start on mips emulator

risc/build.sh

 #!/bin/bash
 cd ../minigeth
-GOOS=linux GOARCH=riscv64 go build
+GOOS=linux GOARCH=mips go build
 cp go-ethereum ../risc/go-ethereum
 cd ../risc
 file go-ethereum

risc/run.py

+#!/usr/bin/env python3
+from elftools.elf.elffile import ELFFile
+
+from hexdump import hexdump
+from unicorn import *
+from unicorn.mips_const import *
+
+mu = Uc(UC_ARCH_MIPS, UC_MODE_32 + UC_MODE_BIG_ENDIAN)
+
+cnt = 0
+def hook_code(uc, address, size, user_data):
+  global cnt
+  cnt += 1
+  if cnt == 1000:
+    raise Exception("too many instructions")
+  try:
+    print(">>> Tracing instruction at 0x%x, instruction size = %u" % (address, size))
+    #print('    code hook: pc=%08x sp=%08x' % (
+    #  uc.reg_read(UC_MIPS_REG_PC),
+    #  uc.reg_read(UC_MIPS_REG_SP)
+    #  ))
+  except:
+    raise Exception("ctrl-c")
+
+elf = open("go-ethereum", "rb")
+data = elf.read()
+elf.seek(0)
+
+rte = data.find(b"\x08\x02\x2c\x95")
+print(hex(rte))
+
+elffile = ELFFile(elf)
+#for seg in elffile.iter_segments():
+#  print(seg.header, dir(seg.header))
+entry = elffile.header.e_entry
+print("entrypoint: %x" % entry)
+
+
+SIZE = 16*1024*1024
+
+mu.mem_map(0, SIZE)
+mu.mem_write(0x10000, data)
+
+hexdump(mu.mem_read(entry, 0x10))
+
+mu.reg_write(UC_MIPS_REG_SP, SIZE-4)
+
+mu.hook_add(UC_HOOK_CODE, hook_code, user_data=mu)
+mu.emu_start(entry, SIZE)