mirror/binutils-gdb
2
0
Fork 0
mirror of https://sourceware.org/git/binutils-gdb.git synced 2024-12-21 04:42:53 +08:00
Code Issues Packages Projects Releases Wiki Activity
c3de4d92df
binutils-gdb/gold/script-sections.cc
Cary Coutant 7c61d651fd Fix problem where script specified both address and region for a section. 
If a script specifies both address and region for an output section
declaration, gold ignores the region specification. This can lead to
bogus "moves backward" errors. This patch fixes gold so that if a
section specifies both address and region, it will place the section
at the specified address in the region, and update the location counter
within the region.

gold/
	PR gold/18847
	* script-sections.cc (Memory_region::set_address): New method.
	(Script_sections::find_memory_region): Add explicit_only parameter.
	(Output_section_definition::set_section_addresses): Handle case where
	script specifies both address and vma region.
	* script-sections.h (Script_sections::find_memory_region): Add
	explicit_only parameter.
2015-08-26 00:03:04 -07:00

4447 lines
123 KiB
C++
Raw Blame History

// script-sections.cc -- linker script SECTIONS for gold
// Copyright (C) 2008-2015 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
{
// A region of memory.
class Memory_region
{
public:
Memory_region(const char* name, size_t namelen, unsigned int attributes,
Expression* start, Expression* length)
: name_(name, namelen),
attributes_(attributes),
start_(start),
length_(length),
current_offset_(0),
vma_sections_(),
lma_sections_(),
last_section_(NULL)
{ }
// Return the name of this region.
const std::string&
name() const
{ return this->name_; }
// Return the start address of this region.
Expression*
start_address() const
{ return this->start_; }
// Return the length of this region.
Expression*
length() const
{ return this->length_; }
// Print the region (when debugging).
void
print(FILE*) const;
// Return true if <name,namelen> matches this region.
bool
name_match(const char* name, size_t namelen)
{
return (this->name_.length() == namelen
&& strncmp(this->name_.c_str(), name, namelen) == 0);
}
Expression*
get_current_address() const
{
return
script_exp_binary_add(this->start_,
script_exp_integer(this->current_offset_));
}
void
set_address(uint64_t addr, const Symbol_table* symtab, const Layout* layout)
{
uint64_t start = this->start_->eval(symtab, layout, false);
uint64_t len = this->length_->eval(symtab, layout, false);
if (addr < start || addr >= start + len)
gold_error(_("address 0x%llx is not within region %s"),
static_cast<unsigned long long>(addr),
this->name_.c_str());
else if (addr < start + this->current_offset_)
gold_error(_("address 0x%llx moves dot backwards in region %s"),
static_cast<unsigned long long>(addr),
this->name_.c_str());
this->current_offset_ = addr - start;
}
void
increment_offset(std::string section_name, uint64_t amount,
const Symbol_table* symtab, const Layout* layout)
{
this->current_offset_ += amount;
if (this->current_offset_
> this->length_->eval(symtab, layout, false))
gold_error(_("section %s overflows end of region %s"),
section_name.c_str(), this->name_.c_str());
}
// Returns true iff there is room left in this region
// for AMOUNT more bytes of data.
bool
has_room_for(const Symbol_table* symtab, const Layout* layout,
uint64_t amount) const
{
return (this->current_offset_ + amount
< this->length_->eval(symtab, layout, false));
}
// Return true if the provided section flags
// are compatible with this region's attributes.
bool
attributes_compatible(elfcpp::Elf_Xword flags, elfcpp::Elf_Xword type) const;
void
add_section(Output_section_definition* sec, bool vma)
{
if (vma)
this->vma_sections_.push_back(sec);
else
this->lma_sections_.push_back(sec);
}
typedef std::vector<Output_section_definition*> Section_list;
// Return the start of the list of sections
// whose VMAs are taken from this region.
Section_list::const_iterator
get_vma_section_list_start() const
{ return this->vma_sections_.begin(); }
// Return the start of the list of sections
// whose LMAs are taken from this region.
Section_list::const_iterator
get_lma_section_list_start() const
{ return this->lma_sections_.begin(); }
// Return the end of the list of sections
// whose VMAs are taken from this region.
Section_list::const_iterator
get_vma_section_list_end() const
{ return this->vma_sections_.end(); }
// Return the end of the list of sections
// whose LMAs are taken from this region.
Section_list::const_iterator
get_lma_section_list_end() const
{ return this->lma_sections_.end(); }
Output_section_definition*
get_last_section() const
{ return this->last_section_; }
void
set_last_section(Output_section_definition* sec)
{ this->last_section_ = sec; }
private:
std::string name_;
unsigned int attributes_;
Expression* start_;
Expression* length_;
// The offset to the next free byte in the region.
// Note - for compatibility with GNU LD we only maintain one offset
// regardless of whether the region is being used for VMA values,
// LMA values, or both.
uint64_t current_offset_;
// A list of sections whose VMAs are set inside this region.
Section_list vma_sections_;
// A list of sections whose LMAs are set inside this region.
Section_list lma_sections_;
// The latest section to make use of this region.
Output_section_definition* last_section_;
};
// Return true if the provided section flags
// are compatible with this region's attributes.
bool
Memory_region::attributes_compatible(elfcpp::Elf_Xword flags,
elfcpp::Elf_Xword type) const
{
unsigned int attrs = this->attributes_;
// No attributes means that this region is not compatible with anything.
if (attrs == 0)
return false;
bool match = true;
do
{
switch (attrs & - attrs)
{
case MEM_EXECUTABLE:
if ((flags & elfcpp::SHF_EXECINSTR) == 0)
match = false;
break;
case MEM_WRITEABLE:
if ((flags & elfcpp::SHF_WRITE) == 0)
match = false;
break;
case MEM_READABLE:
// All sections are presumed readable.
break;
case MEM_ALLOCATABLE:
if ((flags & elfcpp::SHF_ALLOC) == 0)
match = false;
break;
case MEM_INITIALIZED:
if ((type & elfcpp::SHT_NOBITS) != 0)
match = false;
break;
}
attrs &= ~ (attrs & - attrs);
}
while (attrs != 0);
return match;
}
// Print a memory region.
void
Memory_region::print(FILE* f) const
{
fprintf(f, " %s", this->name_.c_str());
unsigned int attrs = this->attributes_;
if (attrs != 0)
{
fprintf(f, " (");
do
{
switch (attrs & - attrs)
{
case MEM_EXECUTABLE: fputc('x', f); break;
case MEM_WRITEABLE: fputc('w', f); break;
case MEM_READABLE: fputc('r', f); break;
case MEM_ALLOCATABLE: fputc('a', f); break;
case MEM_INITIALIZED: fputc('i', f); break;
default:
gold_unreachable();
}
attrs &= ~ (attrs & - attrs);
}
while (attrs != 0);
fputc(')', f);
}
fprintf(f, " : origin = ");
this->start_->print(f);
fprintf(f, ", length = ");
this->length_->print(f);
fprintf(f, "\n");
}
// 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_TLS,
PLACE_TLS_BSS,
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_TLS, NULL);
this->initialize_place(PLACE_TLS_BSS, NULL);
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 ((flags & elfcpp::SHF_TLS) != 0)
{
if (type == elfcpp::SHT_NOBITS)
index = PLACE_TLS_BSS;
else
index = PLACE_TLS;
}
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;
case PLACE_TLS:
follow = PLACE_DATA;
break;
case PLACE_TLS_BSS:
follow = PLACE_TLS;
if (!this->places_[PLACE_TLS].have_location)
follow = PLACE_DATA;
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***,
Script_sections::Section_type*, bool*)
{ 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
// expression is an absolute value.
virtual void
set_section_addresses(Symbol_table*, Layout*, uint64_t*, 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; }
// Set the section's memory regions.
virtual void
set_memory_region(Memory_region*, bool)
{ gold_error(_("Attempt to set a memory region for a non-output section")); }
// 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, false, 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*, uint64_t*)
{
this->assignment_.set_if_absolute(symtab, layout, true, *dot_value, NULL);
}
// 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.
*dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
NULL, NULL, NULL, false);
}
// Update the dot symbol while setting section addresses.
void
set_section_addresses(Symbol_table* symtab, Layout* layout,
uint64_t* dot_value, uint64_t* dot_alignment,
uint64_t* load_address)
{
*dot_value = this->val_->eval_with_dot(symtab, layout, false, *dot_value,
NULL, NULL, dot_alignment, false);
*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<Output_section::Input_section> 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*, bool *) const
{ return false; }
// Set section addresses. This includes applying assignments if the
// expression is an absolute value.
virtual void
set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t,
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, false, 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, uint64_t*,
Output_section** dot_section, std::string*,
Input_section_list*)
{
this->assignment_.set_if_absolute(symtab, layout, true, *dot_value,
*dot_section);
}
// 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)
{ }
// An assignment to dot within an output section is enough to force
// the output section to exist.
bool
needs_output_section() const
{ return true; }
// 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, NULL,
true);
}
// 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, uint64_t*,
Output_section** dot_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,
uint64_t* dot_alignment,
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, dot_alignment,
true);
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);
layout->new_output_section_data_from_script(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, true),
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)
{
uint64_t val = this->val_->eval_with_dot(this->symtab_, this->layout_,
true, this->dot_value_,
this->dot_section_, NULL, NULL,
false);
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, uint64_t*, 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,
uint64_t*,
Output_section** dot_section,
std::string*,
Input_section_list*)
{
gold_assert(os != NULL);
Output_data_expression* expression =
new Output_data_expression(this->size_, this->is_signed_, this->val_,
symtab, layout, *dot_value, *dot_section);
os->add_output_section_data(expression);
layout->new_output_section_data_from_script(expression);
*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, uint64_t*,
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, NULL, false);
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_;
};
// 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.
// If we do then also indicate whether the section should be KEPT.
bool
match_name(const char* file_name, const char* section_name, bool* keep) const;
// Set the section address.
void
set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
uint64_t subalign, uint64_t* dot_value, uint64_t*,
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.c_str())),
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_.c_str());
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).c_str());
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. If we do then
// KEEP indicates whether the section should survive garbage collection.
bool
Output_section_element_input::match_name(const char* file_name,
const char* section_name,
bool *keep) const
{
if (!this->match_file_name(file_name))
return false;
*keep = this->keep_;
// 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.
class Input_section_info
{
public:
Input_section_info(const Output_section::Input_section& input_section)
: input_section_(input_section), section_name_(),
size_(0), addralign_(1)
{ }
// Return the simple input section.
const Output_section::Input_section&
input_section() const
{ return this->input_section_; }
// Return the object.
Relobj*
relobj() const
{ return this->input_section_.relobj(); }
// Return the section index.
unsigned int
shndx()
{ return this->input_section_.shndx(); }
// Return the section name.
const std::string&
section_name() const
{ return this->section_name_; }
// Set the section name.
void
set_section_name(const std::string name)
{
if (is_compressed_debug_section(name.c_str()))
this->section_name_ = corresponding_uncompressed_section_name(name);
else
this->section_name_ = name;
}
// Return the section size.
uint64_t
size() const
{ return this->size_; }
// Set the section size.
void
set_size(uint64_t size)
{ this->size_ = size; }
// Return the address alignment.
uint64_t
addralign() const
{ return this->addralign_; }
// Set the address alignment.
void
set_addralign(uint64_t addralign)
{ this->addralign_ = addralign; }
private:
// Input section, can be a relaxed section.
Output_section::Input_section input_section_;
// Name of the section.
std::string section_name_;
// Section size.
uint64_t size_;
// Address alignment.
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* layout,
Output_section* output_section,
uint64_t subalign,
uint64_t* dot_value,
uint64_t*,
Output_section** dot_section,
std::string* fill,
Input_section_list* input_sections)
{
// We build a list of sections which match each
// Input_section_pattern.
// If none of the patterns specify a sort option, we throw all
// matching input sections into a single bin, in the order we
// find them. Otherwise, we put matching input sections into
// a separate bin for each pattern, and sort each one as
// specified. Thus, an input section spec like this:
// *(.foo .bar)
// will group all .foo and .bar sections in the order seen,
// whereas this:
// *(.foo) *(.bar)
// will group all .foo sections followed by all .bar sections.
// This matches Gnu ld behavior.
// Things get really weird, though, when you add a sort spec
// on some, but not all, of the patterns, like this:
// *(SORT_BY_NAME(.foo) .bar)
// We do not attempt to match Gnu ld behavior in this case.
typedef std::vector<std::vector<Input_section_info> > Matching_sections;
size_t input_pattern_count = this->input_section_patterns_.size();
bool any_patterns_with_sort = false;
for (size_t i = 0; i < input_pattern_count; ++i)
{
const Input_section_pattern& isp(this->input_section_patterns_[i]);
if (isp.sort != SORT_WILDCARD_NONE)
any_patterns_with_sort = true;
}
if (input_pattern_count == 0 || !any_patterns_with_sort)
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())
{
Relobj* relobj = p->relobj();
unsigned int shndx = p->shndx();
Input_section_info isi(*p);
// Calling section_name and section_addralign is not very
// efficient.
// 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, relobj);
isi.set_section_name(relobj->section_name(shndx));
if (p->is_relaxed_input_section())
{
// We use current data size because relaxed section sizes may not
// have finalized yet.
isi.set_size(p->relaxed_input_section()->current_data_size());
isi.set_addralign(p->relaxed_input_section()->addralign());
}
else
{
isi.set_size(relobj->section_size(shndx));
isi.set_addralign(relobj->section_addralign(shndx));
}
}
if (!this->match_file_name(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
{
if (!any_patterns_with_sort)
i = 0;
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.
uint64_t dot = *dot_value;
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)
{
// Override the original address alignment if SUBALIGN is specified
// and is greater than the original alignment. We need to make a
// copy of the input section to modify the alignment.
Output_section::Input_section sis(p->input_section());
uint64_t this_subalign = sis.addralign();
if (!sis.is_input_section())
sis.output_section_data()->finalize_data_size();
uint64_t data_size = sis.data_size();
if (this_subalign < subalign)
{
this_subalign = subalign;
sis.set_addralign(subalign);
}
uint64_t address = align_address(dot, this_subalign);
if (address > dot && !fill->empty())
{
section_size_type length =
convert_to_section_size_type(address - dot);
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);
layout->new_output_section_data_from_script(posd);
}
output_section->add_script_input_section(sis);
dot = address + data_size;
}
}
// An SHF_TLS/SHT_NOBITS section does not take up any
// address space.
if (output_section == NULL
|| (output_section->flags() & elfcpp::SHF_TLS) == 0
|| output_section->type() != elfcpp::SHT_NOBITS)
*dot_value = dot;
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***, Script_sections::Section_type*,
bool*);
// 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*,
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;
// Return the output section type if specified or Script_sections::ST_NONE.
Script_sections::Section_type
section_type() const;
// Store the memory region to use.
void
set_memory_region(Memory_region*, bool set_vma);
void
set_section_vma(Expression* address)
{ this->address_ = address; }
void
set_section_lma(Expression* address)
{ this->load_address_ = address; }
const std::string&
get_section_name() const
{ return this->name_; }
private:
static const char*
script_section_type_name(Script_section_type);
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_;
// The output section type if specified.
enum Script_section_type script_section_type_;
};
// 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),
script_section_type_(header->section_type)
{
}
// 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, this->section_type());
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)
{
address = this->address_->eval_with_dot(symtab, layout, true,
*dot_value, NULL,
NULL, NULL, false);
}
if (this->align_ != NULL)
{
uint64_t align = this->align_->eval_with_dot(symtab, layout, true,
*dot_value, NULL,
NULL, NULL, false);
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,
Script_sections::Section_type* psection_type,
bool* keep)
{
// 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, keep))
{
// We found a match for NAME, which means that it should go
// into this output section.
*slot = &this->output_section_;
*psection_type = this->section_type();
return this->name_.c_str();
}
}
// We don't know about this section name.
return NULL;
}
// Return true if memory from START to START + LENGTH is contained
// within a memory region.
bool
Script_sections::block_in_region(Symbol_table* symtab, Layout* layout,
uint64_t start, uint64_t length) const
{
if (this->memory_regions_ == NULL)
return false;
for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
mr != this->memory_regions_->end();
++mr)
{
uint64_t s = (*mr)->start_address()->eval(symtab, layout, false);
uint64_t l = (*mr)->length()->eval(symtab, layout, false);
if (s <= start
&& (s + l) >= (start + length))
return true;
}
return false;
}
// Find a memory region that should be used by a given output SECTION.
// If provided set PREVIOUS_SECTION_RETURN to point to the last section
// that used the return memory region.
Memory_region*
Script_sections::find_memory_region(
Output_section_definition* section,
bool find_vma_region,
bool explicit_only,
Output_section_definition** previous_section_return)
{
if (previous_section_return != NULL)
* previous_section_return = NULL;
// Walk the memory regions specified in this script, if any.
if (this->memory_regions_ == NULL)
return NULL;
// The /DISCARD/ section never gets assigned to any region.
if (section->get_section_name() == "/DISCARD/")
return NULL;
Memory_region* first_match = NULL;
// First check to see if a region has been assigned to this section.
for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
mr != this->memory_regions_->end();
++mr)
{
if (find_vma_region)
{
for (Memory_region::Section_list::const_iterator s =
(*mr)->get_vma_section_list_start();
s != (*mr)->get_vma_section_list_end();
++s)
if ((*s) == section)
{
(*mr)->set_last_section(section);
return *mr;
}
}
else
{
for (Memory_region::Section_list::const_iterator s =
(*mr)->get_lma_section_list_start();
s != (*mr)->get_lma_section_list_end();
++s)
if ((*s) == section)
{
(*mr)->set_last_section(section);
return *mr;
}
}
if (!explicit_only)
{
// Make a note of the first memory region whose attributes
// are compatible with the section. If we do not find an
// explicit region assignment, then we will return this region.
Output_section* out_sec = section->get_output_section();
if (first_match == NULL
&& out_sec != NULL
&& (*mr)->attributes_compatible(out_sec->flags(),
out_sec->type()))
first_match = *mr;
}
}
// With LMA computations, if an explicit region has not been specified then
// we will want to set the difference between the VMA and the LMA of the
// section were searching for to be the same as the difference between the
// VMA and LMA of the last section to be added to first matched region.
// Hence, if it was asked for, we return a pointer to the last section
// known to be used by the first matched region.
if (first_match != NULL
&& previous_section_return != NULL)
*previous_section_return = first_match->get_last_section();
return first_match;
}
// 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* dot_alignment,
uint64_t* load_address)
{
Memory_region* vma_region = NULL;
Memory_region* lma_region = NULL;
Script_sections* script_sections =
layout->script_options()->script_sections();
uint64_t address;
uint64_t old_dot_value = *dot_value;
uint64_t old_load_address = *load_address;
// If input section sorting is requested via --section-ordering-file or
// linker plugins, then do it here. This is important because we want
// any sorting specified in the linker scripts, which will be done after
// this, to take precedence. The final order of input sections is then
// guaranteed to be according to the linker script specification.
if (this->output_section_ != NULL
&& this->output_section_->input_section_order_specified())
this->output_section_->sort_attached_input_sections();
// Decide the start address for the section. The algorithm is:
// 1) If an address has been specified in a linker script, use that.
// 2) Otherwise if a memory region has been specified for the section,
// use the next free address in the region.
// 3) Otherwise if memory regions have been specified find the first
// region whose attributes are compatible with this section and
// install it into that region.
// 4) Otherwise use the current location counter.
if (this->output_section_ != NULL
// Check for --section-start.
&& parameters->options().section_start(this->output_section_->name(),
&address))
;
else if (this->address_ == NULL)
{
vma_region = script_sections->find_memory_region(this, true, false, NULL);
if (vma_region != NULL)
address = vma_region->get_current_address()->eval(symtab, layout,
false);
else
address = *dot_value;
}
else
{
vma_region = script_sections->find_memory_region(this, true, true, NULL);
address = this->address_->eval_with_dot(symtab, layout, true,
*dot_value, NULL, NULL,
dot_alignment, false);
if (vma_region != NULL)
vma_region->set_address(address, symtab, layout);
}
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, NULL, false);
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;
// Except for NOLOAD sections, 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_->is_noload()))
this->output_section_->set_address(address);
this->evaluated_address_ = address;
this->evaluated_addralign_ = align;
uint64_t laddr;
if (this->load_address_ == NULL)
{
Output_section_definition* previous_section;
// Determine if an LMA region has been set for this section.
lma_region = script_sections->find_memory_region(this, false, false,
&previous_section);
if (lma_region != NULL)
{
if (previous_section == NULL)
// The LMA address was explicitly set to the given region.
laddr = lma_region->get_current_address()->eval(symtab, layout,
false);
else
{
// We are not going to use the discovered lma_region, so
// make sure that we do not update it in the code below.
lma_region = NULL;
if (this->address_ != NULL || previous_section == this)
{
// Either an explicit VMA address has been set, or an
// explicit VMA region has been set, so set the LMA equal to
// the VMA.
laddr = address;
}
else
{
// The LMA address was not explicitly or implicitly set.
//
// We have been given the first memory region that is
// compatible with the current section and a pointer to the
// last section to use this region. Set the LMA of this
// section so that the difference between its' VMA and LMA
// is the same as the difference between the VMA and LMA of
// the last section in the given region.
laddr = address + (previous_section->evaluated_load_address_
- previous_section->evaluated_address_);
}
}
if (this->output_section_ != NULL)
this->output_section_->set_load_address(laddr);
}
else
{
// Do not set the load address of the output section, if one exists.
// This allows future sections to determine what the load address
// should be. If none is ever set, it will default to being the
// same as the vma address.
laddr = address;
}
}
else
{
laddr = this->load_address_->eval_with_dot(symtab, layout, true,
*dot_value,
this->output_section_,
NULL, NULL, false);
if (this->output_section_ != NULL)
this->output_section_->set_load_address(laddr);
}
this->evaluated_load_address_ = laddr;
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, NULL,
false);
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,
NULL, false);
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_alignment,
&dot_section, &fill, &input_sections);
gold_assert(input_sections.empty());
if (vma_region != NULL)
{
// Update the VMA region being used by the section now that we know how
// big it is. Use the current address in the region, rather than
// start_address because that might have been aligned upwards and we
// need to allow for the padding.
Expression* addr = vma_region->get_current_address();
uint64_t size = *dot_value - addr->eval(symtab, layout, false);
vma_region->increment_offset(this->get_section_name(), size,
symtab, layout);
}
// If the LMA region is different from the VMA region, then increment the
// offset there as well. Note that we use the same "dot_value -
// start_address" formula that is used in the load_address assignment below.
if (lma_region != NULL && lma_region != vma_region)
lma_region->increment_offset(this->get_section_name(),
*dot_value - start_address,
symtab, layout);
// Compute the load address for the following section.
if (this->output_section_ == NULL)
*load_address = *dot_value;
else if (this->load_address_ == NULL)
{
if (lma_region == NULL)
*load_address = *dot_value;
else
*load_address =
lma_region->get_current_address()->eval(symtab, layout, false);
}
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();
// If this is a NOLOAD section, keep dot and load address unchanged.
if (this->output_section_->is_noload())
{
*dot_value = old_dot_value;
*load_address = old_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
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)
{
// Update phdrs_list even if we don't have an output section. It
// might be used by the following sections.
if (this->phdrs_ != NULL)
*phdrs_list = this->phdrs_;
if (this->output_section_ == NULL)
return NULL;
if ((this->output_section_->flags() & elfcpp::SHF_ALLOC) == 0)
return NULL;
*orphan = false;
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, " ");
}
if (this->script_section_type_ != SCRIPT_SECTION_TYPE_NONE)
fprintf(f, "(%s) ",
this->script_section_type_name(this->script_section_type_));
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");
}
Script_sections::Section_type
Output_section_definition::section_type() const
{
switch (this->script_section_type_)
{
case SCRIPT_SECTION_TYPE_NONE:
return Script_sections::ST_NONE;
case SCRIPT_SECTION_TYPE_NOLOAD:
return Script_sections::ST_NOLOAD;
case SCRIPT_SECTION_TYPE_COPY:
case SCRIPT_SECTION_TYPE_DSECT:
case SCRIPT_SECTION_TYPE_INFO:
case SCRIPT_SECTION_TYPE_OVERLAY:
// There are not really support so we treat them as ST_NONE. The
// parse should have issued errors for them already.
return Script_sections::ST_NONE;
default:
gold_unreachable();
}
}
// Return the name of a script section type.
const char*
Output_section_definition::script_section_type_name(
Script_section_type script_section_type)
{
switch (script_section_type)
{
case SCRIPT_SECTION_TYPE_NONE:
return "NONE";
case SCRIPT_SECTION_TYPE_NOLOAD:
return "NOLOAD";
case SCRIPT_SECTION_TYPE_DSECT:
return "DSECT";
case SCRIPT_SECTION_TYPE_COPY:
return "COPY";
case SCRIPT_SECTION_TYPE_INFO:
return "INFO";
case SCRIPT_SECTION_TYPE_OVERLAY:
return "OVERLAY";
default:
gold_unreachable();
}
}
void
Output_section_definition::set_memory_region(Memory_region* mr, bool set_vma)
{
gold_assert(mr != NULL);
// Add the current section to the specified region's list.
mr->add_section(this, set_vma);
}
// 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*,
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*,
uint64_t* load_address)
{
typedef std::list<Output_section::Input_section> Input_section_list;
bool have_load_address = *load_address != *dot_value;
uint64_t address = *dot_value;
address = align_address(address, this->os_->addralign());
// If input section sorting is requested via --section-ordering-file or
// linker plugins, then do it here. This is important because we want
// any sorting specified in the linker scripts, which will be done after
// this, to take precedence. The final order of input sections is then
// guaranteed to be according to the linker script specification.
if (this->os_ != NULL
&& this->os_->input_section_order_specified())
this->os_->sort_attached_input_sections();
// For a relocatable link, all orphan sections are put at
// address 0. In general we expect all sections to be at
// address 0 for a relocatable link, but we permit the linker
// script to override that for specific output sections.
if (parameters->options().relocatable())
{
address = 0;
*load_address = 0;
have_load_address = false;
}
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 = p->addralign();
if (!p->is_input_section())
p->output_section_data()->finalize_data_size();
uint64_t size = p->data_size();
address = align_address(address, addralign);
this->os_->add_script_input_section(*p);
address += size;
}
if (parameters->options().relocatable())
{
// For a relocatable link, reset DOT_VALUE to 0.
*dot_value = 0;
*load_address = 0;
}
else if (this->os_ == NULL
|| (this->os_->flags() & elfcpp::SHF_TLS) == 0
|| this->os_->type() != elfcpp::SHT_NOBITS)
{
// An SHF_TLS/SHT_NOBITS section does not take up any address space.
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_; }
// Release the segment.
void
release_segment()
{ this->segment_ = NULL; }
// 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");
}
// Add a memory region.
void
Script_sections::add_memory_region(const char* name, size_t namelen,
unsigned int attributes,
Expression* start, Expression* length)
{
if (this->memory_regions_ == NULL)
this->memory_regions_ = new Memory_regions();
else if (this->find_memory_region(name, namelen))
{
gold_error(_("region '%.*s' already defined"), static_cast<int>(namelen),
name);
// FIXME: Add a GOLD extension to allow multiple regions with the same
// name. This would amount to a single region covering disjoint blocks
// of memory, which is useful for embedded devices.
}
// FIXME: Check the length and start values. Currently we allow
// non-constant expressions for these values, whereas LD does not.
// FIXME: Add a GOLD extension to allow NEGATIVE LENGTHS. This would
// describe a region that packs from the end address going down, rather
// than the start address going up. This would be useful for embedded
// devices.
this->memory_regions_->push_back(new Memory_region(name, namelen, attributes,
start, length));
}
// Find a memory region.
Memory_region*
Script_sections::find_memory_region(const char* name, size_t namelen)
{
if (this->memory_regions_ == NULL)
return NULL;
for (Memory_regions::const_iterator m = this->memory_regions_->begin();
m != this->memory_regions_->end();
++m)
if ((*m)->name_match(name, namelen))
return *m;
return NULL;
}
// Find a memory region's origin.
Expression*
Script_sections::find_memory_region_origin(const char* name, size_t namelen)
{
Memory_region* mr = find_memory_region(name, namelen);
if (mr == NULL)
return NULL;
return mr->start_address();
}
// Find a memory region's length.
Expression*
Script_sections::find_memory_region_length(const char* name, size_t namelen)
{
Memory_region* mr = find_memory_region(name, namelen);
if (mr == NULL)
return NULL;
return mr->length();
}
// Set the memory region to use for the current section.
void
Script_sections::set_memory_region(Memory_region* mr, bool set_vma)
{
gold_assert(!this->sections_elements_->empty());
this->sections_elements_->back()->set_memory_region(mr, set_vma);
}
// Class Script_sections.
Script_sections::Script_sections()
: saw_sections_clause_(false),
in_sections_clause_(false),
sections_elements_(NULL),
output_section_(NULL),
memory_regions_(NULL),
phdrs_elements_(NULL),
orphan_section_placement_(NULL),
data_segment_align_start_(),
saw_data_segment_align_(false),
saw_relro_end_(false),
saw_segment_start_expression_(false),
segments_created_(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
{
// The GNU linker permits assignments to . to appears outside of
// a SECTIONS clause, and treats it as appearing inside, so
// sections_elements_ may be NULL here.
if (this->sections_elements_ == NULL)
{
this->sections_elements_ = new Sections_elements;
this->saw_sections_clause_ = true;
}
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,
Script_sections::Section_type* psection_type,
bool* keep)
{
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,
psection_type, keep);
if (ret != NULL)
{
// The special name /DISCARD/ means that the input section
// should be discarded.
if (strcmp(ret, "/DISCARD/") == 0)
{
*output_section_slot = NULL;
*psection_type = Script_sections::ST_NONE;
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;
*psection_type = Script_sections::ST_NONE;
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 dot_alignment = 0;
uint64_t load_address = 0;
// Check to see if we want to use any of -Ttext, -Tdata and -Tbss options
// to set section addresses. If the script has any SEGMENT_START
// expression, we do not set the section addresses.
bool use_tsection_options =
(!this->saw_segment_start_expression_
&& (parameters->options().user_set_Ttext()
|| parameters->options().user_set_Tdata()
|| parameters->options().user_set_Tbss()));
for (Sections_elements::iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
Output_section* os = (*p)->get_output_section();
// Handle -Ttext, -Tdata and -Tbss options. We do this by looking for
// the special sections by names and doing dot assignments.
if (use_tsection_options
&& os != NULL
&& (os->flags() & elfcpp::SHF_ALLOC) != 0)
{
uint64_t new_dot_value = dot_value;
if (parameters->options().user_set_Ttext()
&& strcmp(os->name(), ".text") == 0)
new_dot_value = parameters->options().Ttext();
else if (parameters->options().user_set_Tdata()
&& strcmp(os->name(), ".data") == 0)
new_dot_value = parameters->options().Tdata();
else if (parameters->options().user_set_Tbss()
&& strcmp(os->name(), ".bss") == 0)
new_dot_value = parameters->options().Tbss();
// Update dot and load address if necessary.
if (new_dot_value < dot_value)
gold_error(_("dot may not move backward"));
else if (new_dot_value != dot_value)
{
dot_value = new_dot_value;
load_address = new_dot_value;
}
}
(*p)->set_section_addresses(symtab, layout, &dot_value, &dot_alignment,
&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, dot_alignment);
}
// Sort the sections in order to put them into segments.
class Sort_output_sections
{
public:
Sort_output_sections(const Script_sections::Sections_elements* elements)
: elements_(elements)
{ }
bool
operator()(const Output_section* os1, const Output_section* os2) const;
private:
int
script_compare(const Output_section* os1, const Output_section* os2) const;
private:
const Script_sections::Sections_elements* elements_;
};
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();
// If the linker script says which of these sections is first, go
// with what it says.
int i = this->script_compare(os1, os2);
if (i != 0)
return i < 0;
// Sort PROGBITS before NOBITS.
bool nobits1 = os1->type() == elfcpp::SHT_NOBITS;
bool nobits2 = os2->type() == elfcpp::SHT_NOBITS;
if (nobits1 != nobits2)
return nobits2;
// Sort PROGBITS TLS sections to the end, NOBITS TLS sections to the
// beginning.
bool tls1 = (os1->flags() & elfcpp::SHF_TLS) != 0;
bool tls2 = (os2->flags() & elfcpp::SHF_TLS) != 0;
if (tls1 != tls2)
return nobits1 ? tls1 : tls2;
// Sort non-NOLOAD before NOLOAD.
if (os1->is_noload() && !os2->is_noload())
return true;
if (!os1->is_noload() && os2->is_noload())
return true;
// The sections seem practically identical. Sort by name to get a
// stable sort.
return os1->name() < os2->name();
}
// Return -1 if OS1 comes before OS2 in ELEMENTS_, 1 if comes after, 0
// if either OS1 or OS2 is not mentioned. This ensures that we keep
// empty sections in the order in which they appear in a linker
// script.
int
Sort_output_sections::script_compare(const Output_section* os1,
const Output_section* os2) const
{
if (this->elements_ == NULL)
return 0;
bool found_os1 = false;
bool found_os2 = false;
for (Script_sections::Sections_elements::const_iterator
p = this->elements_->begin();
p != this->elements_->end();
++p)
{
if (os2 == (*p)->get_output_section())
{
if (found_os1)
return -1;
found_os2 = true;
}
else if (os1 == (*p)->get_output_section())
{
if (found_os2)
return 1;
found_os1 = true;
}
}
return 0;
}
// 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 accommodate
// 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, uint64_t dot_alignment)
{
gold_assert(this->saw_sections_clause_);
if (parameters->options().relocatable())
return NULL;
if (this->saw_phdrs_clause())
return create_segments_from_phdrs_clause(layout, dot_alignment);
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->sections_elements_));
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);
current_seg->set_minimum_p_align(dot_alignment);
if (first_seg == NULL)
first_seg = current_seg;
is_current_seg_readonly = true;
}
current_seg->add_output_section_to_load(layout, *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;
// If memory regions have been specified and the address range
// we are about to use is not contained within any region then
// issue a warning message about the segment we are going to
// create. It will be outside of any region and so possibly
// using non-existent or protected memory. We test LMA rather
// than VMA since we assume that the headers will never be
// relocated.
if (this->memory_regions_ != NULL
&& !this->block_in_region (NULL, layout, lma - subtract, subtract))
gold_warning(_("creating a segment to contain the file and program"
" headers outside of any MEMORY region"));
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_to_nonload(*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_to_nonload(*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_to_nonload(*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_to_nonload(*pnext, seg_flags);
p = pnext;
++pnext;
}
saw_tls = true;
}
// If we see a section named .interp then put the .interp section
// in a PT_INTERP segment.
// This is for GNU ld compatibility.
if (strcmp((*p)->name(), ".interp") == 0)
{
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment((*p)->flags());
Output_segment* oseg = layout->make_output_segment(elfcpp::PT_INTERP,
seg_flags);
oseg->add_output_section_to_nonload(*p, seg_flags);
}
}
this->segments_created_ = true;
}
// Add a program header. The PHDRS clause is syntactically distinct
// from the SECTIONS clause, but we implement it with the SECTIONS
// support because 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 we've already created the segments, we won't be adding any more.
if (this->segments_created_)
return 0;
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;
bool saw_interp = 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;
}
}
else if (strcmp((*p)->name(), ".interp") == 0)
{
// There can only be one PT_INTERP segment.
if (!saw_interp)
{
++ret;
saw_interp = 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,
uint64_t dot_alignment)
{
this->attach_sections_using_phdrs_clause(layout);
return this->set_phdrs_clause_addresses(layout, dot_alignment);
}
// 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);
this->segments_created_ = true;
// 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;
bool load_segments_only = false;
for (Sections_elements::const_iterator p = this->sections_elements_->begin();
p != this->sections_elements_->end();
++p)
{
bool is_orphan;
String_list* old_phdr_names = phdr_names;
Output_section* os = (*p)->allocate_to_segment(&phdr_names, &is_orphan);
if (os == NULL)
continue;
elfcpp::Elf_Word seg_flags =
Layout::section_flags_to_segment(os->flags());
if (phdr_names == NULL)
{
// Don't worry about empty orphan sections.
if (is_orphan && os->current_data_size() > 0)
gold_error(_("allocated section %s not in any segment"),
os->name());
// To avoid later crashes drop this section into the first
// PT_LOAD segment.
for (Phdrs_elements::const_iterator ppe =
this->phdrs_elements_->begin();
ppe != this->phdrs_elements_->end();
++ppe)
{
Output_segment* oseg = (*ppe)->segment();
if (oseg->type() == elfcpp::PT_LOAD)
{
oseg->add_output_section_to_load(layout, os, seg_flags);
break;
}
}
continue;
}
// We see a list of segments names. Disable PT_LOAD segment only
// filtering.
if (old_phdr_names != phdr_names)
load_segments_only = false;
// 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 (is_orphan)
{
// Enable PT_LOAD segments only filtering until we see another
// list of segment names.
load_segments_only = true;
}
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
{
if (load_segments_only
&& r->second->type() != elfcpp::PT_LOAD)
continue;
if (r->second->type() != elfcpp::PT_LOAD)
r->second->add_output_section_to_nonload(os, seg_flags);
else
{
r->second->add_output_section_to_load(layout, os, seg_flags);
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,
uint64_t dot_alignment)
{
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;
}
oseg->set_minimum_p_align(dot_alignment);
// 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;
}
// Release all Output_segments. This remove all pointers to all
// Output_segments.
void
Script_sections::release_segments()
{
if (this->saw_phdrs_clause())
{
for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin();
p != this->phdrs_elements_->end();
++p)
(*p)->release_segment();
}
}
// Print the SECTIONS clause to F for debugging.
void
Script_sections::print(FILE* f) const
{
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");
}
if (this->memory_regions_ != NULL)
{
fprintf(f, "MEMORY {\n");
for (Memory_regions::const_iterator m = this->memory_regions_->begin();
m != this->memory_regions_->end();
++m)
(*m)->print(f);
fprintf(f, "}\n");
}
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");
}
} // End namespace gold.
Reference in New Issue View Git Blame Copy Permalink