Metroid Samus Returns: boots into unknown thumb instruction

[Miepee]

Unknown Thumb instruction: Unknown instruction 0x42c6

Probably related to #23 ?

Unsure if the backtrace is of any use:

#0  0x00007ffff6eb213a in __cxxabiv1::__cxa_throw (obj=0x5555564274f0, tinfo=0x555555b49360 <typeinfo for std::runtime_error@GLIBCXX_3.4>, 
    dest=0x7ffff6ec9d50 <std::runtime_error::~runtime_error()>) at /usr/src/debug/gcc/gcc/libstdc++-v3/libsupc++/eh_throw.cc:81
#1  0x000055555560343f in Interpreter::HandlerStubThumb(Interpreter::CPUContext&, ARM::ThumbInstr, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) [clone .isra.0] [clone .cold] ()
#2  0x00005555556bc38d in void Interpreter::StepWithDispatchTable<&Interpreter::default_dispatch_table>(Interpreter::ExecutionContext&) ()
#3  0x00005555556bc460 in Interpreter::Interpreter::Run(Interpreter::ExecutionContext&, Interpreter::ProcessorController&, unsigned int, unsigned int) ()
#4  0x00005555557142ae in void boost::context::detail::fiber_entry<boost::context::detail::fiber_record<boost::context::fiber, boost::context::basic_fixedsize_stack<boost::context::stack_traits>, boost::coroutines2::detail::push_coroutine<void>::control_block::control_block<boost::context::basic_fixedsize_stack<boost::context::stack_traits>, HLE::OS::CoroutineThreadControl::CoroutineThreadControl<HLE::OS::Thread::Thread(HLE::OS::Process&, unsigned int, unsigned int)::{lambda()#1}>(HLE::OS::Thread::Thread(HLE::OS::Process&, unsigned int, unsigned int)::{lambda()#1}&&)::{lambda(boost::coroutines2::detail::pull_coroutine<void>&)#1}>(boost::context::preallocated, HLE::OS::Thread::Thread(HLE::OS::Process&, unsigned int, unsigned int)::{lambda()#1}&&, HLE::OS::CoroutineThreadControl::CoroutineThreadControl<HLE::OS::Thread::Thread(HLE::OS::Process&, unsigned int, unsigned int)::{lambda()#1}>(HLE::OS::Thread::Thread(HLE::OS::Process&, unsigned int, unsigned int)::{lambda()#1}&&)::{lambda(boost::coroutines2::detail::pull_coroutine<void>&)#1}&&)::{lambda(boost::context::fiber&&)#1}> >(boost::context::detail::transfer_t) ()
#5  0x00005555559c36bf in make_fcontext ()
#6  0x0000000000000000 in ?? ()

[neobrain]

Can you check the ARMv6 Architecture Reference Manual to see if it's a THUMB encoding of lsrs like in the issue you mentioned?

[Miepee]

I'm not that familiar with it, but doesn't seem like it?
From what I see in A6.7.37/38, LSRS either starts with 0b0000'1 or with ob0100'0000'11.
Where as 0x42C6 is 0b0100'0010'1100'0110

[Miepee]

Looking at A5.2.2 it looks more like a cmn

where Rm would be 0, and Rn would be 3

[neobrain]

Yup that seems to be the one. Mikage handles most THUMB instructions by converting the encoding to ARM and passing them to the interpreter like that, see thumb.cpp. Do you want to give adding CMN a try? :)

Some versions of the ARM ARM include the equivalent ARM encoding for THUMB instructions, which would help here.

[Miepee]

I can try but no promises that I'll produce something working xP
Would it be fine for you to invite @miepee:matrix.org to your room for follow up questions?

[neobrain]

I can try but no promises that I'll produce something working xP

You got this :)

Would it be fine for you to invite @Miepee:matrix.org to your room for follow up questions?

Sure, you should have an invitation!

[neobrain]

@Miepee Did you have any luck with this?

[Miepee]

No, haven't had the chance to try yet :(
I do want to dig into it, but dunno when I'll be able to.