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scripts/gdb: add mount point list command
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lx-mounts will identify current mount points based on the 'init_task'
namespace by default, as we do not yet have a kernel thread list
implementation to select the current running thread.

Optionally, a user can specify a PID to list from that process'
namespace

Link: http://lkml.kernel.org/r/e614c7bc32d2350b4ff1627ec761a7148e65bfe6.1462865983.git.jan.kiszka@siemens.com
Signed-off-by: Kieran Bingham <kieran.bingham@linaro.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kieran Bingham authored and Linus Torvalds committed May 24, 2016
1 parent e7165a2 commit c1a1539
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20 changes: 20 additions & 0 deletions scripts/gdb/linux/constants.py.in
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,11 @@
*
*/

#include <linux/fs.h>
#include <linux/mount.h>

/* We need to stringify expanded macros so that they can be parsed */

#define STRING(x) #x
#define XSTRING(x) STRING(x)

Expand All @@ -30,3 +34,19 @@
<!-- end-c-headers -->

import gdb

/* linux/fs.h */
LX_VALUE(MS_RDONLY)
LX_VALUE(MS_SYNCHRONOUS)
LX_VALUE(MS_MANDLOCK)
LX_VALUE(MS_DIRSYNC)
LX_VALUE(MS_NOATIME)
LX_VALUE(MS_NODIRATIME)

/* linux/mount.h */
LX_VALUE(MNT_NOSUID)
LX_VALUE(MNT_NODEV)
LX_VALUE(MNT_NOEXEC)
LX_VALUE(MNT_NOATIME)
LX_VALUE(MNT_NODIRATIME)
LX_VALUE(MNT_RELATIME)
99 changes: 99 additions & 0 deletions scripts/gdb/linux/proc.py
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,10 @@
#

import gdb
from linux import constants
from linux import utils
from linux import tasks
from linux import lists


class LxCmdLine(gdb.Command):
Expand Down Expand Up @@ -96,3 +100,98 @@ 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_MS_SYNCHRONOUS: ",sync",
constants.LX_MS_MANDLOCK: ",mand",
constants.LX_MS_DIRSYNC: ",dirsync",
constants.LX_MS_NOATIME: ",noatime",
constants.LX_MS_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:
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")

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_MS_RDONLY) else "rw"

gdb.write(
"{} {} {} {}{}{} 0 0\n"
.format(devname,
pathname,
fstype,
rd,
info_opts(FS_INFO, s_flags),
info_opts(MNT_INFO, m_flags)))

LxMounts()

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