Viewing: page_flags.py
"""
Provide access to the page flags known by crash.
Copyright 2014 Cray Inc. All Rights Reserved
The data is gathered from the 'kmem -g' command.
"""
from pykdump.API import *
import crashlib.cid
class PageFlag:
# Note: This class should probably be abstracted somewhere as a
# bit or bitmask class, but since we don't have that yet, just
# create a new class here.
"""Represent a flag as a bit mask and a shift value."""
def __init__(self, name, shift_val):
self.name = name
self.shift = int(shift_val)
self.mask = 1 << self.shift
def __call__(self):
return self.mask
class MachPageFlags:
"""Extract the machine-specific page flags from crash.
When instantiated, this class produces an object with data members
for each kernel page flag that crash knows about, based on the kernel
version. Each page flag is an instance of class PageFlag. An example
of usage would be:
page = readSU('struct page', page_addr)
kpf = MachPageFlags()
if page.flags & kpf.PG_slab.mask:
...
"""
def __init__(self):
"""Extract the page flags from the crash 'kmem -g' command."""
for line in exec_crash_command('kmem -g').splitlines():
# crash> kmem -g
# PAGE-FLAG BIT VALUE
# PG_locked 0 0000001
# PG_waiters 1 0000002
# ...
fields = line.split()
if len(fields) < 3 or fields[0][0:3] != 'PG_': continue
name = fields[0]
shift = int(fields[1])
self.__dict__[name] = PageFlag(name, shift)
# --------------------------------------------------------------------------
# Create a shared instances of the above classes.
crashlib.cid.pgflags = MachPageFlags()
