diff options
| -rw-r--r-- | gold/ChangeLog | 23 | ||||
| -rw-r--r-- | gold/script-sections.cc | 513 | ||||
| -rw-r--r-- | gold/script-sections.h | 22 |
3 files changed, 376 insertions, 182 deletions
diff --git a/gold/ChangeLog b/gold/ChangeLog index 5e19718..9dd8787 100644 --- a/gold/ChangeLog +++ b/gold/ChangeLog @@ -1,3 +1,26 @@ +2009-03-18 Ian Lance Taylor <iant@google.com> + + * script-sections.h: Include <list>. + (class Script_sections): Change Sections_elements from std::vector + to std::list. Typedef public Elements_iterator. Add + orphan_section_placement_, data_segment_align_start_, and + saw_data_segment_align_ fields. Remove data_segment_align_index_ + field. + * script-sections.cc (class Orphan_section_placement): New class. + (class Sections_element): Add virtual functions is_relro and + orphan_section_init. Remove virtual function place_orphan_here. + (class Output_section_definition): Add is_relro and + orphan_section_init. Remove place_orphan_here. + (class Orphan_output_section): Likewise. + (Script_sections::Script_sections): Update for field changes. + (Script_sections::data_segment_align): Set saw_data_segment_align_ + and data_segment_align_start_, not data_segment_align_index. + (Script_sections::data_segment_relro_end): Check + saw_data_segment_align_. Use data_segment_align_start_ rather + than data_segment_align_index_. + (Script_sections::place_orphan): Rewrite to use + Orphan_section_placement. + 2009-03-17 Ian Lance Taylor <iant@google.com> * archive.cc (Archive::add_symbols): Check for a version attached diff --git a/gold/script-sections.cc b/gold/script-sections.cc index 990a1a2..9daf9ec 100644 --- a/gold/script-sections.cc +++ b/gold/script-sections.cc @@ -1,6 +1,6 @@ // script-sections.cc -- linker script SECTIONS for gold -// Copyright 2008 Free Software Foundation, Inc. +// Copyright 2008, 2009 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. @@ -43,6 +43,259 @@ namespace gold { +// Manage orphan sections. This is intended to be largely compatible +// with the GNU linker. The Linux kernel implicitly relies on +// something similar to the GNU linker's orphan placement. We +// originally used a simpler scheme here, but it caused the kernel +// build to fail, and was also rather inefficient. + +class Orphan_section_placement +{ + private: + typedef Script_sections::Elements_iterator Elements_iterator; + + public: + Orphan_section_placement(); + + // Handle an output section during initialization of this mapping. + void + output_section_init(const std::string& name, Output_section*, + Elements_iterator location); + + // Initialize the last location. + void + last_init(Elements_iterator location); + + // Set *PWHERE to the address of an iterator pointing to the + // location to use for an orphan section. Return true if the + // iterator has a value, false otherwise. + bool + find_place(Output_section*, Elements_iterator** pwhere); + + // Return the iterator being used for sections at the very end of + // the linker script. + Elements_iterator + last_place() const; + + private: + // The places that we specifically recognize. This list is copied + // from the GNU linker. + enum Place_index + { + PLACE_TEXT, + PLACE_RODATA, + PLACE_DATA, + PLACE_BSS, + PLACE_REL, + PLACE_INTERP, + PLACE_NONALLOC, + PLACE_LAST, + PLACE_MAX + }; + + // The information we keep for a specific place. + struct Place + { + // The name of sections for this place. + const char* name; + // Whether we have a location for this place. + bool have_location; + // The iterator for this place. + Elements_iterator location; + }; + + // Initialize one place element. + void + initialize_place(Place_index, const char*); + + // The places. + Place places_[PLACE_MAX]; + // True if this is the first call to output_section_init. + bool first_init_; +}; + +// Initialize Orphan_section_placement. + +Orphan_section_placement::Orphan_section_placement() + : first_init_(true) +{ + this->initialize_place(PLACE_TEXT, ".text"); + this->initialize_place(PLACE_RODATA, ".rodata"); + this->initialize_place(PLACE_DATA, ".data"); + this->initialize_place(PLACE_BSS, ".bss"); + this->initialize_place(PLACE_REL, NULL); + this->initialize_place(PLACE_INTERP, ".interp"); + this->initialize_place(PLACE_NONALLOC, NULL); + this->initialize_place(PLACE_LAST, NULL); +} + +// Initialize one place element. + +void +Orphan_section_placement::initialize_place(Place_index index, const char* name) +{ + this->places_[index].name = name; + this->places_[index].have_location = false; +} + +// While initializing the Orphan_section_placement information, this +// is called once for each output section named in the linker script. +// If we found an output section during the link, it will be passed in +// OS. + +void +Orphan_section_placement::output_section_init(const std::string& name, + Output_section* os, + Elements_iterator location) +{ + bool first_init = this->first_init_; + this->first_init_ = false; + + for (int i = 0; i < PLACE_MAX; ++i) + { + if (this->places_[i].name != NULL && this->places_[i].name == name) + { + if (this->places_[i].have_location) + { + // We have already seen a section with this name. + return; + } + + this->places_[i].location = location; + this->places_[i].have_location = true; + + // If we just found the .bss section, restart the search for + // an unallocated section. This follows the GNU linker's + // behaviour. + if (i == PLACE_BSS) + this->places_[PLACE_NONALLOC].have_location = false; + + return; + } + } + + // Relocation sections. + if (!this->places_[PLACE_REL].have_location + && os != NULL + && (os->type() == elfcpp::SHT_REL || os->type() == elfcpp::SHT_RELA) + && (os->flags() & elfcpp::SHF_ALLOC) != 0) + { + this->places_[PLACE_REL].location = location; + this->places_[PLACE_REL].have_location = true; + } + + // We find the location for unallocated sections by finding the + // first debugging or comment section after the BSS section (if + // there is one). + if (!this->places_[PLACE_NONALLOC].have_location + && (name == ".comment" || Layout::is_debug_info_section(name.c_str()))) + { + // We add orphan sections after the location in PLACES_. We + // want to store unallocated sections before LOCATION. If this + // is the very first section, we can't use it. + if (!first_init) + { + --location; + this->places_[PLACE_NONALLOC].location = location; + this->places_[PLACE_NONALLOC].have_location = true; + } + } +} + +// Initialize the last location. + +void +Orphan_section_placement::last_init(Elements_iterator location) +{ + this->places_[PLACE_LAST].location = location; + this->places_[PLACE_LAST].have_location = true; +} + +// Set *PWHERE to the address of an iterator pointing to the location +// to use for an orphan section. Return true if the iterator has a +// value, false otherwise. + +bool +Orphan_section_placement::find_place(Output_section* os, + Elements_iterator** pwhere) +{ + // Figure out where OS should go. This is based on the GNU linker + // code. FIXME: The GNU linker handles small data sections + // specially, but we don't. + elfcpp::Elf_Word type = os->type(); + elfcpp::Elf_Xword flags = os->flags(); + Place_index index; + if ((flags & elfcpp::SHF_ALLOC) == 0 + && !Layout::is_debug_info_section(os->name())) + index = PLACE_NONALLOC; + else if ((flags & elfcpp::SHF_ALLOC) == 0) + index = PLACE_LAST; + else if (type == elfcpp::SHT_NOTE) + index = PLACE_INTERP; + else if (type == elfcpp::SHT_NOBITS) + index = PLACE_BSS; + else if ((flags & elfcpp::SHF_WRITE) != 0) + index = PLACE_DATA; + else if (type == elfcpp::SHT_REL || type == elfcpp::SHT_RELA) + index = PLACE_REL; + else if ((flags & elfcpp::SHF_EXECINSTR) == 0) + index = PLACE_RODATA; + else + index = PLACE_TEXT; + + // If we don't have a location yet, try to find one based on a + // plausible ordering of sections. + if (!this->places_[index].have_location) + { + Place_index follow; + switch (index) + { + default: + follow = PLACE_MAX; + break; + case PLACE_RODATA: + follow = PLACE_TEXT; + break; + case PLACE_BSS: + follow = PLACE_DATA; + break; + case PLACE_REL: + follow = PLACE_TEXT; + break; + case PLACE_INTERP: + follow = PLACE_TEXT; + break; + } + if (follow != PLACE_MAX && this->places_[follow].have_location) + { + // Set the location of INDEX to the location of FOLLOW. The + // location of INDEX will then be incremented by the caller, + // so anything in INDEX will continue to be after anything + // in FOLLOW. + this->places_[index].location = this->places_[follow].location; + this->places_[index].have_location = true; + } + } + + *pwhere = &this->places_[index].location; + bool ret = this->places_[index].have_location; + + // The caller will set the location. + this->places_[index].have_location = true; + + return ret; +} + +// Return the iterator being used for sections at the very end of the +// linker script. + +Orphan_section_placement::Elements_iterator +Orphan_section_placement::last_place() const +{ + gold_assert(this->places_[PLACE_LAST].have_location); + return this->places_[PLACE_LAST].location; +} + // An element in a SECTIONS clause. class Sections_element @@ -54,6 +307,11 @@ class 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() @@ -82,11 +340,11 @@ class Sections_element output_section_name(const char*, const char*, Output_section***) { return NULL; } - // Return whether to place an orphan output section after this - // element. - virtual bool - place_orphan_here(const Output_section *, bool*, bool*) const - { return false; } + // Initialize OSP with an output section. + virtual void + orphan_section_init(Orphan_section_placement*, + Script_sections::Elements_iterator) + { } // Set section addresses. This includes applying assignments if the // the expression is an absolute value. @@ -1241,6 +1499,11 @@ class Output_section_definition : public Sections_element 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() @@ -1264,9 +1527,11 @@ class Output_section_definition : public Sections_element output_section_name(const char* file_name, const char* section_name, Output_section***); - // Return whether to place an orphan section after this one. - bool - place_orphan_here(const Output_section *os, bool* exact, bool*) const; + // 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 @@ -1538,124 +1803,6 @@ Output_section_definition::output_section_name(const char* file_name, return NULL; } -// Return whether to place an orphan output section after this -// section. - -bool -Output_section_definition::place_orphan_here(const Output_section *os, - bool* exact, - bool* is_relro) const -{ - *is_relro = this->is_relro_; - - // Check for the simple case first. - if (this->output_section_ != NULL - && this->output_section_->type() == os->type() - && this->output_section_->flags() == os->flags()) - { - *exact = true; - return true; - } - - // Otherwise use some heuristics. - - if ((os->flags() & elfcpp::SHF_ALLOC) == 0) - return false; - - if (os->type() == elfcpp::SHT_NOBITS) - { - if (this->name_ == ".bss") - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_NOBITS) - return true; - } - else if (os->type() == elfcpp::SHT_NOTE) - { - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_NOTE) - { - *exact = true; - return true; - } - if (this->name_.compare(0, 5, ".note") == 0) - { - *exact = true; - return true; - } - if (this->name_ == ".interp") - return true; - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_PROGBITS - && (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0) - return true; - } - else if (os->type() == elfcpp::SHT_REL || os->type() == elfcpp::SHT_RELA) - { - if (this->name_.compare(0, 4, ".rel") == 0) - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && (this->output_section_->type() == elfcpp::SHT_REL - || this->output_section_->type() == elfcpp::SHT_RELA)) - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_PROGBITS - && (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0) - return true; - } - else if (os->type() == elfcpp::SHT_PROGBITS - && (os->flags() & elfcpp::SHF_WRITE) != 0) - { - if (this->name_ == ".data") - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_PROGBITS - && (this->output_section_->flags() & elfcpp::SHF_WRITE) != 0) - return true; - } - else if (os->type() == elfcpp::SHT_PROGBITS - && (os->flags() & elfcpp::SHF_EXECINSTR) != 0) - { - if (this->name_ == ".text") - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_PROGBITS - && (this->output_section_->flags() & elfcpp::SHF_EXECINSTR) != 0) - return true; - } - else if (os->type() == elfcpp::SHT_PROGBITS - || (os->type() != elfcpp::SHT_PROGBITS - && (os->flags() & elfcpp::SHF_WRITE) == 0)) - { - if (this->name_ == ".rodata") - { - *exact = true; - return true; - } - if (this->output_section_ != NULL - && this->output_section_->type() == elfcpp::SHT_PROGBITS - && (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0) - return true; - } - - return false; -} - // 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. @@ -2008,9 +2155,19 @@ class Orphan_output_section : public Sections_element : os_(os) { } - // Return whether to place an orphan section after this one. + // 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 - place_orphan_here(const Output_section *os, bool* exact, bool*) const; + 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 @@ -2038,23 +2195,6 @@ class Orphan_output_section : public Sections_element Output_section* os_; }; -// Whether to place another orphan section after this one. - -bool -Orphan_output_section::place_orphan_here(const Output_section* os, - bool* exact, - bool* is_relro) const -{ - if (this->os_->type() == os->type() - && this->os_->flags() == os->flags()) - { - *exact = true; - *is_relro = this->os_->is_relro(); - return true; - } - return false; -} - // Set section addresses. void @@ -2256,7 +2396,9 @@ Script_sections::Script_sections() sections_elements_(NULL), output_section_(NULL), phdrs_elements_(NULL), - data_segment_align_index_(-1U), + orphan_section_placement_(NULL), + data_segment_align_start_(), + saw_data_segment_align_(false), saw_relro_end_(false) { } @@ -2391,9 +2533,13 @@ Script_sections::add_input_section(const Input_section_spec* spec, bool keep) void Script_sections::data_segment_align() { - if (this->data_segment_align_index_ != -1U) + if (this->saw_data_segment_align_) gold_error(_("DATA_SEGMENT_ALIGN may only appear once in a linker script")); - this->data_segment_align_index_ = this->sections_elements_->size(); + 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 @@ -2407,14 +2553,13 @@ Script_sections::data_segment_relro_end() "in a linker script")); this->saw_relro_end_ = true; - if (this->data_segment_align_index_ == -1U) + if (!this->saw_data_segment_align_) gold_error(_("DATA_SEGMENT_RELRO_END must follow DATA_SEGMENT_ALIGN")); else { - for (size_t i = this->data_segment_align_index_; - i < this->sections_elements_->size(); - ++i) - (*this->sections_elements_)[i]->set_is_relro(); + Sections_elements::iterator p = this->data_segment_align_start_; + for (++p; p != this->sections_elements_->end(); ++p) + (*p)->set_is_relro(); } } @@ -2500,35 +2645,49 @@ Script_sections::output_section_name(const char* file_name, void Script_sections::place_orphan(Output_section* os) { - // Look for an output section definition which matches the output - // section. Put a marker after that section. - bool is_relro = false; - Sections_elements::iterator place = this->sections_elements_->end(); - for (Sections_elements::iterator p = this->sections_elements_->begin(); - p != this->sections_elements_->end(); - ++p) + Orphan_section_placement* osp = this->orphan_section_placement_; + if (osp == NULL) { - bool exact = false; - bool is_relro_here; - if ((*p)->place_orphan_here(os, &exact, &is_relro_here)) - { - place = p; - is_relro = is_relro_here; - if (exact) - break; - } + // 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; } - // The insert function puts the new element before the iterator. - if (place != this->sections_elements_->end()) - ++place; + Orphan_output_section* orphan = new Orphan_output_section(os); - this->sections_elements_->insert(place, 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(); - if (is_relro) - os->set_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(); + { + 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 diff --git a/gold/script-sections.h b/gold/script-sections.h index 465c24e..390c350 100644 --- a/gold/script-sections.h +++ b/gold/script-sections.h @@ -1,6 +1,6 @@ // script-sections.h -- linker script SECTIONS for gold -*- C++ -*- -// Copyright 2008 Free Software Foundation, Inc. +// Copyright 2008, 2009 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. @@ -26,6 +26,7 @@ #define GOLD_SCRIPT_SECTIONS_H #include <cstdio> +#include <list> #include <vector> namespace gold @@ -41,9 +42,15 @@ class Output_data; class Output_section_definition; class Output_section; class Output_segment; +class Orphan_section_placement; class Script_sections { + private: + // This is a list, not a vector, because we insert orphan sections + // in the middle. + typedef std::list<Sections_element*> Sections_elements; + public: Script_sections(); @@ -184,9 +191,10 @@ class Script_sections void print(FILE*) const; - private: - typedef std::vector<Sections_element*> Sections_elements; + // Used for orphan sections. + typedef Sections_elements::iterator Elements_iterator; + private: typedef std::vector<Phdrs_element*> Phdrs_elements; // Create segments. @@ -232,9 +240,13 @@ class Script_sections Output_section_definition* output_section_; // The list of program headers in the PHDRS clause. Phdrs_elements* phdrs_elements_; - // The index of the next Sections_element when we see + // Where to put orphan sections. + Orphan_section_placement* orphan_section_placement_; + // A pointer to the last Sections_element when we see // DATA_SEGMENT_ALIGN. - size_t data_segment_align_index_; + Sections_elements::iterator data_segment_align_start_; + // Whether we have seen DATA_SEGMENT_ALIGN. + bool saw_data_segment_align_; // Whether we have seen DATA_SEGMENT_RELRO_END. bool saw_relro_end_; }; |