diff options
Diffstat (limited to 'gold/arm.cc')
| -rw-r--r-- | gold/arm.cc | 280 |
1 files changed, 214 insertions, 66 deletions
diff --git a/gold/arm.cc b/gold/arm.cc index d104033..b77adc7 100644 --- a/gold/arm.cc +++ b/gold/arm.cc @@ -137,22 +137,27 @@ class Insn_template enum Type { THUMB16_TYPE = 1, + // THUMB16_SPECIAL_TYPE is used by sub-classes of Stub for instruction + // templates with class-specific semantics. Currently this is used + // only by the Cortex_a8_stub class for handling condition codes in + // conditional branches. + THUMB16_SPECIAL_TYPE, THUMB32_TYPE, ARM_TYPE, DATA_TYPE }; - // Factory methods to create instrunction templates in different formats. + // Factory methods to create instruction templates in different formats. static const Insn_template thumb16_insn(uint32_t data) { return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 0); } - // A bit of a hack. A Thumb conditional branch, in which the proper - // condition is inserted when we build the stub. + // A Thumb conditional branch, in which the proper condition is inserted + // when we build the stub. static const Insn_template thumb16_bcond_insn(uint32_t data) - { return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 1); } + { return Insn_template(data, THUMB16_SPECIAL_TYPE, elfcpp::R_ARM_NONE, 1); } static const Insn_template thumb32_insn(uint32_t data) @@ -198,11 +203,11 @@ class Insn_template reloc_addend() const { return this->reloc_addend_; } - // Return size of instrunction template in bytes. + // Return size of instruction template in bytes. size_t size() const; - // Return byte-alignment of instrunction template. + // Return byte-alignment of instruction template. unsigned alignment() const; @@ -410,16 +415,39 @@ class Stub write(unsigned char* view, section_size_type view_size, bool big_endian) { this->do_write(view, view_size, big_endian); } + // Return the instruction for THUMB16_SPECIAL_TYPE instruction template + // for the i-th instruction. + uint16_t + thumb16_special(size_t i) + { return this->do_thumb16_special(i); } + protected: // This must be defined in the child class. virtual Arm_address do_reloc_target(size_t) = 0; - // This must be defined in the child class. + // This may be overridden in the child class. virtual void - do_write(unsigned char*, section_size_type, bool) = 0; + do_write(unsigned char* view, section_size_type view_size, bool big_endian) + { + if (big_endian) + this->do_fixed_endian_write<true>(view, view_size); + else + this->do_fixed_endian_write<false>(view, view_size); + } + // This must be overridden if a child class uses the THUMB16_SPECIAL_TYPE + // instruction template. + virtual uint16_t + do_thumb16_special(size_t) + { gold_unreachable(); } + private: + // A template to implement do_write. + template<bool big_endian> + void inline + do_fixed_endian_write(unsigned char*, section_size_type); + // Its template. const Stub_template* stub_template_; // Offset within the section of containing this stub. @@ -594,7 +622,6 @@ class Reloc_stub : public Stub friend class Stub_factory; - private: // Return the relocation target address of the i-th relocation in the // stub. Arm_address @@ -605,17 +632,115 @@ class Reloc_stub : public Stub return this->destination_address_; } - // A template to implement do_write below. - template<bool big_endian> - void inline - do_fixed_endian_write(unsigned char*, section_size_type); + private: + // Address of destination. + Arm_address destination_address_; +}; - // Write a stub. - void - do_write(unsigned char* view, section_size_type view_size, bool big_endian); +// Cortex-A8 stub class. We need a Cortex-A8 stub to redirect any 32-bit +// THUMB branch that meets the following conditions: +// +// 1. The branch straddles across a page boundary. i.e. lower 12-bit of +// branch address is 0xffe. +// 2. The branch target address is in the same page as the first word of the +// branch. +// 3. The branch follows a 32-bit instruction which is not a branch. +// +// To do the fix up, we need to store the address of the branch instruction +// and its target at least. We also need to store the original branch +// instruction bits for the condition code in a conditional branch. The +// condition code is used in a special instruction template. We also want +// to identify input sections needing Cortex-A8 workaround quickly. We store +// extra information about object and section index of the code section +// containing a branch being fixed up. The information is used to mark +// the code section when we finalize the Cortex-A8 stubs. +// - // Address of destination. +class Cortex_a8_stub : public Stub +{ + public: + ~Cortex_a8_stub() + { } + + // Return the object of the code section containing the branch being fixed + // up. + Relobj* + relobj() const + { return this->relobj_; } + + // Return the section index of the code section containing the branch being + // fixed up. + unsigned int + shndx() const + { return this->shndx_; } + + // Return the source address of stub. This is the address of the original + // branch instruction. LSB is 1 always set to indicate that it is a THUMB + // instruction. + Arm_address + source_address() const + { return this->source_address_; } + + // Return the destination address of the stub. This is the branch taken + // address of the original branch instruction. LSB is 1 if it is a THUMB + // instruction address. + Arm_address + destination_address() const + { return this->destination_address_; } + + // Return the instruction being fixed up. + uint32_t + original_insn() const + { return this->original_insn_; } + + protected: + // Cortex_a8_stubs are created via a stub factory. So these are protected. + Cortex_a8_stub(const Stub_template* stub_template, Relobj* relobj, + unsigned int shndx, Arm_address source_address, + Arm_address destination_address, uint32_t original_insn) + : Stub(stub_template), relobj_(relobj), shndx_(shndx), + source_address_(source_address | 1U), + destination_address_(destination_address), + original_insn_(original_insn) + { } + + friend class Stub_factory; + + // Return the relocation target address of the i-th relocation in the + // stub. + Arm_address + do_reloc_target(size_t i) + { + if (this->stub_template()->type() == arm_stub_a8_veneer_b_cond) + { + // The conditional branch veneer has two relocations. + gold_assert(i < 2); + return i == 0 ? this->source_address_ + 4 : this->destination_address_; + } + else + { + // All other Cortex-A8 stubs have only one relocation. + gold_assert(i == 0); + return this->destination_address_; + } + } + + // Return an instruction for the THUMB16_SPECIAL_TYPE instruction template. + uint16_t + do_thumb16_special(size_t); + + private: + // Object of the code section containing the branch being fixed up. + Relobj* relobj_; + // Section index of the code section containing the branch begin fixed up. + unsigned int shndx_; + // Source address of original branch. + Arm_address source_address_; + // Destination address of the original branch. Arm_address destination_address_; + // Original branch instruction. This is needed for copying the condition + // code from a condition branch to its stub. + uint32_t original_insn_; }; // Stub factory class. @@ -640,6 +765,18 @@ class Stub_factory return new Reloc_stub(this->stub_templates_[stub_type]); } + // Make a Cortex-A8 stub. + Cortex_a8_stub* + make_cortex_a8_stub(Stub_type stub_type, Relobj* relobj, unsigned int shndx, + Arm_address source, Arm_address destination, + uint32_t original_insn) const + { + gold_assert(stub_type >= arm_stub_cortex_a8_first + && stub_type <= arm_stub_cortex_a8_last); + return new Cortex_a8_stub(this->stub_templates_[stub_type], relobj, shndx, + source, destination, original_insn); + } + private: // Constructor and destructor are protected since we only return a single // instance created in Stub_factory::get_instance(). @@ -2728,6 +2865,51 @@ Stub_template::Stub_template( this->size_ = offset; } +// Stub methods. + +// Template to implement do_write for a specific target endianity. + +template<bool big_endian> +void inline +Stub::do_fixed_endian_write(unsigned char* view, section_size_type view_size) +{ + const Stub_template* stub_template = this->stub_template(); + const Insn_template* insns = stub_template->insns(); + + // FIXME: We do not handle BE8 encoding yet. + unsigned char* pov = view; + for (size_t i = 0; i < stub_template->insn_count(); i++) + { + switch (insns[i].type()) + { + case Insn_template::THUMB16_TYPE: + elfcpp::Swap<16, big_endian>::writeval(pov, insns[i].data() & 0xffff); + break; + case Insn_template::THUMB16_SPECIAL_TYPE: + elfcpp::Swap<16, big_endian>::writeval( + pov, + this->thumb16_special(i)); + break; + case Insn_template::THUMB32_TYPE: + { + uint32_t hi = (insns[i].data() >> 16) & 0xffff; + uint32_t lo = insns[i].data() & 0xffff; + elfcpp::Swap<16, big_endian>::writeval(pov, hi); + elfcpp::Swap<16, big_endian>::writeval(pov + 2, lo); + } + break; + case Insn_template::ARM_TYPE: + case Insn_template::DATA_TYPE: + elfcpp::Swap<32, big_endian>::writeval(pov, insns[i].data()); + break; + default: + gold_unreachable(); + } + pov += insns[i].size(); + } + gold_assert(static_cast<section_size_type>(pov - view) == view_size); +} + // Reloc_stub::Key methods. // Dump a Key as a string for debugging. @@ -2934,57 +3116,23 @@ Reloc_stub::stub_type_for_reloc( return stub_type; } -// Template to implement do_write for a specific target endianity. - -template<bool big_endian> -void inline -Reloc_stub::do_fixed_endian_write(unsigned char* view, - section_size_type view_size) -{ - const Stub_template* stub_template = this->stub_template(); - const Insn_template* insns = stub_template->insns(); - - // FIXME: We do not handle BE8 encoding yet. - unsigned char* pov = view; - for (size_t i = 0; i < stub_template->insn_count(); i++) - { - switch (insns[i].type()) - { - case Insn_template::THUMB16_TYPE: - // Non-zero reloc addends are only used in Cortex-A8 stubs. - gold_assert(insns[i].reloc_addend() == 0); - elfcpp::Swap<16, big_endian>::writeval(pov, insns[i].data() & 0xffff); - break; - case Insn_template::THUMB32_TYPE: - { - uint32_t hi = (insns[i].data() >> 16) & 0xffff; - uint32_t lo = insns[i].data() & 0xffff; - elfcpp::Swap<16, big_endian>::writeval(pov, hi); - elfcpp::Swap<16, big_endian>::writeval(pov + 2, lo); - } - break; - case Insn_template::ARM_TYPE: - case Insn_template::DATA_TYPE: - elfcpp::Swap<32, big_endian>::writeval(pov, insns[i].data()); - break; - default: - gold_unreachable(); - } - pov += insns[i].size(); - } - gold_assert(static_cast<section_size_type>(pov - view) == view_size); -} +// Cortex_a8_stub methods. -// Write a reloc stub to VIEW with endianity specified by BIG_ENDIAN. +// Return the instruction for a THUMB16_SPECIAL_TYPE instruction template. +// I is the position of the instruction template in the stub template. -void -Reloc_stub::do_write(unsigned char* view, section_size_type view_size, - bool big_endian) +uint16_t +Cortex_a8_stub::do_thumb16_special(size_t i) { - if (big_endian) - this->do_fixed_endian_write<true>(view, view_size); - else - this->do_fixed_endian_write<false>(view, view_size); + // The only use of this is to copy condition code from a conditional + // branch being worked around to the corresponding conditional branch in + // to the stub. + gold_assert(this->stub_template()->type() == arm_stub_a8_veneer_b_cond + && i == 0); + uint16_t data = this->stub_template()->insns()[i].data(); + gold_assert((data & 0xff00U) == 0xd000U); + data |= ((this->original_insn_ >> 22) & 0xf) << 8; + return data; } // Stub_factory methods. @@ -3162,7 +3310,7 @@ Stub_factory::Stub_factory() // Stub used for Thumb-2 blx.w instructions. We modified the original blx.w // instruction (which switches to ARM mode) to point to this stub. Jump to // the real destination using an ARM-mode branch. - const Insn_template elf32_arm_stub_a8_veneer_blx[] = + static const Insn_template elf32_arm_stub_a8_veneer_blx[] = { Insn_template::arm_rel_insn(0xea000000, -8) // b dest }; |