219 lines
9.0 KiB
Python
219 lines
9.0 KiB
Python
# Copyright 2016 Sasha Goldshtein
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import print_function
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import ctypes as ct
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import sys
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from .libbcc import lib, _USDT_CB, _USDT_PROBE_CB, \
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bcc_usdt_location, bcc_usdt_argument, \
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BCC_USDT_ARGUMENT_FLAGS
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class USDTException(Exception):
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pass
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class USDTProbeArgument(object):
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def __init__(self, argument):
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self.signed = argument.size < 0
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self.size = abs(argument.size)
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self.valid = argument.valid
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.CONSTANT != 0:
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self.constant = argument.constant
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_OFFSET != 0:
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self.deref_offset = argument.deref_offset
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_IDENT != 0:
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self.deref_ident = argument.deref_ident
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.BASE_REGISTER_NAME != 0:
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self.base_register_name = argument.base_register_name
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.INDEX_REGISTER_NAME != 0:
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self.index_register_name = argument.index_register_name
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.SCALE != 0:
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self.scale = argument.scale
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def _size_prefix(self):
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return "%d %s bytes" % \
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(self.size, "signed " if self.signed else "unsigned")
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def _format(self):
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# This mimics the logic in cc/usdt_args.cc that gives meaning to the
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# various argument settings. A change there will require a change here.
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.CONSTANT != 0:
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return "%d" % self.constant
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_OFFSET == 0:
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return "%s" % self.base_register_name.decode()
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_OFFSET != 0 and \
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self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_IDENT == 0:
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.INDEX_REGISTER_NAME != 0:
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index_offset = " + %s" % self.index_register_name.decode()
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.SCALE != 0:
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index_offset += " * %d" % self.scale
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else:
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index_offset = ""
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sign = '+' if self.deref_offset >= 0 else '-'
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return "*(%s %s %d%s)" % (self.base_register_name.decode(),
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sign, abs(self.deref_offset), index_offset)
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if self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_OFFSET != 0 and \
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self.valid & BCC_USDT_ARGUMENT_FLAGS.DEREF_IDENT != 0 and \
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self.valid & BCC_USDT_ARGUMENT_FLAGS.BASE_REGISTER_NAME != 0 and \
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self.base_register_name == "ip":
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sign = '+' if self.deref_offset >= 0 else '-'
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return "*(&%s %s %d)" % (self.deref_ident.decode(),
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sign, abs(self.deref_offset))
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# If we got here, this is an unrecognized case. Doesn't mean it's
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# necessarily bad, so just provide the raw data. It just means that
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# other tools won't be able to work with this argument.
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return "unrecognized argument format, flags %d" % self.valid
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def __str__(self):
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return "%s @ %s" % (self._size_prefix(), self._format())
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class USDTProbeLocation(object):
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def __init__(self, probe, index, location):
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self.probe = probe
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self.index = index
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self.num_arguments = probe.num_arguments
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self.address = location.address
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self.bin_path = location.bin_path
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def __str__(self):
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return "%s 0x%x" % (self.bin_path.decode(), self.address)
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def get_argument(self, index):
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arg = bcc_usdt_argument()
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res = lib.bcc_usdt_get_argument(self.probe.context, self.probe.provider,
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self.probe.name,
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self.index, index, ct.byref(arg))
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if res != 0:
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raise USDTException(
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"error retrieving probe argument %d location %d" %
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(index, self.index))
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return USDTProbeArgument(arg)
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class USDTProbe(object):
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def __init__(self, context, probe):
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self.context = context
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self.provider = probe.provider
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self.name = probe.name
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self.bin_path = probe.bin_path
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self.semaphore = probe.semaphore
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self.num_locations = probe.num_locations
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self.num_arguments = probe.num_arguments
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def __str__(self):
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return "%s:%s [sema 0x%x]" % \
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(self.provider.decode(), self.name.decode(), self.semaphore)
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def short_name(self):
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return "%s:%s" % (self.provider.decode(), self.name.decode())
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def get_location(self, index):
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loc = bcc_usdt_location()
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res = lib.bcc_usdt_get_location(self.context, self.provider, self.name,
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index, ct.byref(loc))
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if res != 0:
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raise USDTException("error retrieving probe location %d" % index)
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return USDTProbeLocation(self, index, loc)
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class USDT(object):
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def __init__(self, pid=None, path=None):
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if pid and pid != -1:
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self.pid = pid
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if path:
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self.context = lib.bcc_usdt_new_frompid(pid, path.encode('ascii'))
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else:
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self.context = lib.bcc_usdt_new_frompid(pid, ct.c_char_p(0))
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if self.context == None:
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raise USDTException("USDT failed to instrument PID %d" % pid)
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elif path:
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self.path = path
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self.context = lib.bcc_usdt_new_frompath(path.encode('ascii'))
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if self.context == None:
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raise USDTException("USDT failed to instrument path %s" % path)
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else:
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raise USDTException(
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"either a pid or a binary path must be specified")
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def __del__(self):
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lib.bcc_usdt_close(self.context)
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def enable_probe(self, probe, fn_name):
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probe_parts = probe.split(":", 1)
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if len(probe_parts) == 1:
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ret = lib.bcc_usdt_enable_probe(
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self.context, probe.encode('ascii'), fn_name.encode('ascii'))
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else:
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(provider_name, probe_name) = probe_parts
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ret = lib.bcc_usdt_enable_fully_specified_probe(
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self.context, provider_name.encode('ascii'), probe_name.encode('ascii'),
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fn_name.encode('ascii'))
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if ret != 0:
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raise USDTException(
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"""Failed to enable USDT probe '%s':
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the specified pid might not contain the given language's runtime,
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or the runtime was not built with the required USDT probes. Look
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for a configure flag similar to --with-dtrace or --enable-dtrace.
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To check which probes are present in the process, use the tplist tool.
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""" % probe)
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def enable_probe_or_bail(self, probe, fn_name):
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try:
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self.enable_probe(probe, fn_name)
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except USDTException as e:
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print(e, file=sys.stderr)
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sys.exit(1)
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def get_context(self):
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return self.context
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def get_text(self):
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ctx_array = (ct.c_void_p * 1)()
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ctx_array[0] = ct.c_void_p(self.context)
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return lib.bcc_usdt_genargs(ctx_array, 1).decode()
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def get_probe_arg_ctype(self, probe_name, arg_index):
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probe_parts = probe_name.split(":", 1)
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if len(probe_parts) == 1:
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return lib.bcc_usdt_get_probe_argctype(
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self.context, probe_name.encode('ascii'), arg_index).decode()
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else:
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(provider_name, probe) = probe_parts
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return lib.bcc_usdt_get_fully_specified_probe_argctype(
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self.context, provider_name.encode('ascii'), probe.encode('ascii'), arg_index).decode()
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def enumerate_probes(self):
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probes = []
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def _add_probe(probe):
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probes.append(USDTProbe(self.context, probe.contents))
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lib.bcc_usdt_foreach(self.context, _USDT_CB(_add_probe))
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return probes
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# This is called by the BPF module's __init__ when it realizes that there
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# is a USDT context and probes need to be attached.
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def attach_uprobes(self, bpf, attach_usdt_ignore_pid):
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probes = self.enumerate_active_probes()
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for (binpath, fn_name, addr, pid) in probes:
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if attach_usdt_ignore_pid:
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pid = -1
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bpf.attach_uprobe(name=binpath, fn_name=fn_name,
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addr=addr, pid=pid)
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def enumerate_active_probes(self):
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probes = []
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def _add_probe(binpath, fn_name, addr, pid):
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probes.append((binpath, fn_name, addr, pid))
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lib.bcc_usdt_foreach_uprobe(self.context, _USDT_PROBE_CB(_add_probe))
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return probes
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