2010-06-25 Doug Kwan <dougkwan@google.com>
* arm.cc (Target_arm::can_check_for_functions_pointers): Return true. (Target_arm::section_may_have_icf_unsafe_pointers): New method definition. (Target_arm::Scan::local_reloc_may_be_function_pointer, Target_arm::Scan::global_reloc_may_be_function_pointer): Implement target hook to detect function points. (Target_arm::Scan::possible_function_pointer_reloc): New method. * icf.h (Icf::check_section_for_function_pointers): Change type of parameter SECTION_NAME to const reference to std::string. Use target hook to determine if section may have unsafe pointers. * target.h (Target::section_may_have_icf_unsafe_pointers): New method definition.
This commit is contained in:
Doug Kwan
parent
4f2a93bda2
commit
8a75a161b2
4 changed files with 120 additions and 8 deletions
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@ -1,3 +1,18 @@
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2010-06-25 Doug Kwan <dougkwan@google.com>
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* arm.cc (Target_arm::can_check_for_functions_pointers): Return true.
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(Target_arm::section_may_have_icf_unsafe_pointers): New method
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definition.
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(Target_arm::Scan::local_reloc_may_be_function_pointer,
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Target_arm::Scan::global_reloc_may_be_function_pointer): Implement
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target hook to detect function points.
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(Target_arm::Scan::possible_function_pointer_reloc): New method.
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* icf.h (Icf::check_section_for_function_pointers): Change type of
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parameter SECTION_NAME to const reference to std::string. Use
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target hook to determine if section may have unsafe pointers.
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* target.h (Target::section_may_have_icf_unsafe_pointers): New
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method definition.
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2010-06-21 Rafael Espindola <espindola@google.com>
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* fileread.cc (Input_file::find_fie): New
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92
gold/arm.cc
92
gold/arm.cc
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@ -2109,6 +2109,23 @@ class Target_arm : public Sized_target<32, big_endian>
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fix_cortex_a8_(false), cortex_a8_relocs_info_()
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{ }
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// Virtual function which is set to return true by a target if
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// it can use relocation types to determine if a function's
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// pointer is taken.
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virtual bool
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can_check_for_function_pointers() const
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{ return true; }
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// Whether a section called SECTION_NAME may have function pointers to
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// sections not eligible for safe ICF folding.
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virtual bool
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section_may_have_icf_unsafe_pointers(const char* section_name) const
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{
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return (!is_prefix_of(".ARM.exidx", section_name)
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&& !is_prefix_of(".ARM.extab", section_name)
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&& Target::section_may_have_icf_unsafe_pointers(section_name));
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}
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// Whether we can use BLX.
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bool
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may_use_blx() const
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@ -2474,8 +2491,7 @@ class Target_arm : public Sized_target<32, big_endian>
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Output_section* ,
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const elfcpp::Rel<32, big_endian>& ,
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unsigned int ,
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const elfcpp::Sym<32, big_endian>&)
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{ return false; }
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const elfcpp::Sym<32, big_endian>&);
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inline bool
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global_reloc_may_be_function_pointer(Symbol_table* , Layout* , Target_arm* ,
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@ -2483,8 +2499,7 @@ class Target_arm : public Sized_target<32, big_endian>
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unsigned int ,
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Output_section* ,
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const elfcpp::Rel<32, big_endian>& ,
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unsigned int , Symbol*)
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{ return false; }
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unsigned int , Symbol*);
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private:
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static void
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@ -2515,6 +2530,9 @@ class Target_arm : public Sized_target<32, big_endian>
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|| sym->is_preemptible()));
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}
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inline bool
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possible_function_pointer_reloc(unsigned int r_type);
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// Whether we have issued an error about a non-PIC compilation.
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bool issued_non_pic_error_;
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};
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@ -7688,6 +7706,72 @@ Target_arm<big_endian>::Scan::unsupported_reloc_global(
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object->name().c_str(), r_type, gsym->demangled_name().c_str());
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}
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template<bool big_endian>
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inline bool
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Target_arm<big_endian>::Scan::possible_function_pointer_reloc(
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unsigned int r_type)
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{
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switch (r_type)
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{
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case elfcpp::R_ARM_PC24:
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case elfcpp::R_ARM_THM_CALL:
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case elfcpp::R_ARM_PLT32:
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case elfcpp::R_ARM_CALL:
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case elfcpp::R_ARM_JUMP24:
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case elfcpp::R_ARM_THM_JUMP24:
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case elfcpp::R_ARM_SBREL31:
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case elfcpp::R_ARM_PREL31:
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case elfcpp::R_ARM_THM_JUMP19:
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case elfcpp::R_ARM_THM_JUMP6:
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case elfcpp::R_ARM_THM_JUMP11:
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case elfcpp::R_ARM_THM_JUMP8:
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// All the relocations above are branches except SBREL31 and PREL31.
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return false;
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default:
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// Be conservative and assume this is a function pointer.
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return true;
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}
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}
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template<bool big_endian>
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inline bool
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Target_arm<big_endian>::Scan::local_reloc_may_be_function_pointer(
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Symbol_table*,
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Layout*,
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Target_arm<big_endian>* target,
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Sized_relobj<32, big_endian>*,
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unsigned int,
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Output_section*,
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const elfcpp::Rel<32, big_endian>&,
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unsigned int r_type,
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const elfcpp::Sym<32, big_endian>&)
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{
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r_type = target->get_real_reloc_type(r_type);
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return possible_function_pointer_reloc(r_type);
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}
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template<bool big_endian>
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inline bool
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Target_arm<big_endian>::Scan::global_reloc_may_be_function_pointer(
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Symbol_table*,
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Layout*,
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Target_arm<big_endian>* target,
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Sized_relobj<32, big_endian>*,
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unsigned int,
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Output_section*,
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const elfcpp::Rel<32, big_endian>&,
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unsigned int r_type,
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Symbol* gsym)
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{
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// GOT is not a function.
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if (strcmp(gsym->name(), "_GLOBAL_OFFSET_TABLE_") == 0)
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return false;
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r_type = target->get_real_reloc_type(r_type);
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return possible_function_pointer_reloc(r_type);
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}
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// Scan a relocation for a global symbol.
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template<bool big_endian>
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@ -121,14 +121,13 @@ class Icf
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// corresponding to taken function pointers. Ignores eh_frame
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// and vtable sections.
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inline bool
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check_section_for_function_pointers(std::string section_name,
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check_section_for_function_pointers(const std::string& section_name,
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Target* target)
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{
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return (parameters->options().icf_safe_folding()
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&& target->can_check_for_function_pointers()
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&& !is_prefix_of(".rodata._ZTV", section_name.c_str())
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&& !is_prefix_of(".data.rel.ro._ZTV", section_name.c_str())
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&& !is_prefix_of(".eh_frame", section_name.c_str()));
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&& target->section_may_have_icf_unsafe_pointers(
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section_name.c_str()));
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}
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// Returns a map of a section to info (Reloc_info) about its relocations.
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@ -71,6 +71,20 @@ class Target
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can_check_for_function_pointers() const
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{ return false; }
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// Whether a section called SECTION_NAME may have function pointers to
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// sections not eligible for safe ICF folding.
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virtual bool
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section_may_have_icf_unsafe_pointers(const char* section_name) const
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{
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// We recognize sections for normal vtables, construction vtables and
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// EH frames.
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return (!is_prefix_of(".rodata._ZTV", section_name)
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&& !is_prefix_of(".data.rel.ro._ZTV", section_name)
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&& !is_prefix_of(".rodata._ZTC", section_name)
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&& !is_prefix_of(".data.rel.ro._ZTC", section_name)
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&& !is_prefix_of(".eh_frame", section_name));
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}
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// Return the bit size that this target implements. This should
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// return 32 or 64.
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int
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