priv: added __main__ script to module which correctly configures the cpu depending on --kernel or --image options

riscemu/priv/ImageLoader.py

@@ -2,7 +2,7 @@
 Laods a memory image with debug information into memory
 """
 
-from ..MMU import MMU
+from .PrivMMU import PrivMMU
 from ..Config import RunConfig
 from ..Executable import Executable, LoadedExecutable, LoadedMemorySection, LoadedInstruction, MemoryFlags
 from .ElfLoader import ElfInstruction, ElfLoadedMemorySection, InstructionAccessFault, InstructionAddressMisalignedTrap
@@ -10,6 +10,7 @@ from ..decoder import decode
 from ..IO.IOModule import IOModule
 from .privmodes import PrivModes
 from ..colors import FMT_ERROR, FMT_NONE
+import json
 
 from functools import lru_cache
 from typing import Dict, List, Tuple, Optional, TYPE_CHECKING
@@ -18,26 +19,37 @@ if TYPE_CHECKING:
     from .PrivCPU import PrivCPU
 
 
-class ContinuousMMU(MMU):
+class MemoryImageMMU(PrivMMU):
     io: List[IOModule]
     data: bytearray
     io_start: int
-    debug_info: Dict[str, Dict[str, str]]
+    debug_info: Dict[str, Dict[str, Dict[str, str]]]
+
+    def __init__(self, file_name: str, io_start: int = 0xFF0000):
+        super(MemoryImageMMU, self).__init__(conf=RunConfig())
+
+        with open(file_name, 'rb') as memf:
+            data = memf.read()
+        with open(file_name + '.dbg', 'r') as dbgf:
+            debug_info: Dict = json.load(dbgf)
 
-    def __init__(self, data: bytes, debug_info: Dict, cpu, io_start: int = 0xFF0000):
-        super(ContinuousMMU, self).__init__(conf=RunConfig())
-        self.cpu: 'PrivCPU' = cpu
         self.data = bytearray(data)
+        # TODO: super wasteful memory allocation happening here
         if len(data) < io_start:
             self.data += bytearray(io_start - len(data))
         self.debug_info = debug_info
         self.io_start = io_start
         self.io = list()
-        self.kernel_end = 0
-        for start, name in debug_info['sections'].items():
-            if name.startswith('programs'):
-                self.kernel_end = int(start)
-                break
+
+    def get_entrypoint(self):
+        try:
+            start = self.debug_info['symbols']['kernel'].get('_start', None)
+            if start is not None:
+                return start
+            return self.debug_info['symbols']['kernel'].get('_ftext')
+        except KeyError:
+            print(FMT_ERROR + '[MMU] cannot find kernel entry in debug information! Falling back to 0x100' + FMT_NONE)
+            return 0x100
 
     @lru_cache(maxsize=2048)
     def read_ins(self, addr: int) -> ElfInstruction:
@@ -66,13 +78,6 @@ class ContinuousMMU(MMU):
             print(FMT_ERROR + "[MMU] possible null dereference (write {:x}) from (pc={:x},sec={},rel={:x})".format(
                 addr, pc, text_sec.owner + ':' + text_sec.name, pc - text_sec.base
             ) + FMT_NONE)
-        if addr < self.kernel_end:
-            if self.cpu.mode != PrivModes.MACHINE:
-                pc = self.cpu.pc
-                text_sec = self.get_sec_containing(pc)
-                print(FMT_ERROR + "[MMU] kernel access to {:x} from outside kernel mode! (pc={:x},sec={},rel={:x})".format(
-                    addr, pc, text_sec.owner + ':' + text_sec.name, pc - text_sec.base
-                ) + FMT_NONE)
 
         if addr >= self.io_start:
             return self.io_at(addr).write(addr, data, size)
@@ -88,7 +93,7 @@ class ContinuousMMU(MMU):
         self.io.append(io)
 
     def __repr__(self):
-        return "ImageMMU()"
+        return "MemoryImageMMU()"
 
     @lru_cache(maxsize=32)
     def get_sec_containing(self, addr: int) -> Optional[LoadedMemorySection]:

riscemu/priv/PrivCPU.py

@@ -8,7 +8,7 @@ import time
 from riscemu.CPU import *
 from .CSR import CSR
 from .ElfLoader import ElfExecutable
-from .ImageLoader import ContinuousMMU
+from .ImageLoader import MemoryImageMMU
 from .Exceptions import *
 from .PrivMMU import PrivMMU
 from ..IO import TextIO
@@ -47,22 +47,19 @@ class PrivCPU(CPU):
     the equivalent of "1 byte" (this is actually impossible)
     """
 
-    def __init__(self, conf):
+    def __init__(self, conf, mmu: PrivMMU):
         super().__init__(conf, [PrivRV32I, RV32M])
         self.mode: PrivModes = PrivModes.MACHINE
 
-        with open('mem.img', 'rb') as memf:
-            data = memf.read()
-        with open('mem.img.dbg', 'r') as dbgf:
-            debug_info = json.load(dbgf)
+        mmu.set_cpu(self)
+        self.pc = mmu.get_entrypoint()
+        self.mmu = mmu
 
-        self.mmu = ContinuousMMU(data, debug_info, self)
-        self.pc = 0x100
-        self.mmu.add_io(TextIO.TextIO(0xff0000, 64))
-        self.syscall_int = None
+        if hasattr(self.mmu, 'add_io'):
+            self.mmu.add_io(TextIO.TextIO(0xff0000, 64))
 
+        self.syscall_int = None
         self.launch_debug = False
-
         self.pending_traps: List[CpuTrap] = list()
 
         self._time_start = 0
@@ -87,7 +84,7 @@ class PrivCPU(CPU):
                 self.launch_debug = True
                 self.pc += self.INS_XLEN
             else:
-                print(FMT_ERROR + "[CPU] excpetion caught at 0x{:08X}: {}:".format(self.pc - 1, ins) + FMT_NONE)
+                print(FMT_ERROR + "[CPU] exception caught at 0x{:08X}: {}:".format(self.pc - 1, ins) + FMT_NONE)
                 print(ex.message())
                 if self.conf.debug_on_exception:
                     self.launch_debug = True

riscemu/priv/PrivMMU.py

@@ -1,13 +1,29 @@
 from ..MMU import *
+from abc import abstractmethod
 
 import typing
 
 from .ElfLoader import ElfExecutable
 
+if typing.TYPE_CHECKING:
+    from .PrivCPU import PrivCPU
+
 
 class PrivMMU(MMU):
+    cpu: 'PrivCPU'
+
+    @abstractmethod
+    def get_entrypoint(self) -> int:
+        raise
+
+    def set_cpu(self, cpu: 'PrivCPU'):
+        self.cpu = cpu
+
+
+class LoadedElfMMU(PrivMMU):
     def __init__(self, elf: ElfExecutable):
-        super(PrivMMU, self).__init__(conf=RunConfig())
+        super().__init__(conf=RunConfig())
+        self.entrypoint = elf.symbols['_start']
 
         self.binaries.append(elf)
         for sec in elf.sections:
@@ -18,3 +34,6 @@ class PrivMMU(MMU):
 
     def allocate_section(self, name: str, req_size: int, flag: MemoryFlags):
         raise NotImplementedError("Not supported!")
+
+    def get_entrypoint(self):
+        return self.entrypoint

riscemu/priv/__main__.py

@@ -1,4 +1,7 @@
 from .PrivCPU import PrivCPU, RunConfig
+from .ImageLoader import MemoryImageMMU
+from .PrivMMU import LoadedElfMMU
+from .ElfLoader import ElfExecutable
 
 from ..Tokenizer import RiscVInput
 from ..ExecutableParser import ExecutableParser
@@ -8,14 +11,23 @@ import sys
 if __name__ == '__main__':
     import argparse
 
-    #parser = argparse.ArgumentParser(description='RISC-V privileged architecture emulator', prog='riscemu')
+    parser = argparse.ArgumentParser(description='RISC-V privileged architecture emulator', prog='riscemu')
 
-    #parser.add_argument('--kernel', type=str, help='Kernel elf loaded with user programs', nargs='?')
-    #parser.add_argument('--image', type=str, help='Memory image containing kernel', nargs='?')
+    parser.add_argument('--kernel', type=str, help='Kernel elf loaded with user programs', nargs='?')
+    parser.add_argument('--image', type=str, help='Memory image containing kernel', nargs='?')
 
-    #args = parser.parse_args()
+    args = parser.parse_args()
+    mmu = None
 
-    cpu = PrivCPU(RunConfig())
+    if args.kernel is not None:
+        mmu = LoadedElfMMU(ElfExecutable(args.kernel))
+    elif args.image is not None:
+        mmu = MemoryImageMMU(args.image)
+
+    if mmu is None:
+        print("You must specify one of --kernel or --image for running in privilege mode!")
+
+    cpu = PrivCPU(RunConfig(), mmu)
 
     cpu.run()