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#
# gdb helper commands and functions for Linux kernel debugging
#
# Kernel proc information reader
#
# Copyright (c) 2016 Linaro Ltd
#
# Authors:
# Kieran Bingham <[email protected]>
#
# This work is licensed under the terms of the GNU GPL version 2.
#
import gdb
from linux import constants
from linux import utils
from linux import tasks
from linux import lists
from struct import *
class LxCmdLine(gdb.Command):
""" Report the Linux Commandline used in the current kernel.
Equivalent to cat /proc/cmdline on a running target"""
def __init__(self):
super(LxCmdLine, self).__init__("lx-cmdline", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
gdb.write(gdb.parse_and_eval("saved_command_line").string() + "\n")
LxCmdLine()
class LxVersion(gdb.Command):
""" Report the Linux Version of the current kernel.
Equivalent to cat /proc/version on a running target"""
def __init__(self):
super(LxVersion, self).__init__("lx-version", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
# linux_banner should contain a newline
gdb.write(gdb.parse_and_eval("(char *)linux_banner").string())
LxVersion()
# Resource Structure Printers
# /proc/iomem
# /proc/ioports
def get_resources(resource, depth):
while resource:
yield resource, depth
child = resource['child']
if child:
for res, deep in get_resources(child, depth + 1):
yield res, deep
resource = resource['sibling']
def show_lx_resources(resource_str):
resource = gdb.parse_and_eval(resource_str)
width = 4 if resource['end'] < 0x10000 else 8
# Iterate straight to the first child
for res, depth in get_resources(resource['child'], 0):
start = int(res['start'])
end = int(res['end'])
gdb.write(" " * depth * 2 +
"{0:0{1}x}-".format(start, width) +
"{0:0{1}x} : ".format(end, width) +
res['name'].string() + "\n")
class LxIOMem(gdb.Command):
"""Identify the IO memory resource locations defined by the kernel
Equivalent to cat /proc/iomem on a running target"""
def __init__(self):
super(LxIOMem, self).__init__("lx-iomem", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
return show_lx_resources("iomem_resource")
LxIOMem()
class LxIOPorts(gdb.Command):
"""Identify the IO port resource locations defined by the kernel
Equivalent to cat /proc/ioports on a running target"""
def __init__(self):
super(LxIOPorts, self).__init__("lx-ioports", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
return show_lx_resources("ioport_resource")
LxIOPorts()
# Mount namespace viewer
# /proc/mounts
def info_opts(lst, opt):
opts = ""
for key, string in lst.items():
if opt & key:
opts += string
return opts
FS_INFO = {constants.LX_SB_SYNCHRONOUS: ",sync",
constants.LX_SB_MANDLOCK: ",mand",
constants.LX_SB_DIRSYNC: ",dirsync",
constants.LX_SB_NOATIME: ",noatime",
constants.LX_SB_NODIRATIME: ",nodiratime"}
MNT_INFO = {constants.LX_MNT_NOSUID: ",nosuid",
constants.LX_MNT_NODEV: ",nodev",
constants.LX_MNT_NOEXEC: ",noexec",
constants.LX_MNT_NOATIME: ",noatime",
constants.LX_MNT_NODIRATIME: ",nodiratime",
constants.LX_MNT_RELATIME: ",relatime"}
mount_type = utils.CachedType("struct mount")
mount_ptr_type = mount_type.get_type().pointer()
class LxMounts(gdb.Command):
"""Report the VFS mounts of the current process namespace.
Equivalent to cat /proc/mounts on a running target
An integer value can be supplied to display the mount
values of that process namespace"""
def __init__(self):
super(LxMounts, self).__init__("lx-mounts", gdb.COMMAND_DATA)
# Equivalent to proc_namespace.c:show_vfsmnt
# However, that has the ability to call into s_op functions
# whereas we cannot and must make do with the information we can obtain.
def invoke(self, arg, from_tty):
argv = gdb.string_to_argv(arg)
if len(argv) >= 1:
try:
pid = int(argv[0])
except gdb.error:
raise gdb.GdbError("Provide a PID as integer value")
else:
pid = 1
task = tasks.get_task_by_pid(pid)
if not task:
raise gdb.GdbError("Couldn't find a process with PID {}"
.format(pid))
namespace = task['nsproxy']['mnt_ns']
if not namespace:
raise gdb.GdbError("No namespace for current process")
gdb.write("{:^18} {:^15} {:>9} {} {} options\n".format(
"mount", "super_block", "devname", "pathname", "fstype"))
for vfs in lists.list_for_each_entry(namespace['list'],
mount_ptr_type, "mnt_list"):
devname = vfs['mnt_devname'].string()
devname = devname if devname else "none"
pathname = ""
parent = vfs
while True:
mntpoint = parent['mnt_mountpoint']
pathname = utils.dentry_name(mntpoint) + pathname
if (parent == parent['mnt_parent']):
break
parent = parent['mnt_parent']
if (pathname == ""):
pathname = "/"
superblock = vfs['mnt']['mnt_sb']
fstype = superblock['s_type']['name'].string()
s_flags = int(superblock['s_flags'])
m_flags = int(vfs['mnt']['mnt_flags'])
rd = "ro" if (s_flags & constants.LX_SB_RDONLY) else "rw"
gdb.write("{} {} {} {} {} {}{}{} 0 0\n".format(
vfs.format_string(), superblock.format_string(), devname,
pathname, fstype, rd, info_opts(FS_INFO, s_flags),
info_opts(MNT_INFO, m_flags)))
LxMounts()
class LxFdtDump(gdb.Command):
"""Output Flattened Device Tree header and dump FDT blob to the filename
specified as the command argument. Equivalent to
'cat /proc/fdt > fdtdump.dtb' on a running target"""
def __init__(self):
super(LxFdtDump, self).__init__("lx-fdtdump", gdb.COMMAND_DATA,
gdb.COMPLETE_FILENAME)
def fdthdr_to_cpu(self, fdt_header):
fdt_header_be = ">IIIIIII"
fdt_header_le = "<IIIIIII"
if utils.get_target_endianness() == 1:
output_fmt = fdt_header_le
else:
output_fmt = fdt_header_be
return unpack(output_fmt, pack(fdt_header_be,
fdt_header['magic'],
fdt_header['totalsize'],
fdt_header['off_dt_struct'],
fdt_header['off_dt_strings'],
fdt_header['off_mem_rsvmap'],
fdt_header['version'],
fdt_header['last_comp_version']))
def invoke(self, arg, from_tty):
if not constants.LX_CONFIG_OF:
raise gdb.GdbError("Kernel not compiled with CONFIG_OF\n")
if len(arg) == 0:
filename = "fdtdump.dtb"
else:
filename = arg
py_fdt_header_ptr = gdb.parse_and_eval(
"(const struct fdt_header *) initial_boot_params")
py_fdt_header = py_fdt_header_ptr.dereference()
fdt_header = self.fdthdr_to_cpu(py_fdt_header)
if fdt_header[0] != constants.LX_OF_DT_HEADER:
raise gdb.GdbError("No flattened device tree magic found\n")
gdb.write("fdt_magic: 0x{:02X}\n".format(fdt_header[0]))
gdb.write("fdt_totalsize: 0x{:02X}\n".format(fdt_header[1]))
gdb.write("off_dt_struct: 0x{:02X}\n".format(fdt_header[2]))
gdb.write("off_dt_strings: 0x{:02X}\n".format(fdt_header[3]))
gdb.write("off_mem_rsvmap: 0x{:02X}\n".format(fdt_header[4]))
gdb.write("version: {}\n".format(fdt_header[5]))
gdb.write("last_comp_version: {}\n".format(fdt_header[6]))
inf = gdb.inferiors()[0]
fdt_buf = utils.read_memoryview(inf, py_fdt_header_ptr,
fdt_header[1]).tobytes()
try:
f = open(filename, 'wb')
except gdb.error:
raise gdb.GdbError("Could not open file to dump fdt")
f.write(fdt_buf)
f.close()
gdb.write("Dumped fdt blob to " + filename + "\n")
LxFdtDump()
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