_NOBITS (this is true of .tbss), as we allocate
// space for them in the file.
bool
Script_sections::is_bss_section(const Output_section* os)
{
return (os->type() == elfcpp::SHT_NOBITS
&& (os->flags() & elfcpp::SHF_TLS) == 0);
}
// Return the size taken by the file header and the program headers.
size_t
Script_sections::total_header_size(Layout* layout) const
{
size_t segment_count = layout->segment_count();
size_t file_header_size;
size_t segment_headers_size;
if (parameters->target().get_size() == 32)
{
file_header_size = elfcpp::Elf_sizes<32>::ehdr_size;
segment_headers_size = segment_count * elfcpp::Elf_sizes<32>::phdr_size;
}
else if (parameters->target().get_size() == 64)
{
file_header_size = elfcpp::Elf_sizes<64>::ehdr_size;
segment_headers_size = segment_count * elfcpp::Elf_sizes<64>::phdr_size;
}
else
gold_unreachable();
return file_header_size + segment_headers_size;
}
// Return the amount we have to subtract from the LMA to accomodate
// headers of the given size. The complication is that the file
// header have to be at the start of a page, as otherwise it will not
// be at the start of the file.
uint64_t
Script_sections::header_size_adjustment(uint64_t lma,
size_t sizeof_headers) const
{
const uint64_t abi_pagesize = parameters->target().abi_pagesize();
uint64_t hdr_lma = lma - sizeof_headers;
hdr_lma &= ~(abi_pagesize - 1);
return lma - hdr_lma;
}
// Create the PT_LOAD segments when using a SECTIONS clause. Returns
// the segment which should hold the file header and segment headers,
// if any.
Output_segment*
Script_sections::create_segments(Layout* layout)
{
gold_assert(this->saw_sections_clause_);
if (parameters->options().relocatable())
return NULL;
if (this->saw_phdrs_clause())
return create_segments_from_phdrs_clause(layout);
Layout::Section_list sections;
layout->get_allocated_sections(&sections);
// Sort the sections by address.
std::stable_sort(sections.begin(), sections.end(), Sort_output_sections());
this->create_note_and_tls_segments(layout, &sections);
// Walk through the sections adding them to PT_LOAD segments.
const uint64_t abi_pagesize = parameters->target().abi_pagesize();
Output_segment* first_seg = NULL;
Output_segment* current_seg = NULL;
bool is_current_seg_readonly = true;
Layout::Section_list::iterator plast = sections.end();
uint64_t last_vma = 0;
uint64_t last_lma = 0;
uint64_t last_size = 0;
for (Layout::Section_list::iterator p = sections.begin();
p != sections.end();
++p)
{
const uint64_t vma = (*p)->address();
const uint64_t lma = ((*p)->has_load_address()
? (*p)->load_address()
: vma);
const uint64_t size = (*p)->current_data_size();
bool need_new_segment;
if (current_seg == NULL)
need_new_segment = true;
else if (lma - vma != last_lma - last_vma)
{
// This section has a different LMA relationship than the
// last one; we need a new segment.
need_new_segment = true;
}
else if (align_address(last_lma + last_size, abi_pagesize)
< align_address(lma, abi_pagesize))
{
// Putting this section in the segment would require
// skipping a page.
need_new_segment = true;
}
else if (is_bss_section(*plast) && !is_bss_section(*p))
{
// A non-BSS section can not follow a BSS section in the
// same segment.
need_new_segment = true;
}
else if (is_current_seg_readonly
&& ((*p)->flags() & elfcpp::SHF_WRITE) != 0
&& !parameters->options().omagic())
{
// Don't put a writable section in the same segment as a
// non-writable section.
need_new_segment = true;
}
else
{
// Otherwise, reuse the existing segment.
need_new_segment = false;
}
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment((*p)->flags());
if (need_new_segment)
{
current_seg = layout->make_output_segment(elfcpp::PT_LOAD,
seg_flags);
current_seg->set_addresses(vma, lma);
if (first_seg == NULL)
first_seg = current_seg;
is_current_seg_readonly = true;
}
current_seg->add_output_section(*p, seg_flags);
if (((*p)->flags() & elfcpp::SHF_WRITE) != 0)
is_current_seg_readonly = false;
plast = p;
last_vma = vma;
last_lma = lma;
last_size = size;
}
// An ELF program should work even if the program headers are not in
// a PT_LOAD segment. However, it appears that the Linux kernel
// does not set the AT_PHDR auxiliary entry in that case. It sets
// the load address to p_vaddr - p_offset of the first PT_LOAD
// segment. It then sets AT_PHDR to the load address plus the
// offset to the program headers, e_phoff in the file header. This
// fails when the program headers appear in the file before the
// first PT_LOAD segment. Therefore, we always create a PT_LOAD
// segment to hold the file header and the program headers. This is
// effectively what the GNU linker does, and it is slightly more
// efficient in any case. We try to use the first PT_LOAD segment
// if we can, otherwise we make a new one.
if (first_seg == NULL)
return NULL;
// -n or -N mean that the program is not demand paged and there is
// no need to put the program headers in a PT_LOAD segment.
if (parameters->options().nmagic() || parameters->options().omagic())
return NULL;
size_t sizeof_headers = this->total_header_size(layout);
uint64_t vma = first_seg->vaddr();
uint64_t lma = first_seg->paddr();
uint64_t subtract = this->header_size_adjustment(lma, sizeof_headers);
if ((lma & (abi_pagesize - 1)) >= sizeof_headers)
{
first_seg->set_addresses(vma - subtract, lma - subtract);
return first_seg;
}
// If there is no room to squeeze in the headers, then punt. The
// resulting executable probably won't run on GNU/Linux, but we
// trust that the user knows what they are doing.
if (lma < subtract || vma < subtract)
return NULL;
Output_segment* load_seg = layout->make_output_segment(elfcpp::PT_LOAD,
elfcpp::PF_R);
load_seg->set_addresses(vma - subtract, lma - subtract);
return load_seg;
}
// Create a PT_NOTE segment for each SHT_NOTE section and a PT_TLS
// segment if there are any SHT_TLS sections.
void
Script_sections::create_note_and_tls_segments(
Layout* layout,
const Layout::Section_list* sections)
{
gold_assert(!this->saw_phdrs_clause());
bool saw_tls = false;
for (Layout::Section_list::const_iterator p = sections->begin();
p != sections->end();
++p)
{
if ((*p)->type() == elfcpp::SHT_NOTE)
{
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment((*p)->flags());
Output_segment* oseg = layout->make_output_segment(elfcpp::PT_NOTE,
seg_flags);
oseg->add_output_section(*p, seg_flags);
// Incorporate any subsequent SHT_NOTE sections, in the
// hopes that the script is sensible.
Layout::Section_list::const_iterator pnext = p + 1;
while (pnext != sections->end()
&& (*pnext)->type() == elfcpp::SHT_NOTE)
{
seg_flags = Layout::section_flags_to_segment((*pnext)->flags());
oseg->add_output_section(*pnext, seg_flags);
p = pnext;
++pnext;
}
}
if (((*p)->flags() & elfcpp::SHF_TLS) != 0)
{
if (saw_tls)
gold_error(_("TLS sections are not adjacent"));
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment((*p)->flags());
Output_segment* oseg = layout->make_output_segment(elfcpp::PT_TLS,
seg_flags);
oseg->add_output_section(*p, seg_flags);
Layout::Section_list::const_iterator pnext = p + 1;
while (pnext != sections->end()
&& ((*pnext)->flags() & elfcpp::SHF_TLS) != 0)
{
seg_flags = Layout::section_flags_to_segment((*pnext)->flags());
oseg->add_output_section(*pnext, seg_flags);
p = pnext;
++pnext;
}
saw_tls = true;
}
}
}
// Add a program header. The PHDRS clause is syntactically distinct
// from the SECTIONS clause, but we implement it with the SECTIONS
// support becauase PHDRS is useless if there is no SECTIONS clause.
void
Script_sections::add_phdr(const char* name, size_t namelen, unsigned int type,
bool includes_filehdr, bool includes_phdrs,
bool is_flags_valid, unsigned int flags,
Expression* load_address)
{
if (this->phdrs_elements_ == NULL)
this->phdrs_elements_ = new Phdrs_elements();
this->phdrs_elements_->push_back(new Phdrs_element(name, namelen, type,
includes_filehdr,
includes_phdrs,
is_flags_valid, flags,
load_address));
}
// Return the number of segments we expect to create based on the
// SECTIONS clause. This is used to implement SIZEOF_HEADERS.
size_t
Script_sections::expected_segment_count(const Layout* layout) const
{
if (this->saw_phdrs_clause())
return this->phdrs_elements_->size();
Layout::Section_list sections;
layout->get_allocated_sections(&sections);
// We assume that we will need two PT_LOAD segments.
size_t ret = 2;
bool saw_note = false;
bool saw_tls = false;
for (Layout::Section_list::const_iterator p = sections.begin();
p != sections.end();
++p)
{
if ((*p)->type() == elfcpp::SHT_NOTE)
{
// Assume that all note sections will fit into a single
// PT_NOTE segment.
if (!saw_note)
{
++ret;
saw_note = true;
}
}
else if (((*p)->flags() & elfcpp::SHF_TLS) != 0)
{
// There can only be one PT_TLS segment.
if (!saw_tls)
{
++ret;
saw_tls = true;
}
}
}
return ret;
}
// Create the segments from a PHDRS clause. Return the segment which
// should hold the file header and program headers, if any.
Output_segment*
Script_sections::create_segments_from_phdrs_clause(Layout* layout)
{
this->attach_sections_using_phdrs_clause(layout);
return this->set_phdrs_clause_addresses(layout);
}
// Create the segments from the PHDRS clause, and put the output
// sections in them.
void
Script_sections::attach_sections_using_phdrs_clause(Layout* layout)
{
typedef std::map<std::string, Output_segment*> Name_to_segment;
Name_to_segment name_to_segment;
for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
name_to_segment[(*p)->name()] = (*p)->create_segment(layout);
// Walk through the output sections and attach them to segments.
// Output sections in the script which do not list segments are
// attached to the same set of segments as the immediately preceding
// output section.
String_list* phdr_names = NULL;
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
bool orphan;
Output_section* os = (*p)->allocate_to_segment(&phdr_names, &orphan);
if (os == NULL)
continue;
if (phdr_names == NULL)
{
gold_error(_("allocated section not in any segment"));
continue;
}
// If this is an orphan section--one that was not explicitly
// mentioned in the linker script--then it should not inherit
// any segment type other than PT_LOAD. Otherwise, e.g., the
// PT_INTERP segment will pick up following orphan sections,
// which does not make sense. If this is not an orphan section,
// we trust the linker script.
if (orphan)
{
String_list::iterator q = phdr_names->begin();
while (q != phdr_names->end())
{
Name_to_segment::const_iterator r = name_to_segment.find(*q);
// We give errors about unknown segments below.
if (r == name_to_segment.end()
|| r->second->type() == elfcpp::PT_LOAD)
++q;
else
q = phdr_names->erase(q);
}
}
bool in_load_segment = false;
for (String_list::const_iterator q = phdr_names->begin();
q != phdr_names->end();
++q)
{
Name_to_segment::const_iterator r = name_to_segment.find(*q);
if (r == name_to_segment.end())
gold_error(_("no segment %s"), q->c_str());
else
{
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment(os->flags());
r->second->add_output_section(os, seg_flags);
if (r->second->type() == elfcpp::PT_LOAD)
{
if (in_load_segment)
gold_error(_("section in two PT_LOAD segments"));
in_load_segment = true;
}
}
}
if (!in_load_segment)
gold_error(_("allocated section not in any PT_LOAD segment"));
}
}
// Set the addresses for segments created from a PHDRS clause. Return
// the segment which should hold the file header and program headers,
// if any.
Output_segment*
Script_sections::set_phdrs_clause_addresses(Layout* layout)
{
Output_segment* load_seg = NULL;
for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
{
// Note that we have to set the flags after adding the output
// sections to the segment, as adding an output segment can
// change the flags.
(*p)->set_flags_if_valid();
Output_segment* oseg = (*p)->segment();
if (oseg->type() != elfcpp::PT_LOAD)
{
// The addresses of non-PT_LOAD segments are set from the
// PT_LOAD segments.
if ((*p)->has_load_address())
gold_error(_("may only specify load address for PT_LOAD segment"));
continue;
}
// The output sections should have addresses from the SECTIONS
// clause. The addresses don't have to be in order, so find the
// one with the lowest load address. Use that to set the
// address of the segment.
Output_section* osec = oseg->section_with_lowest_load_address();
if (osec == NULL)
{
oseg->set_addresses(0, 0);
continue;
}
uint64_t vma = osec->address();
uint64_t lma = osec->has_load_address() ? osec->load_address() : vma;
// Override the load address of the section with the load
// address specified for the segment.
if ((*p)->has_load_address())
{
if (osec->has_load_address())
gold_warning(_("PHDRS load address overrides "
"section %s load address"),
osec->name());
lma = (*p)->load_address();
}
bool headers = (*p)->includes_filehdr() && (*p)->includes_phdrs();
if (!headers && ((*p)->includes_filehdr() || (*p)->includes_phdrs()))
{
// We could support this if we wanted to.
gold_error(_("using only one of FILEHDR and PHDRS is "
"not currently supported"));
}
if (headers)
{
size_t sizeof_headers = this->total_header_size(layout);
uint64_t subtract = this->header_size_adjustment(lma,
sizeof_headers);
if (lma >= subtract && vma >= subtract)
{
lma -= subtract;
vma -= subtract;
}
else
{
gold_error(_("sections loaded on first page without room "
"for file and program headers "
"are not supported"));
}
if (load_seg != NULL)
gold_error(_("using FILEHDR and PHDRS on more than one "
"PT_LOAD segment is not currently supported"));
load_seg = oseg;
}
oseg->set_addresses(vma, lma);
}
return load_seg;
}
// Add the file header and segment headers to non-load segments
// specified in the PHDRS clause.
void
Script_sections::put_headers_in_phdrs(Output_data* file_header,
Output_data* segment_headers)
{
gold_assert(this->saw_phdrs_clause());
for (Phdrs_elements::iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
{
if ((*p)->type() != elfcpp::PT_LOAD)
{
if ((*p)->includes_phdrs())
(*p)->segment()->add_initial_output_data(segment_headers);
if ((*p)->includes_filehdr())
(*p)->segment()->add_initial_output_data(file_header);
}
}
}
// Look for an output section by name and return the address, the load
// address, the alignment, and the size. This is used when an
// expression refers to an output section which was not actually
// created. This returns true if the section was found, false
// otherwise.
bool
Script_sections::get_output_section_info(const char* name, uint64_t* address,
uint64_t* load_address,
uint64_t* addralign,
uint64_t* size) const
{
if (!this->saw_sections_clause_)
return false;
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
if ((*p)->get_output_section_info(name, address, load_address, addralign,
size))
return true;
return false;
}
// Print the SECTIONS clause to F for debugging.
void
Script_sections::print(FILE* f) const
{
if (!this->saw_sections_clause_)
return;
fprintf(f, "SECTIONS {\n");
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
(*p)->print(f);
fprintf(f, "}\n");
if (this->phdrs_elements_ != NULL)
{
fprintf(f, "PHDRS {\n");
for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
(*p)->print(f);
fprintf(f, "}\n");
}
}
} // End namespace gold.
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