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#
# gdb helper commands and functions for Linux kernel debugging
#
# per-cpu tools
#
# Copyright (c) Siemens AG, 2011-2013
#
# Authors:
# Jan Kiszka <jan.kiszka@siemens.com>
#
# This work is licensed under the terms of the GNU GPL version 2.
#
import gdb
from linux import tasks, utils
MAX_CPUS = 4096
def get_current_cpu():
if utils.get_gdbserver_type() == utils.GDBSERVER_QEMU:
return gdb.selected_thread().num - 1
elif utils.get_gdbserver_type() == utils.GDBSERVER_KGDB:
tid = gdb.selected_thread().ptid[2]
if tid > (0x100000000 - MAX_CPUS - 2):
return 0x100000000 - tid - 2
else:
return tasks.get_thread_info(tasks.get_task_by_pid(tid))['cpu']
else:
raise gdb.GdbError("Sorry, obtaining the current CPU is not yet "
"supported with this gdb server.")
def per_cpu(var_ptr, cpu):
if cpu == -1:
cpu = get_current_cpu()
if utils.is_target_arch("sparc:v9"):
offset = gdb.parse_and_eval(
"trap_block[{0}].__per_cpu_base".format(str(cpu)))
else:
try:
offset = gdb.parse_and_eval(
"__per_cpu_offset[{0}]".format(str(cpu)))
except gdb.error:
# !CONFIG_SMP case
offset = 0
pointer = var_ptr.cast(utils.get_long_type()) + offset
return pointer.cast(var_ptr.type).dereference()
cpu_mask = {}
def cpu_mask_invalidate(event):
global cpu_mask
cpu_mask = {}
gdb.events.stop.disconnect(cpu_mask_invalidate)
if hasattr(gdb.events, 'new_objfile'):
gdb.events.new_objfile.disconnect(cpu_mask_invalidate)
def cpu_list(mask_name):
global cpu_mask
mask = None
if mask_name in cpu_mask:
mask = cpu_mask[mask_name]
if mask is None:
mask = gdb.parse_and_eval(mask_name + ".bits")
if hasattr(gdb, 'events'):
cpu_mask[mask_name] = mask
gdb.events.stop.connect(cpu_mask_invalidate)
if hasattr(gdb.events, 'new_objfile'):
gdb.events.new_objfile.connect(cpu_mask_invalidate)
bits_per_entry = mask[0].type.sizeof * 8
num_entries = mask.type.sizeof * 8 / bits_per_entry
entry = -1
bits = 0
while True:
while bits == 0:
entry += 1
if entry == num_entries:
return
bits = mask[entry]
if bits != 0:
bit = 0
break
while bits & 1 == 0:
bits >>= 1
bit += 1
cpu = entry * bits_per_entry + bit
bits >>= 1
bit += 1
yield int(cpu)
def each_online_cpu():
for cpu in cpu_list("__cpu_online_mask"):
yield cpu
def each_present_cpu():
for cpu in cpu_list("__cpu_present_mask"):
yield cpu
def each_possible_cpu():
for cpu in cpu_list("__cpu_possible_mask"):
yield cpu
def each_active_cpu():
for cpu in cpu_list("__cpu_active_mask"):
yield cpu
class LxCpus(gdb.Command):
"""List CPU status arrays
Displays the known state of each CPU based on the kernel masks
and can help identify the state of hotplugged CPUs"""
def __init__(self):
super(LxCpus, self).__init__("lx-cpus", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
gdb.write("Possible CPUs : {}\n".format(list(each_possible_cpu())))
gdb.write("Present CPUs : {}\n".format(list(each_present_cpu())))
gdb.write("Online CPUs : {}\n".format(list(each_online_cpu())))
gdb.write("Active CPUs : {}\n".format(list(each_active_cpu())))
LxCpus()
class PerCpu(gdb.Function):
"""Return per-cpu variable.
$lx_per_cpu("VAR"[, CPU]): Return the per-cpu variable called VAR for the
given CPU number. If CPU is omitted, the CPU of the current context is used.
Note that VAR has to be quoted as string."""
def __init__(self):
super(PerCpu, self).__init__("lx_per_cpu")
def invoke(self, var_name, cpu=-1):
var_ptr = gdb.parse_and_eval("&" + var_name.string())
return per_cpu(var_ptr, cpu)
PerCpu()
class LxCurrentFunc(gdb.Function):
"""Return current task.
$lx_current([CPU]): Return the per-cpu task variable for the given CPU
number. If CPU is omitted, the CPU of the current context is used."""
def __init__(self):
super(LxCurrentFunc, self).__init__("lx_current")
def invoke(self, cpu=-1):
var_ptr = gdb.parse_and_eval("¤t_task")
return per_cpu(var_ptr, cpu).dereference()
LxCurrentFunc()
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