arch/mips_tls

MIPS architecture-specific rules for TLS symbolization

TLS Models

1. Global Dynamic (GD) Model

The most general and flexible TLS model, which can access any thread-local variable defined in any shared library, even when the variable’s location is not known until runtime. This model performs a function call to __tls_get_addr through the GOT and TP offsets.

E.g.,

lw $v0, %got(__tls_get_addr)($gp) addiu $a0,$gp,%tlsgd(tls_var) move $t9,$v0 jalr $t9 nop

=> $v0 gets the address of tls_var.

2. Local Dynamic (LD) Model

Similar to Global Dynamic, but optimized when multiple TLS variables are known to be defined in the same module. The first access still calls __tls_get_addr, but subsequent accesses can reuse the base address, avoiding repeated calls.

E.g.:

lw $v0,%got(__tls_get_addr)($gp) addiu $a0, $gp, %tlsldm(TLS_BASE) move $t9,$v0 jalr $t9 nop move reg1,$v0 lui reg2,%dtprel_hi(tls_var) addu reg3,reg2,reg1

lw/sw reg4,%dtprel_lo(tls_var)(reg3)

=> reg4 gets the contents of tls_var. or

addiu reg4,reg3,%dtprel_lo(tls_var)

=> reg4 gets the address of tls_var.

3. Initial Exec (IE) Model

This model assumes that the TLS variable is part of the main executable or of a shared object that was included in the initial program image. It uses the GOT to access the variable relative to the thread pointer, without calling __tls_get_addr().

E.g.:

lw $v1,%gottprel(tls_var)($gp) addiu $v0,$v1,$tp

or

rdhwr $v1,$29 move $v0,$v1 lw $v1,%gottprel(i)($gp) addu $v0,$v1,$v0

4. Local Exec (LE) Model

The fastest, but least flexible: This model assumes that the TLS variable is defined in the same module (usually the main executable) and that its offset from the thread pointer is known at link time. No GOT access or function call is needed.

E.g.,

rdhwr reg1,$29 <- rdhwr (read hardware register), reg 29: thread pointer (TP) move regtemp, reg1 lui reg2, %tprel_hi(tls_var) addu reg3,reg2,regtemp

lw reg4, %tprel_lo(tls_var)(reg3)

=> reg4 gets the contents of tls_var. or

addiu reg4, reg3, %tprel_lo(tls_var)

add_reg_gp(AddEA:address, Reg:register, Dest:address)

A register gets GP-relative address. E.g., 0x04: addiu $v0, $gp, N => add_reg_gp(0x04,V0,GP_VALUE+N)

• Uses: arch.reg_arithmetic_operation, symbol

• Used by: tls_get_addr, tls_relative_operand, tls_relative_operand_mips

reg_flow(SrcEA:address, Reg:register, DestEA:address, RegTemp:register)

Register data flow in limited step

WARNING: Predicate not present in compiled Datalog program (Dead Code)

call_tls_get_addr_mips(Call:address, Reg:register)

E.g., 0x04: lw $v0, %got(__tls_get_addr)($gp) 0x08: addiu $a0, $gp, N 0x0C: jalr $v0 or 0x04: lw $v0, %got(__tls_get_addr)($gp) 0x08: addiu $a0, $gp, N 0x0C: move $t0,$v0 0x10: jalr $t0 => call_tls_get_addr(0x10,A0)

• Uses: arch.move_reg_reg, binary_format, got_reference_mips_global, reg_call

• Recursive: arm_jump_table_cmp_limit, value_reg_unsupported, value_reg, candidate_block_is_not_padding, gp_relative_operand, split_load_total_points, stack_def_use.def_used, indexed_pc_relative_load, branch_to_calculated_pc_rel_addr, code_in_block, jump_table_element_access, compare_and_jump_register, jump_table_candidate, invalid, block_candidate_boundaries, data_in_code_propagate, relocation_adjustment_total, arch.simple_data_load, local_dynamic_tls_candidate, block_limit, block_instruction_next, reg_def_use.used, wis_memo, stack_def_use.live_var_used_in_block, wis_has_prior, arm_jump_table_skip_first_entry, wis_schedule, flags_and_jump_pair, litpool_symbolic_operand, segment_target_range, inferred_main_in_reg, code_in_block_candidate_refined, unresolved_interval, code_in_block_candidate, reg_def_use.return_val_used, start_function, correlated_live_reg, indexed_pc_relative_load_relative, arm_jump_table_block_start, arch.reg_relative_load, arm_jump_table_data_block, next_block_in_byte_interval, impossible_block, reg_def_use.ambiguous_last_def_in_block, reg_def_use.live_var_at_prior_used, data_block_candidate, invalid_jump_table_candidate, compare_and_jump_indirect, reg_def_use.flow_def, arm_jump_table_data_block_limit, stack_base_reg_move, __agg_single3, base_relative_jump, arm_jump_table_block_instruction, __agg_subclause2, no_value_reg_limit, overlap_with_litpool, split_load_candidate, __agg_subclause4, padding_block_candidate, inferred_main_dispatch, relocation_adjustment, tls_get_addr, after_end, stack_def_use.defined_in_block, reg_def_use.used_in_block, stack_def_use.last_def_in_block, candidate_block_is_padding, plt_entry, jump_table_max, reg_def_use.live_var_at_block_end, initialized_data_segment, tls_relative_operand_mips, relative_address, litpool_ref, arm_jump_table_candidate_start, must_fallthrough, may_fallthrough, contains_implausible_instr_seq, __agg_subclause6, no_return_call_refined, block_points_proportional, no_return_block, cinf_ldr_add_pc, relative_address_start, adjusts_stack_in_block, resolved_reaches, block_total_points, next_end, possible_target_from, block_candidate_dependency_edge, block, self_contained_segment, block_next, reg_def_use.live_var_def, jump_table_signed, reg_has_got, no_return_call_propagated, wis_prior, split_load_conflict, jump_table_start, wis_schedule_iter, reg_def_use.ambiguous_block_last_def, jump_table_prelude, first_block_in_byte_interval, arch.extend_load, base_relative_operation, indefinite_litpool_ref, compare_and_jump_immediate, unresolved_block_overlap, split_load, stack_def_use.used_in_block, reg_reg_arithmetic_operation_defs, padding_block_limit, reg_def_use.def_used, tls_desc_call, litpool_boundaries, discarded_block, stack_def_use.live_var_def, base_relative_operand, data_in_code, plt_block, reg_used_for, overlapping_instruction, reg_has_base_image, cmp_defines, nop_in_padding_candidate, compare_and_jump_indirect_op_valid, data_block_limit, __agg_subclause7, block_implies_block, const_value_reg_used, reg_def_use.return_block_end, next_type, __agg_single10, adrp_used, symbol_minus_symbol_litpool_access_pattern, contains_plausible_instr_seq, got_relative_operand, jump_table_candidate_refined, stack_def_use.live_var_at_prior_used, possible_target, instruction_memory_access_size, block_points, basic_target, split_load_operand, incomplete_block, transition_block_limit, data_access, litpool_confidence, block_overlap, arm_jump_table_candidate, reg_def_use.block_last_def, reg_def_use.last_def_in_block, is_padding, simple_data_access_pattern, reg_def_use.live_var_used, straight_line_last_def, __agg_single2, inter_procedural_edge, init_symbol_minus_symbol_candidate_arm, function_inference.function_entry_initial, block_heuristic, hi_load_prop, unresolved_interval_order, symbolic_expr_from_relocation, discarded_split_load, likely_fallthrough, block_boundaries, call_tls_get_addr_mips, stack_def_use.block_last_def, __agg_single6, stack_def_use.live_var_at_block_end, split_load_point, cmp_reg_to_reg, unlikely_have_symbolic_immediate, reg_def_use.defined_in_block, jump_table_target, no_return_call, split_load_for_symbolization, call_tls_get_addr, __agg_subclause3, next_start, stack_def_use.ref_in_block, straight_line_def_used, def_used_for_address, init_ldr_add_pc, last_value_reg_limit, value_reg_edge, data_segment, common_tail, reg_def_use.ref_in_block, known_block, negative_block_heuristic, relative_jump_table_entry_candidate, stack_def_use.live_var_used, unresolved_block, block_last_instruction, value_reg_limit, composite_data_access

tls_relative_operand_mips(EA:address, Index:operand_index, Dest:address, Type:symbol, GotEntry:address, Sym:symbol)

A wrapper of tls_relative_operand with additional info including GOT entry and symbol name

• Uses: add_reg_gp, arch.reg_arithmetic_operation, defined_symbol, instruction_immediate_offset, relocation, tls_index, tls_segment

• Used by: inferred_symbol_mips, symbolic_operand_candidate

• Recursive: arm_jump_table_cmp_limit, value_reg_unsupported, value_reg, candidate_block_is_not_padding, gp_relative_operand, split_load_total_points, stack_def_use.def_used, indexed_pc_relative_load, branch_to_calculated_pc_rel_addr, code_in_block, jump_table_element_access, compare_and_jump_register, jump_table_candidate, invalid, block_candidate_boundaries, data_in_code_propagate, relocation_adjustment_total, arch.simple_data_load, local_dynamic_tls_candidate, block_limit, block_instruction_next, reg_def_use.used, wis_memo, stack_def_use.live_var_used_in_block, wis_has_prior, arm_jump_table_skip_first_entry, wis_schedule, flags_and_jump_pair, litpool_symbolic_operand, segment_target_range, inferred_main_in_reg, code_in_block_candidate_refined, unresolved_interval, code_in_block_candidate, reg_def_use.return_val_used, start_function, correlated_live_reg, indexed_pc_relative_load_relative, arm_jump_table_block_start, arch.reg_relative_load, arm_jump_table_data_block, next_block_in_byte_interval, impossible_block, reg_def_use.ambiguous_last_def_in_block, reg_def_use.live_var_at_prior_used, data_block_candidate, invalid_jump_table_candidate, compare_and_jump_indirect, reg_def_use.flow_def, arm_jump_table_data_block_limit, stack_base_reg_move, __agg_single3, base_relative_jump, arm_jump_table_block_instruction, __agg_subclause2, no_value_reg_limit, overlap_with_litpool, split_load_candidate, __agg_subclause4, padding_block_candidate, inferred_main_dispatch, relocation_adjustment, tls_get_addr, after_end, stack_def_use.defined_in_block, reg_def_use.used_in_block, stack_def_use.last_def_in_block, candidate_block_is_padding, plt_entry, jump_table_max, reg_def_use.live_var_at_block_end, initialized_data_segment, tls_relative_operand_mips, relative_address, litpool_ref, arm_jump_table_candidate_start, must_fallthrough, may_fallthrough, contains_implausible_instr_seq, __agg_subclause6, no_return_call_refined, block_points_proportional, no_return_block, cinf_ldr_add_pc, relative_address_start, adjusts_stack_in_block, resolved_reaches, block_total_points, next_end, possible_target_from, block_candidate_dependency_edge, block, self_contained_segment, block_next, reg_def_use.live_var_def, jump_table_signed, reg_has_got, no_return_call_propagated, wis_prior, split_load_conflict, jump_table_start, wis_schedule_iter, reg_def_use.ambiguous_block_last_def, jump_table_prelude, first_block_in_byte_interval, arch.extend_load, base_relative_operation, indefinite_litpool_ref, compare_and_jump_immediate, unresolved_block_overlap, split_load, stack_def_use.used_in_block, reg_reg_arithmetic_operation_defs, padding_block_limit, reg_def_use.def_used, tls_desc_call, litpool_boundaries, discarded_block, stack_def_use.live_var_def, base_relative_operand, data_in_code, plt_block, reg_used_for, overlapping_instruction, reg_has_base_image, cmp_defines, nop_in_padding_candidate, compare_and_jump_indirect_op_valid, data_block_limit, __agg_subclause7, block_implies_block, const_value_reg_used, reg_def_use.return_block_end, next_type, __agg_single10, adrp_used, symbol_minus_symbol_litpool_access_pattern, contains_plausible_instr_seq, got_relative_operand, jump_table_candidate_refined, stack_def_use.live_var_at_prior_used, possible_target, instruction_memory_access_size, block_points, basic_target, split_load_operand, incomplete_block, transition_block_limit, data_access, litpool_confidence, block_overlap, arm_jump_table_candidate, reg_def_use.block_last_def, reg_def_use.last_def_in_block, is_padding, simple_data_access_pattern, reg_def_use.live_var_used, straight_line_last_def, __agg_single2, inter_procedural_edge, init_symbol_minus_symbol_candidate_arm, function_inference.function_entry_initial, block_heuristic, hi_load_prop, unresolved_interval_order, symbolic_expr_from_relocation, discarded_split_load, likely_fallthrough, block_boundaries, call_tls_get_addr_mips, stack_def_use.block_last_def, __agg_single6, stack_def_use.live_var_at_block_end, split_load_point, cmp_reg_to_reg, unlikely_have_symbolic_immediate, reg_def_use.defined_in_block, jump_table_target, no_return_call, split_load_for_symbolization, call_tls_get_addr, __agg_subclause3, next_start, stack_def_use.ref_in_block, straight_line_def_used, def_used_for_address, init_ldr_add_pc, last_value_reg_limit, value_reg_edge, data_segment, common_tail, reg_def_use.ref_in_block, known_block, negative_block_heuristic, relative_jump_table_entry_candidate, stack_def_use.live_var_used, unresolved_block, block_last_instruction, value_reg_limit, composite_data_access

local_dynamic_tls_candidate(EA_lui:address, EA_lo:address, Index_lo:operand_index, Disp:number)

Candidates for Local Dynamic TLS model

• Uses: arch.memory_access, arch.move_reg_reg, arch.reg_arithmetic_operation, arch.reg_reg_arithmetic_operation, hi_load, next

• Used by: symbolic_operand_attribute, tls_relative_operand

• Recursive: arm_jump_table_cmp_limit, value_reg_unsupported, value_reg, candidate_block_is_not_padding, gp_relative_operand, split_load_total_points, stack_def_use.def_used, indexed_pc_relative_load, branch_to_calculated_pc_rel_addr, code_in_block, jump_table_element_access, compare_and_jump_register, jump_table_candidate, invalid, block_candidate_boundaries, data_in_code_propagate, relocation_adjustment_total, arch.simple_data_load, local_dynamic_tls_candidate, block_limit, block_instruction_next, reg_def_use.used, wis_memo, stack_def_use.live_var_used_in_block, wis_has_prior, arm_jump_table_skip_first_entry, wis_schedule, flags_and_jump_pair, litpool_symbolic_operand, segment_target_range, inferred_main_in_reg, code_in_block_candidate_refined, unresolved_interval, code_in_block_candidate, reg_def_use.return_val_used, start_function, correlated_live_reg, indexed_pc_relative_load_relative, arm_jump_table_block_start, arch.reg_relative_load, arm_jump_table_data_block, next_block_in_byte_interval, impossible_block, reg_def_use.ambiguous_last_def_in_block, reg_def_use.live_var_at_prior_used, data_block_candidate, invalid_jump_table_candidate, compare_and_jump_indirect, reg_def_use.flow_def, arm_jump_table_data_block_limit, stack_base_reg_move, __agg_single3, base_relative_jump, arm_jump_table_block_instruction, __agg_subclause2, no_value_reg_limit, overlap_with_litpool, split_load_candidate, __agg_subclause4, padding_block_candidate, inferred_main_dispatch, relocation_adjustment, tls_get_addr, after_end, stack_def_use.defined_in_block, reg_def_use.used_in_block, stack_def_use.last_def_in_block, candidate_block_is_padding, plt_entry, jump_table_max, reg_def_use.live_var_at_block_end, initialized_data_segment, tls_relative_operand_mips, relative_address, litpool_ref, arm_jump_table_candidate_start, must_fallthrough, may_fallthrough, contains_implausible_instr_seq, __agg_subclause6, no_return_call_refined, block_points_proportional, no_return_block, cinf_ldr_add_pc, relative_address_start, adjusts_stack_in_block, resolved_reaches, block_total_points, next_end, possible_target_from, block_candidate_dependency_edge, block, self_contained_segment, block_next, reg_def_use.live_var_def, jump_table_signed, reg_has_got, no_return_call_propagated, wis_prior, split_load_conflict, jump_table_start, wis_schedule_iter, reg_def_use.ambiguous_block_last_def, jump_table_prelude, first_block_in_byte_interval, arch.extend_load, base_relative_operation, indefinite_litpool_ref, compare_and_jump_immediate, unresolved_block_overlap, split_load, stack_def_use.used_in_block, reg_reg_arithmetic_operation_defs, padding_block_limit, reg_def_use.def_used, tls_desc_call, litpool_boundaries, discarded_block, stack_def_use.live_var_def, base_relative_operand, data_in_code, plt_block, reg_used_for, overlapping_instruction, reg_has_base_image, cmp_defines, nop_in_padding_candidate, compare_and_jump_indirect_op_valid, data_block_limit, __agg_subclause7, block_implies_block, const_value_reg_used, reg_def_use.return_block_end, next_type, __agg_single10, adrp_used, symbol_minus_symbol_litpool_access_pattern, contains_plausible_instr_seq, got_relative_operand, jump_table_candidate_refined, stack_def_use.live_var_at_prior_used, possible_target, instruction_memory_access_size, block_points, basic_target, split_load_operand, incomplete_block, transition_block_limit, data_access, litpool_confidence, block_overlap, arm_jump_table_candidate, reg_def_use.block_last_def, reg_def_use.last_def_in_block, is_padding, simple_data_access_pattern, reg_def_use.live_var_used, straight_line_last_def, __agg_single2, inter_procedural_edge, init_symbol_minus_symbol_candidate_arm, function_inference.function_entry_initial, block_heuristic, hi_load_prop, unresolved_interval_order, symbolic_expr_from_relocation, discarded_split_load, likely_fallthrough, block_boundaries, call_tls_get_addr_mips, stack_def_use.block_last_def, __agg_single6, stack_def_use.live_var_at_block_end, split_load_point, cmp_reg_to_reg, unlikely_have_symbolic_immediate, reg_def_use.defined_in_block, jump_table_target, no_return_call, split_load_for_symbolization, call_tls_get_addr, __agg_subclause3, next_start, stack_def_use.ref_in_block, straight_line_def_used, def_used_for_address, init_ldr_add_pc, last_value_reg_limit, value_reg_edge, data_segment, common_tail, reg_def_use.ref_in_block, known_block, negative_block_heuristic, relative_jump_table_entry_candidate, stack_def_use.live_var_used, unresolved_block, block_last_instruction, value_reg_limit, composite_data_access

local_dynamic_tls_base(EA:address)

Heuristic to infer the base address for the Local Dynamic TLS model

The base address is used to compute the addresses of TLS variables. There is no direct way of extracting the base address statically.

This heuristic selects the smallest disp (see local_dynamic_tls_candidate) and the smallest TLS symbol address among available symbols, assuming they correspond, and infers the base address from that.

NOTE: This approach may be inaccurate if the TLS variable with the smallest address does not appear in the binary.

• Uses: __agg_single6, __agg_single7, defined_symbol

• Used by: +disconnected2, tls_relative_operand

tls_pointer_reg_at(EA:address, Reg:register)

At EA, the TLS pointer is stored in Reg.

• Uses: arch.move_reg_reg, instruction, reg_def_use.def_used

• Used by: local_exec_tls_candidate

local_exec_tls_candidate(EA_lui:address, EA_lo:address, Index_lo:operand_index, Disp:number)

Candidates for Local Exec TLS model

• Uses: arch.memory_access, arch.reg_arithmetic_operation, instruction, op_immediate_and_reg, reg_def_use.def_used, tls_pointer_reg_at

• Used by: __agg_single8, symbolic_operand_attribute, tls_relative_operand

local_exec_tls_base(EA:address)

Heuristic to infer the base address for the Local Exec TLS model

The base address is used to compute the addresses of TLS variables. There is no direct way of extracting the base address statically.

This heuristic selects the smallest disp (see local_exec_tls_candidate) and the smallest TLS symbol address among available symbols, assuming they correspond, and infers the base address from that.

NOTE: This approach may be inaccurate if the TLS variable with the smallest address does not appear in the binary.

• Uses: __agg_single7, __agg_single8, defined_symbol

• Used by: +disconnected4, tls_relative_operand