add devmemd to access remote systems

coresight-tools/devmemd.py

@@ -0,0 +1,176 @@
+#!/usr/bin/python
+
+"""
+Client for devmemd, the simple daemon to handle /dev/mem
+requests from a remote machine.
+
+When run as a main program, this script provides a simple
+command shell supporting read and write commands.
+
+Copyright (C) ARM Ltd. 2021.  All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from __future__ import print_function
+
+import sys, socket, struct
+
+# devmemd request codes: see devmemd.c
+REQ_NOP     = 0
+REQ_READ    = 1
+REQ_WRITE   = 2
+REQ_CLOSE   = 3
+REQ_NOISE   = 4
+REQ_RESET   = 5
+REQ_PAGE    = 6
+
+# devmemd response codes: see devmemd.c
+ERR_OK      = 0
+ERR_MMAP    = 1
+ERR_ALIGN   = 2
+ERR_BADREQ  = 3
+ERR_BUS     = 4
+
+
+class DevmemException(Exception):
+    pass
+
+
+class Devmem:
+    """
+    The client end of a connection to devmemd.
+    """
+    def __init__(self, addr, port, verbosity=1):
+        self.remote_addr = addr
+        self.remote_port = port
+        self.verbosity = verbosity
+        self.seq = 0
+        self.connect()
+
+    def connect(self):
+        self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        if self.verbosity >= 1:
+            print("connecting to %s:%u..." % (self.remote_addr, self.remote_port))
+        self.s.connect((self.remote_addr, self.remote_port))
+        if self.verbosity >= 1:
+            print("connected to %s:%u" % (self.remote_addr, self.remote_port))
+        (status, data) = self.send_raw(REQ_NOP)
+        if status != ERR_OK:
+            print("could not establish command session with initial NOP")
+
+    def send_raw(self, code, size=0, addr=0, data=0):
+        self.seq += 1
+        seq = self.seq
+        if self.verbosity >= 2:
+            print("send seq=0x%04x req=%u size=%u addr=0x%x data=0x%x" % (seq, code, size, addr, data))
+        req = struct.pack("HBBB3xQQ", seq, 24, code, size, addr, data)
+        assert len(req) == 24
+        self.s.sendall(req)      # sendall() ensures all bytes are sent
+        rsp = self.s.recv(16)
+        if not rsp:
+            print("remote devmemd connection closed unexpectedly", file=sys.stderr)
+            raise IOError
+        if len(rsp) < 16:
+            print("recv only received %u bytes" % len(rsp))
+        (rseq, _, status, data) = struct.unpack("HBB4xQ", rsp)
+        if self.verbosity >= 2:
+            print("recv seq=0x%04x status=%d data=0x%x" % (rseq, status, data))
+        if status != ERR_OK:
+            print("status = %d" % status)
+        return (status, data)
+
+    def send(self, code, size=0, addr=0, data=0):
+        (status, data) = self.send_raw(code, size, addr, data)
+        if status != ERR_OK:
+            raise DevmemException
+        return (status, data)
+
+    def read(self, size, addr):
+        """
+        Read a value from physical memory.
+        """
+        assert size in [1,2,4,8], "bad read size: %u" % size
+        (status, data) = self.send(REQ_READ, size, addr, 0)
+        return data
+
+    def write(self, size, addr, data):
+        """
+        Write a value to physical memory.
+        """
+        assert size in [1,2,4,8], "bad write size: %u" % size
+        (status, _) = self.send(REQ_WRITE, size, addr, data)
+
+    def map(self, base, size):
+        """
+        Return an mmap-compatible object.
+        """
+        return DevmemMap(self, base, size)
+
+    def close(self):
+        self.s.close()
+
+    def __del__(self):
+        self.close()
+
+
+class DevmemMap:
+    """
+    A mmap-compatible object that redirects via Devmem.
+    """
+    def __init__(self, devmem, base, size):
+        assert isinstance(devmem, Devmem)
+        self.devmemd = devmem
+        self.map_base = base
+        self.map_size = size
+
+    def __getslice__(self, start, end):
+        size = end - start
+        assert size in [1,2,4,8], "bad read size: 0x%x..0x%x" % (start, end)
+        data = self.devmemd.read(size, self.map_base+start)
+        return struct.pack(".BH.I...Q"[size], data)
+
+    def __setslice__(self, start, end, data):
+        size = end - start
+        assert size in [1,2,4,8], "bad write size: 0x%x..0x%x" % (start, end)
+        value = struct.unpack(".BH.I...Q"[size], data)[0]
+        self.devmemd.write(size, self.map_base+start, value)
+
+
+if __name__ == "__main__":
+    import sys, argparse
+    parser = argparse.ArgumentParser(description="test client for devmemd")
+    parser.add_argument("-v", "--verbose", default=0, action="count", help="increase verbosity level")
+    parser.add_argument("target", type=str, help="target internet address and port")
+    opts = parser.parse_args()
+    (addr, port) = opts.target.split(':')
+    port = int(port)
+    m = Devmem(addr, port, verbosity=opts.verbose) 
+    while True:
+        ln = raw_input("devmem> ")
+        toks = ln.strip().split()
+        print(toks)
+        if (not toks) or toks[0].startswith('#'):
+            continue
+        req = toks[0].upper()
+        if req == 'R':
+            print("%x" % m.read(int(toks[1]), int(toks[2],16)))
+        elif req == 'W':
+            m.write(int(toks[1]), int(toks[2],16), int(toks[3],16))
+        elif req == 'Q':
+            break
+        else:
+            print("R <size> <addr>")
+            print("W <size> <addr> <data>")
+    m.close()
+

coresight-tools/devmemd/Makefile

@@ -0,0 +1,14 @@
+CCOPTS=-O2 -g -Wall -Werror -Wpedantic -Wextra -Wabi
+
+devmemd: devmemd.c devmemd.h
+	$(CC) $(CCOPTS) -o $@ $<
+
+run: devmemd
+	sudo ./devmemd
+
+strace: devmemd
+	sudo strace ./devmemd
+
+clean:
+	rm -rf devmemd
+