DebugMemWrite8 segfaults when debugger isnt properly setup

[Mai-Lapyst]

When trying to call DebugMemWrite8 before setting up the debugger correctly via init_debugger, the function dosnt return M64ERR_INVALID_STATE like other functions like DebugStep, but rather segfaults when trying to read the instruction at the pc in cp0_update_count.

Example code:

if (CoreStartup( coreApiVersion, NULL, NULL, NULL, NULL, NULL, NULL ) != M64ERR_SUCCESS) {
  throw std::runtime_error("failed to start core");
}

auto r = DebugMemWrite8(0x00, 127); // this segfaults!
std::cout << "result of write: " << (int) r << std::endl;

Stacktrace:

[0] from 0x00005555555a7370 in cp0_update_count+48 at mupen64plus-core/src/device/r4300/cp0.c:160
[1] from 0x00005555555a7459 in TLB_refill_exception+73 at mupen64plus-core/src/device/r4300/cp0.c:220
[2] from 0x00005555555a6fb0 in virtual_to_physical_address+176 at mupen64plus-core/src/device/r4300/tlb.c:143
[3] from 0x00005555555a8026 in r4300_write_aligned_word+70 at mupen64plus-core/src/device/r4300/r4300_core.c:360
[4] from 0x00005555555a2019 in write_memory_8+89 at mupen64plus-core/src/debugger/dbg_memory.c:364
[5] from 0x0000555555583d7c in DebugMemWrite8+44 at mupen64plus-core/src/api/debugger.c:347

[richard42]

I think that in this case, the reason for the segfault is not that the debugger is not yet initialized, but that the CPU is not yet initialized.