#include "tls.h"
#include "freebsd.h"
#include "gc.h"
+#include "icf.h"
namespace
{
: Target_freebsd<64, false>(&x86_64_info),
got_(NULL), plt_(NULL), got_plt_(NULL), global_offset_table_(NULL),
rela_dyn_(NULL), copy_relocs_(elfcpp::R_X86_64_COPY), dynbss_(NULL),
- got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
+ got_mod_index_offset_(-1U), tlsdesc_reloc_info_(),
+ tls_base_symbol_defined_(false)
{ }
+ // This function should be defined in targets that can use relocation
+ // types to determine (implemented in local_reloc_may_be_function_pointer
+ // and global_reloc_may_be_function_pointer)
+ // if a function's pointer is taken. ICF uses this in safe mode to only
+ // fold those functions whose pointer is defintely not taken. For x86_64
+ // pie binaries, safe ICF cannot be done by looking at relocation types.
+ inline bool
+ can_check_for_function_pointers() const
+ { return !parameters->options().pie(); }
+
// Hook for a new output section.
void
do_new_output_section(Output_section*) const;
do_is_defined_by_abi(const Symbol* sym) const
{ return strcmp(sym->name(), "__tls_get_addr") == 0; }
+ // Return the symbol index to use for a target specific relocation.
+ // The only target specific relocation is R_X86_64_TLSDESC for a
+ // local symbol, which is an absolute reloc.
+ unsigned int
+ do_reloc_symbol_index(void*, unsigned int r_type) const
+ {
+ gold_assert(r_type == elfcpp::R_X86_64_TLSDESC);
+ return 0;
+ }
+
+ // Return the addend to use for a target specific relocation.
+ uint64_t
+ do_reloc_addend(void* arg, unsigned int r_type, uint64_t addend) const;
+
// Adjust -fstack-split code which calls non-stack-split code.
void
do_calls_non_split(Relobj* object, unsigned int shndx,
return this->got_->data_size();
}
+ // Add a new reloc argument, returning the index in the vector.
+ size_t
+ add_tlsdesc_info(Sized_relobj<64, false>* object, unsigned int r_sym)
+ {
+ this->tlsdesc_reloc_info_.push_back(Tlsdesc_info(object, r_sym));
+ return this->tlsdesc_reloc_info_.size() - 1;
+ }
+
private:
// The class which scans relocations.
class Scan
const elfcpp::Rela<64, false>& reloc, unsigned int r_type,
Symbol* gsym);
+ inline bool
+ local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
+ Target_x86_64* target,
+ Sized_relobj<64, false>* object,
+ unsigned int data_shndx,
+ Output_section* output_section,
+ const elfcpp::Rela<64, false>& reloc,
+ unsigned int r_type,
+ const elfcpp::Sym<64, false>& lsym);
+
+ inline bool
+ global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
+ Target_x86_64* target,
+ Sized_relobj<64, false>* object,
+ unsigned int data_shndx,
+ Output_section* output_section,
+ const elfcpp::Rela<64, false>& reloc,
+ unsigned int r_type,
+ Symbol* gsym);
+
private:
static void
unsupported_reloc_local(Sized_relobj<64, false>*, unsigned int r_type);
void
check_non_pic(Relobj*, unsigned int r_type);
+ inline bool
+ possible_function_pointer_reloc(unsigned int r_type);
+
// Whether we have issued an error about a non-PIC compilation.
bool issued_non_pic_error_;
};
Reloc_section*
rela_dyn_section(Layout*);
+ // Get the section to use for TLSDESC relocations.
+ Reloc_section*
+ rela_tlsdesc_section(Layout*) const;
+
// Add a potential copy relocation.
void
copy_reloc(Symbol_table* symtab, Layout* layout,
GOT_TYPE_TLS_DESC = 3 // GOT entry for TLS_DESC pair
};
+ // This type is used as the argument to the target specific
+ // relocation routines. The only target specific reloc is
+ // R_X86_64_TLSDESC against a local symbol.
+ struct Tlsdesc_info
+ {
+ Tlsdesc_info(Sized_relobj<64, false>* a_object, unsigned int a_r_sym)
+ : object(a_object), r_sym(a_r_sym)
+ { }
+
+ // The object in which the local symbol is defined.
+ Sized_relobj<64, false>* object;
+ // The local symbol index in the object.
+ unsigned int r_sym;
+ };
+
// The GOT section.
Output_data_got<64, false>* got_;
// The PLT section.
Output_data_space* dynbss_;
// Offset of the GOT entry for the TLS module index.
unsigned int got_mod_index_offset_;
+ // We handle R_X86_64_TLSDESC against a local symbol as a target
+ // specific relocation. Here we store the object and local symbol
+ // index for the relocation.
+ std::vector<Tlsdesc_info> tlsdesc_reloc_info_;
// True if the _TLS_MODULE_BASE_ symbol has been defined.
bool tls_base_symbol_defined_;
};
get_tlsdesc_plt_offset() const
{ return (this->count_ + 1) * plt_entry_size; }
- // Return the .rel.plt section data.
+ // Return the .rela.plt section data.
const Reloc_section*
- rel_plt() const
+ rela_plt() const
{ return this->rel_; }
+ // Return where the TLSDESC relocations should go.
+ Reloc_section*
+ rela_tlsdesc(Layout*);
+
protected:
void
do_adjust_output_section(Output_section* os);
// The reloc section.
Reloc_section* rel_;
+ // The TLSDESC relocs, if necessary. These must follow the regular
+ // PLT relocs.
+ Reloc_section* tlsdesc_rel_;
// The .got section.
Output_data_got<64, false>* got_;
// The .got.plt section.
Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
Output_data_got<64, false>* got,
Output_data_space* got_plt)
- : Output_section_data(8), got_(got), got_plt_(got_plt), count_(0),
- tlsdesc_got_offset_(-1U)
+ : Output_section_data(8), tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt),
+ count_(0), tlsdesc_got_offset_(-1U)
{
this->rel_ = new Reloc_section(false);
layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
// appear in the relocations.
}
+// Return where the TLSDESC relocations should go, creating it if
+// necessary. These follow the JUMP_SLOT relocations.
+
+Output_data_plt_x86_64::Reloc_section*
+Output_data_plt_x86_64::rela_tlsdesc(Layout* layout)
+{
+ if (this->tlsdesc_rel_ == NULL)
+ {
+ this->tlsdesc_rel_ = new Reloc_section(false);
+ layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
+ elfcpp::SHF_ALLOC, this->tlsdesc_rel_,
+ true, false, false, false);
+ gold_assert(this->tlsdesc_rel_->output_section() ==
+ this->rel_->output_section());
+ }
+ return this->tlsdesc_rel_;
+}
+
// Set the final size.
void
Output_data_plt_x86_64::set_final_data_size()
}
}
+// Return the section for TLSDESC relocations.
+
+Target_x86_64::Reloc_section*
+Target_x86_64::rela_tlsdesc_section(Layout* layout) const
+{
+ return this->plt_section()->rela_tlsdesc(layout);
+}
+
// Create a PLT entry for a global symbol.
void
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
- unsigned int shndx = lsym.get_st_shndx();
- bool is_ordinary;
- shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
- if (!is_ordinary)
- object->error(_("local symbol %u has bad shndx %u"),
- r_sym, shndx);
- else
- got->add_local_pair_with_rela(object, r_sym,
- shndx,
- GOT_TYPE_TLS_DESC,
- target->rela_dyn_section(layout),
- elfcpp::R_X86_64_TLSDESC, 0);
+ if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
+ {
+ unsigned int got_offset = got->add_constant(0);
+ got->add_constant(0);
+ object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
+ got_offset);
+ Reloc_section* rt = target->rela_tlsdesc_section(layout);
+ // We store the arguments we need in a vector, and
+ // use the index into the vector as the parameter
+ // to pass to the target specific routines.
+ uintptr_t intarg = target->add_tlsdesc_info(object, r_sym);
+ void* arg = reinterpret_cast<void*>(intarg);
+ rt->add_target_specific(elfcpp::R_X86_64_TLSDESC, arg,
+ got, got_offset, 0);
+ }
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
object->name().c_str(), r_type, gsym->demangled_name().c_str());
}
+// Returns true if this relocation type could be that of a function pointer.
+inline bool
+Target_x86_64::Scan::possible_function_pointer_reloc(unsigned int r_type)
+{
+ switch (r_type)
+ {
+ case elfcpp::R_X86_64_64:
+ case elfcpp::R_X86_64_32:
+ case elfcpp::R_X86_64_32S:
+ case elfcpp::R_X86_64_16:
+ case elfcpp::R_X86_64_8:
+ case elfcpp::R_X86_64_GOT64:
+ case elfcpp::R_X86_64_GOT32:
+ case elfcpp::R_X86_64_GOTPCREL64:
+ case elfcpp::R_X86_64_GOTPCREL:
+ case elfcpp::R_X86_64_GOTPLT64:
+ {
+ return true;
+ }
+ }
+ return false;
+}
+
+// For safe ICF, scan a relocation for a local symbol to check if it
+// corresponds to a function pointer being taken. In that case mark
+// the function whose pointer was taken as not foldable.
+
+inline bool
+Target_x86_64::Scan::local_reloc_may_be_function_pointer(
+ Symbol_table* ,
+ Layout* ,
+ Target_x86_64* ,
+ Sized_relobj<64, false>* ,
+ unsigned int ,
+ Output_section* ,
+ const elfcpp::Rela<64, false>& ,
+ unsigned int r_type,
+ const elfcpp::Sym<64, false>&)
+{
+ // When building a shared library, do not fold any local symbols as it is
+ // not possible to distinguish pointer taken versus a call by looking at
+ // the relocation types.
+ return (parameters->options().shared()
+ || possible_function_pointer_reloc(r_type));
+}
+
+// For safe ICF, scan a relocation for a global symbol to check if it
+// corresponds to a function pointer being taken. In that case mark
+// the function whose pointer was taken as not foldable.
+
+inline bool
+Target_x86_64::Scan::global_reloc_may_be_function_pointer(
+ Symbol_table*,
+ Layout* ,
+ Target_x86_64* ,
+ Sized_relobj<64, false>* ,
+ unsigned int ,
+ Output_section* ,
+ const elfcpp::Rela<64, false>& ,
+ unsigned int r_type,
+ Symbol* gsym)
+{
+ // When building a shared library, do not fold symbols whose visibility
+ // is hidden, internal or protected.
+ return ((parameters->options().shared()
+ && (gsym->visibility() == elfcpp::STV_INTERNAL
+ || gsym->visibility() == elfcpp::STV_PROTECTED
+ || gsym->visibility() == elfcpp::STV_HIDDEN))
+ || possible_function_pointer_reloc(r_type));
+}
+
// Scan a relocation for a global symbol.
inline void
// Create a double GOT entry with an R_X86_64_TLSDESC reloc.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
- got->add_global_pair_with_rela(gsym, GOT_TYPE_TLS_DESC,
- target->rela_dyn_section(layout),
+ Reloc_section *rt = target->rela_tlsdesc_section(layout);
+ got->add_global_pair_with_rela(gsym, GOT_TYPE_TLS_DESC, rt,
elfcpp::R_X86_64_TLSDESC, 0);
}
else if (optimized_type == tls::TLSOPT_TO_IE)
const Input_objects*,
Symbol_table* symtab)
{
+ const Reloc_section* rel_plt = (this->plt_ == NULL
+ ? NULL
+ : this->plt_->rela_plt());
+ layout->add_target_dynamic_tags(false, this->got_plt_, rel_plt,
+ this->rela_dyn_, true, false);
+
// Fill in some more dynamic tags.
Output_data_dynamic* const odyn = layout->dynamic_data();
if (odyn != NULL)
{
- if (this->got_plt_ != NULL
- && this->got_plt_->output_section() != NULL)
- odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
-
if (this->plt_ != NULL
- && this->plt_->output_section() != NULL)
- {
- const Output_data* od = this->plt_->rel_plt();
- odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
- odyn->add_section_address(elfcpp::DT_JMPREL, od);
- odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_RELA);
- if (this->plt_->has_tlsdesc_entry())
- {
- unsigned int plt_offset = this->plt_->get_tlsdesc_plt_offset();
- unsigned int got_offset = this->plt_->get_tlsdesc_got_offset();
- this->got_->finalize_data_size();
- odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_PLT,
- this->plt_, plt_offset);
- odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_GOT,
- this->got_, got_offset);
- }
- }
-
- if (this->rela_dyn_ != NULL
- && this->rela_dyn_->output_section() != NULL)
- {
- const Output_data* od = this->rela_dyn_;
- odyn->add_section_address(elfcpp::DT_RELA, od);
- odyn->add_section_size(elfcpp::DT_RELASZ, od);
- odyn->add_constant(elfcpp::DT_RELAENT,
- elfcpp::Elf_sizes<64>::rela_size);
- }
-
- if (!parameters->options().shared())
+ && this->plt_->output_section() != NULL
+ && this->plt_->has_tlsdesc_entry())
{
- // The value of the DT_DEBUG tag is filled in by the dynamic
- // linker at run time, and used by the debugger.
- odyn->add_constant(elfcpp::DT_DEBUG, 0);
+ unsigned int plt_offset = this->plt_->get_tlsdesc_plt_offset();
+ unsigned int got_offset = this->plt_->get_tlsdesc_got_offset();
+ this->got_->finalize_data_size();
+ odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_PLT,
+ this->plt_, plt_offset);
+ odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_GOT,
+ this->got_, got_offset);
}
}
elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
const bool is_final = (gsym == NULL
- ? !parameters->options().output_is_position_independent()
+ ? !parameters->options().shared()
: gsym->final_value_is_known());
const tls::Tls_optimization optimized_type
= Target_x86_64::optimize_tls_reloc(is_final, r_type);
return std::string(nops[length], length);
}
+// Return the addend to use for a target specific relocation. The
+// only target specific relocation is R_X86_64_TLSDESC for a local
+// symbol. We want to set the addend is the offset of the local
+// symbol in the TLS segment.
+
+uint64_t
+Target_x86_64::do_reloc_addend(void* arg, unsigned int r_type,
+ uint64_t) const
+{
+ gold_assert(r_type == elfcpp::R_X86_64_TLSDESC);
+ uintptr_t intarg = reinterpret_cast<uintptr_t>(arg);
+ gold_assert(intarg < this->tlsdesc_reloc_info_.size());
+ const Tlsdesc_info& ti(this->tlsdesc_reloc_info_[intarg]);
+ const Symbol_value<64>* psymval = ti.object->local_symbol(ti.r_sym);
+ gold_assert(psymval->is_tls_symbol());
+ // The value of a TLS symbol is the offset in the TLS segment.
+ return psymval->value(ti.object, 0);
+}
+
// FNOFFSET in section SHNDX in OBJECT is the start of a function
// compiled with -fstack-split. The function calls non-stack-split
// code. We have to change the function so that it always ensures
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