It doesn't even specify which "invalid syscall".
```
$ src/bitcoind -sandbox=log-and-abort
2022-02-17T13:45:57Z Bitcoin Core version v22.99.0-b223c3c21e89 (release build)
2022-02-17T13:45:57Z Assuming ancestors of block 00000000000000000008a89e854d57e5667df88f1cdef6fde2fbca1de5b639ad have valid signatures.
2022-02-17T13:45:57Z Setting nMinimumChainWork=00000000000000000000000000000000000000001fa4663bbbe19f82de910280
2022-02-17T13:45:57Z Experimental syscall sandbox enabled (-sandbox=log-and-abort): bitcoind will terminate if an unexpected (not allowlisted) syscall is invoked.
2022-02-17T13:45:57Z Using the 'sse4(1way),sse41(4way),avx2(8way)' SHA256 implementation
2022-02-17T13:45:57Z Default data directory /…/.bitcoin
2022-02-17T13:45:57Z Using data directory /…/.bitcoin
2022-02-17T13:45:57Z Config file: /…/.bitcoin/bitcoin.conf (not found, skipping)
2022-02-17T13:45:57Z Command-line arg: sandbox="log-and-abort"
2022-02-17T13:45:57Z Using at most 125 automatic connections (1024 file descriptors available)
2022-02-17T13:45:57Z Using 16 MiB out of 32/2 requested for signature cache, able to store 524288 elements
2022-02-17T13:45:57Z Using 16 MiB out of 32/2 requested for script execution cache, able to store 524288 elements
2022-02-17T13:45:57Z Script verification uses 1 additional threads
Bad system call (core dumped)
```
Nothing in `dmesg` either.
break;
    case SyscallSandboxPolicy::VALIDATION_SCRIPT_CHECK: 
        break;
    case SyscallSandboxPolicy::SHUTOFF: 
        seccomp_policy_builder.AllowFileSystem();
        break;
    }
    const SyscallSandboxAction default_action = g_syscall_sandbox_log_violation_before_terminating ? SyscallSandboxAction::INVOKE_SIGNAL_HANDLER : SyscallSandboxAction::KILL_PROCESS;
    std::vector<sock_filter> filter = seccomp_policy_builder.BuildFilter(default_action);
    const sock_fprog prog = {
        .len = static_cast<uint16_t>(filter.size()),
        .filter = filter.data(),
    };
    
    
    
    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
        throw std::runtime_error("Syscall sandbox enforcement failed: prctl(PR_SET_NO_NEW_PRIVS)");
    }
    
    
    
    if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) != 0) {
        throw std::runtime_error("Syscall sandbox enforcement failed: prctl(PR_SET_SECCOMP)");
    }
    const std::string thread_name = !util::ThreadGetInternalName().empty() ? util::ThreadGetInternalName() : "*unnamed*";
    LogPrint(BCLog::UTIL, "Syscall filter installed for thread \"%s\"\n", thread_name);
#endif 
}