The over-engineered Golang runtime

[fwsGonzo]

Golang seems to have something that resembles a thread (sysmon) that is activated with signals, or something like that. Either way, there is no way around implemented signals, and there is a basic implementation in the emulator now with altstacks.

#0  runtime.rt_sigaction () at /go/src/runtime/sys_linux_riscv64.s:415
#1  0x00000000000428b8 in runtime.sysSigaction (sig=0, new=0xc000033ed8, old=0x0)
#2  0x0000000000058acc in runtime.sigaction (sig=0, new=0xc000033ed8, old=0x0)
    at /go/src/runtime/sigaction.go:15
#3  0x0000000000042738 in runtime.setsig (i=0, fn=0)
#4  0x000000000005bb30 in runtime.sigfwdgo (sig=0, info=0x0, ctx=0x17, ~r0=<optimized out>)
#5  0x000000000005a644 in runtime.sigtrampgo (sig=0, info=0x0, ctx=0x17)
#6  0x00000000000732e8 in runtime.sigtramp ()
#7  0x000000000004293c in runtime.signalM (mp=0x0, sig=0)

Unfortunately it seems to invoke signal 0, which doesn't have a handler (I assume). So, there is something wrong before hitting that call chain.

[fwsGonzo]

libriscv/emulator$ ./rvlinux ../binaries/go/program
Unhandled system call: 123
hello world
>>> Program exited, exit code = 0 (0x0)
Instructions executed: 792674
Pages in use: 252 (1008 kB memory)

By ignoring signal=0 it seems to run through main.