mips startup stub

mipsevm/maketests.py

 #!/usr/bin/env python3
 import os
+import sys
+import tempfile
 from capstone import *
-md = Cs(CS_ARCH_MIPS, CS_MODE_32 + CS_MODE_BIG_ENDIAN)
 from elftools.elf.elffile import ELFFile
-os.makedirs("/tmp/mips", exist_ok=True)
-path = "/Users/kafka/fun/mips/mips-gcc-4.8.1/bin/"
-
-# Tests from:
-# https://github.com/grantae/OpenMIPS/blob/master/software/test/macro/tests/addiu/src/os/khi/addiu.asm
-
-for d in os.listdir("test/"):
-  if not d.endswith(".asm"):
-    continue
-  print("building", d)
-  # which mips is go
-  os.system("%s/mips-elf-as -defsym big_endian=1 -march=mips32r2 -o /tmp/mips/%s test/%s" % (path, d, d))
-  elffile = ELFFile(open("/tmp/mips/"+d, "rb"))
-  #print(elffile)
-  for sec in elffile.iter_sections():
-    #print(sec, sec.name, sec.data())
-    if sec.name == ".test":
-      with open("test/bin/"+(d.replace(".asm", ".bin")), "wb") as f:
-        # jump to 0xdead0000 when done
-        #data = b"\x24\x1f\xde\xad\x00\x1f\xfc\x00" + sec.data()
-        data = sec.data()
-        for dd in md.disasm(data, 0):
-          print(dd)
-        f.write(data)
+md = Cs(CS_ARCH_MIPS, CS_MODE_32 + CS_MODE_BIG_ENDIAN)
 
+def maketest(d, out):
+  with tempfile.NamedTemporaryFile() as nf:
+    path = "/Users/kafka/fun/mips/mips-gcc-4.8.1/bin/"
+    print("building", d, "->", out)
+    # which mips is go
+    ret = os.system("%s/mips-elf-as -defsym big_endian=1 -march=mips32r2 -o %s %s" % (path, nf.name, d))
+    assert(ret == 0)
+    nf.seek(0)
+    elffile = ELFFile(nf)
+    #print(elffile)
+    for sec in elffile.iter_sections():
+      #print(sec, sec.name, sec.data())
+      if sec.name == ".test":
+        with open(out, "wb") as f:
+          # jump to 0xdead0000 when done
+          #data = b"\x24\x1f\xde\xad\x00\x1f\xfc\x00" + sec.data()
+          data = sec.data()
+          for dd in md.disasm(data, 0):
+            print(dd)
+          f.write(data)
 
+if __name__ == "__main__":
+  os.makedirs("/tmp/mips", exist_ok=True)
+  if len(sys.argv) > 2:
+    maketest(sys.argv[1], sys.argv[2])
+  else:
+    for d in os.listdir("test/"):
+      if not d.endswith(".asm"):
+        continue
+      maketest("test/"+d, "test/bin/"+(d.replace(".asm", ".bin")))
\ No newline at end of file

risc/run.py

@@ -8,6 +8,7 @@ import traceback
 from elftools.elf.elffile import ELFFile
 from capstone import *
 md = Cs(CS_ARCH_MIPS, CS_MODE_32 + CS_MODE_BIG_ENDIAN)
+tracelevel = int(os.getenv("TRACE", 0))
 
 from termcolor import colored, cprint
 from hexdump import hexdump
@@ -54,7 +55,7 @@ def hook_code_simple(uc, address, size, user_data):
         dat = "EMPTY BASIC BLOCK?!?"
       #instructions_seen.add(dat.mnemonic)
       #print(sorted(list(instructions_seen)))
-      print("%10d(%2d): %8x %-80s %s" % (icount, newicount, address, r[address], dat))
+      print("%10d(%2d): %8x %-80s %s" % (icount, newicount, address, r[address] if address in r else "UNKNOWN", dat))
     icount += newicount
     bcount += 1
     return True
@@ -66,7 +67,6 @@ def hook_code_simple(uc, address, size, user_data):
 def start_instrumenting():
   global instrumenting, instrumenting_all
   if not instrumenting:
-    tracelevel = int(os.getenv("TRACE", 0))
     if tracelevel >= 2:
       mu.hook_add(UC_HOOK_CODE, hook_code_simple, user_data=mu)
     elif tracelevel == 1:
@@ -304,19 +304,26 @@ for seg in elffile.iter_segments():
   mu.mem_write(seg.header.p_vaddr, seg.data())
 
 entry = elffile.header.e_entry
-print("entrypoint: %x" % entry)
+print("entrypoint: 0x%x" % entry)
 #hexdump(mu.mem_read(entry, 0x10))
 
+"""
 mu.reg_write(UC_MIPS_REG_SP, stack_start-0x2000)
 
 # http://articles.manugarg.com/aboutelfauxiliaryvectors.html
 _AT_PAGESZ = 6
-mu.mem_write(stack_start-0x2000, struct.pack(">IIIIIIII",
-  1,  # argc
-  stack_start-0x1000, 0,  # argv
-  stack_start-0x400, 0,  # envp
+mu.mem_write(stack_start-0x2000, struct.pack(">IIIIII",
+  0,  # argc
+  0,  # argv
+  0,  # envp
   _AT_PAGESZ, 0x1000, 0)) # auxv
 mu.mem_write(stack_start-0x400, b"GOGC=off\x00")
+"""
+
+# moved to MIPS
+start = open("startup.bin", "rb").read() + struct.pack(">I", entry)
+mu.mem_write(0, start)
+entry = 0
 
 r = RangeTree()
 for section in elffile.iter_sections():
@@ -359,8 +366,11 @@ mu.hook_add(UC_HOOK_MEM_FETCH_UNMAPPED, hook_mem_invalid)
 mu.hook_add(UC_HOOK_INTR, hook_interrupt)
 #mu.hook_add(UC_HOOK_INSN, hook_interrupt, None, 1, 0, 0x0c000000)
 
+if tracelevel == 4:
+  start_instrumenting()
+
 try:
-  mu.emu_start(entry, 0)
+  mu.emu_start(entry, SIZE)
 except unicorn.UcError:
   pass
 

risc/startup.s

+    .section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+test:
+
+lui     $sp, 0x7fff
+ori     $sp, 0xd000
+
+ori $t0, $0, 6
+sw $t0, 0xC($sp)
+ori $t0, $0, 0x1000
+sw $t0, 0x10($sp)
+
+lw $ra, dat($0)
+jr $ra
+nop
+
+dat:
+
+.end test

risc/startup.sh

+#!/bin/bash -e
+../mipsevm/maketests.py ../risc/startup.s ../risc/startup.bin