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linux_demon: PTRACE_EVENT_STOPs can sometimes be reported even if a thread has already hit a trap (e.g. a trap net or breakpoint trap). this would sometimes cause spurious SIGTRAPs after issuing a PTRACE_INTERRUPT - so we need to flag halted threads to not treat that as a 'real' trap. furthermore, even though that trap was hit, it does not guarantee that the debugger would next see a SIGTRAP. that would cause spurious SIGILLs, because we'd resume threads *after* the trap, despite not seeing the trap, so they'd just see a malformed instruction (the bytes subsequent the initial trap). so in those cases, we need to roll such threads back, so that they re-execute the trap, and so that we see a regular SIGTRAP, and handle the trap correctly.
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Ryan Fleury committed
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@@ -1770,6 +1770,7 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
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{
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if(n->v != thread && n->v->state == LNX_DMN_ThreadState_Running)
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{
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n->v->ghost_trap = 1;
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if(LNX_RETRY_ON_EINTR(ptrace(PTRACE_INTERRUPT, n->v->tid, 0, 0)) < 0)
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{
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log_infof("ptrace error: Couldn't send PTRACE_INTERRUPT to TID %I64u.", n->v->tid);
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@@ -2029,16 +2030,23 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
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if(hit_user_trap)
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{
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U64 ip = lnx_dmn_ip_from_thread(thread);
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lnx_dmn_thread_write_ip(thread, ip - 1);
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lnx_dmn_thread_write_ip(thread, ip - arch_info->trap_instruction.size);
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}
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// rjf: generate event
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DMN_Event *e = dmn_event_list_push(arena, &events);
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e->kind = hit_user_trap ? DMN_EventKind_Breakpoint : DMN_EventKind_Trap;
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e->process = lnx_dmn_handle_from_process(process);
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e->thread = lnx_dmn_handle_from_thread(thread);
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e->instruction_pointer = lnx_dmn_ip_from_thread(thread);
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e->user_data = hit_user_trap ? hit_user_trap->id : 0;
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// rjf: generate event, if this isn't a ghost trap
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if(thread->ghost_trap)
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{
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thread->ghost_trap = 0;
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}
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else
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{
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DMN_Event *e = dmn_event_list_push(arena, &events);
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e->kind = hit_user_trap ? DMN_EventKind_Breakpoint : DMN_EventKind_Trap;
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e->process = lnx_dmn_handle_from_process(process);
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e->thread = lnx_dmn_handle_from_thread(thread);
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e->instruction_pointer = lnx_dmn_ip_from_thread(thread);
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e->user_data = hit_user_trap ? hit_user_trap->id : 0;
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}
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}
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}break;
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@@ -2223,6 +2231,26 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
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e->tls_root_vaddr = thread->dtv_base_vaddr;
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}
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// rjf: stop event for other threads we're attached to, due to a stop in
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// another thread - check if this hit a trap and roll back
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else if(thread != 0 && thread->state == LNX_DMN_ThreadState_Stopped)
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{
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//- rjf: unpack thread IP / process
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U64 ip = lnx_dmn_ip_from_thread(thread);
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DMN_Handle process_handle = lnx_dmn_handle_from_process(process);
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//- rjf: check previous bytes against trap instruction. if this thread
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// executed a trap, we need to roll back before continuing this thread.
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// we CANNOT RELY on there being a subsequently-queued SIGTRAP.
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U8 *hit_trap_bytes_maybe = push_array(scratch.arena, U8, arch_info->trap_instruction.size);
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dmn_process_read(process_handle, r1u64(ip - arch_info->trap_instruction.size, ip), hit_trap_bytes_maybe);
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String8 hit_trap_data_maybe = str8(hit_trap_bytes_maybe, arch_info->trap_instruction.size);
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if(str8_match(hit_trap_data_maybe, arch_info->trap_instruction, 0))
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{
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lnx_dmn_thread_write_ip(thread, ip - arch_info->trap_instruction.size);
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}
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}
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// rjf: stop event for unrecognized thread -> this references a thread we
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// haven't seen cloned yet (we cannot rely on the order of clone/stop). so,
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// we will gather the ID, and increase the pending threads count, and stop
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@@ -2263,44 +2291,42 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
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//
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else
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{
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LNX_DMN_Thread *thread = lnx_dmn_thread_from_pid(wait_id);
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thread->pass_through_signal = 1;
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thread->pass_through_signo = wstopsig;
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local_persist B8 is_repeatable[] =
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{
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0, // null
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1, // 1 SIGHUP
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1, // 2 SIGINT
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1, // 3 SIGQUIT
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1, // 4 SIGTRAP
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1, // 5 SIGABRT
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1, // 6 SIGIOT
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1, // 7 SIGBUS
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1, // 8 SIGFPE
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1, // 9 SIGKILL
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1, // 10 SIGUSR1
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1, // 11 SIGSEGV
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1, // 12 SIGUSR2
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1, // 13 SIGPIPE
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1, // 14 SIGALRM
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1, // 15 SIGTERM
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1, // 16 SIGTKFLT
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0, // 17 SIGCHLD
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0, // 18 SIGCONT
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1, // 19 SIGSTOP
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1, // 20 SIGTSP
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1, // 21 SIGTTIN
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1, // 22 SIGTTOU
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0, // 23 SIGURG
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1, // 24 SIGXCPU
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1, // 25 SIGXFSZ
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1, // 26 SIGVTALRM
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1, // 27 SIGPROF
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0, // 28 SIGWINCH
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1, // 29 SIGIO
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1, // 30 SIGPWR
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1, // 31 SIGSYS
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1, // 32 SIGUNUSED
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1, // SIGHUP 1
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1, // SIGINT 2
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1, // SIGQUIT 3
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1, // SIGILL 4
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1, // SIGTRAP 5
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1, // SIGABRT/SIGIOT 6
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1, // SIGBUS 7
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1, // SIGFPE 8
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1, // SIGKILL 9
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1, // SIGUSR1 10
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1, // SIGSEGV 11
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1, // SIGUSR2 12
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1, // SIGPIPE 13
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1, // SIGALRM 14
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1, // SIGTERM 15
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1, // SIGSTKFLT 16
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0, // SIGCHLD 17
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0, // SIGCONT 18
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1, // SIGSTOP 19
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1, // SIGTSTP 20
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1, // SIGTTIN 21
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1, // SIGTTOU 22
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0, // SIGURG 23
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1, // SIGXCPU 24
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1, // SIGXFSZ 25
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1, // SIGVTALRM 26
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1, // SIGPROF 27
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0, // SIGWINCH 28
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1, // SIGIO 29
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1, // SIGPWR 30
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1, // SIGSYS/SIGUNUSED31
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};
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DMN_Event *e = dmn_event_list_push(arena, &events);
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e->kind = DMN_EventKind_Exception;
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@@ -178,6 +178,7 @@ struct LNX_DMN_Thread
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void *reg_block;
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B32 is_reg_block_dirty;
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B32 pass_through_signal;
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B32 ghost_trap;
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U64 pass_through_signo;
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U64 orig_rax;
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U64 dtv_base_vaddr;
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@@ -7,23 +7,24 @@
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// initial alpha:
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// [x] .so loading/debugging - missing debug info
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// [x] missing disasm
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// [ ] recycling semaphore files - or alt strat?
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// [ ] control
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// [ ] multithreaded stepping - trap hits reported on other threads.
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// [ ] stale memory - things evaluating to stale values that are definitely not zero
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// [ ] support
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// [ ] .eh_frame unwinding without .eh_frame_hdr
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// [ ] asan
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// [ ] stale memory - things evaluating to stale values that are definitely not zero
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// [ ] rendering
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// [ ] bitmaps / geometry
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// [ ] bitmaps / geometry
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//
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// post initial alpha:
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// [ ] windowing
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// [ ] wayland
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// [ ] support
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// [ ] .eh_frame unwinding without .eh_frame_hdr
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//
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// [x] clipboard
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// [x] jai exes - busted call stacks / unwind info / paths?
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// [x] statically linked EXEs - busted unwinding
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// [x] statically linked EXEs, not parsing maps file correctly
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// [x] asan
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// [x] multithreaded stepping - trap hits reported on other threads.
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////////////////////////////////
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//~ rjf: evaluation system pass TODO notes
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