Method _callSyscall

KittyMemoryEx/KittyTrace.cpp:663–875

    if (_autoRestoreRegs)
        setRegs(&backup_regs);

    KITTY_LOGD("callFunction: Calling function %p returned %p.", (void *)functionAddress, (void *)result.result.ptr);

    return result;
}

kitty_rp_call_t KittyTraceMgr::_callSyscall(long sysnr, int nargs, ...)
{
    if (!_attached || _pid <= 0)
        return {KT_RP_CALL_FAILED, {0}};

    user_regs_struct backup_regs, return_regs, tmp_regs;
    memset(&backup_regs, 0, sizeof(backup_regs));
    memset(&return_regs, 0, sizeof(return_regs));
    memset(&tmp_regs, 0, sizeof(tmp_regs));

    // backup current regs
    if (!getRegs(&backup_regs))
    {
        KITTY_LOGE("callSyscall(%d): Failed, couldn't get regs.", int(sysnr));
        return {KT_RP_CALL_REGS_FAILED, {0}};
    }

    memcpy(&tmp_regs, &backup_regs, sizeof(backup_regs));

    KT_REGS_ALIGN_STACK(backup_regs);
    KT_REGS_ALIGN_STACK(tmp_regs);
    KT_REGS_ALIGN_STACK(return_regs);

    std::vector<uintptr_t> vargs(6, 0);
    if (nargs > 0)
    {
        va_list vl;
        va_start(vl, nargs);
        for (int i = 0; i < nargs; i++)
        {
            vargs[i] = va_arg(vl, uintptr_t);
        }
        va_end(vl);
    }

    KITTY_LOGD("callSyscall(%d, 0x%zx, 0x%zx, 0x%zx, 0x%zx, 0x%zx, 0x%zx)",
               int(sysnr),
               vargs[0],
               vargs[1],
               vargs[2],
               vargs[3],
               vargs[4],
               vargs[5]);

    uintptr_t target_pc_mem = tmp_regs.KT_REG_PC;
    std::vector<uint8_t> syscall_code;
    std::vector<uint8_t> backup_code;
    if (_syscallGadget != 0)
    {
        KITTY_LOGD("callSyscall(%d) using syscall gadget at %p", int(sysnr), (void *)_syscallGadget);
        tmp_regs.KT_REG_PC = _syscallGadget;
    }