xemu/scripts/tracetool/__init__.py
Daniel P. Berrangé 772f1b3721 trace: forbid use of %m in trace event format strings
The '%m' format instructs glibc's printf()/syslog() implementation to
insert the contents of strerror(errno). Since this is a glibc extension
it should generally be avoided in QEMU due to need for portability to a
variety of platforms.

Even though vfio is Linux-only code that could otherwise use "%m", it
must still be avoided in trace-events files because several of the
backends do not use the format string and so this error information is
invisible to them.

The errno string value should be given as an explicit trace argument
instead, making it accessible to all backends. This also allows it to
work correctly with future patches that use the format string with
systemtap's simple printf code.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20190123120016.4538-4-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2019-01-24 14:16:56 +00:00

473 lines
14 KiB
Python

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Machinery for generating tracing-related intermediate files.
"""
__author__ = "Lluís Vilanova <vilanova@ac.upc.edu>"
__copyright__ = "Copyright 2012-2017, Lluís Vilanova <vilanova@ac.upc.edu>"
__license__ = "GPL version 2 or (at your option) any later version"
__maintainer__ = "Stefan Hajnoczi"
__email__ = "stefanha@linux.vnet.ibm.com"
import re
import sys
import weakref
import tracetool.format
import tracetool.backend
import tracetool.transform
def error_write(*lines):
"""Write a set of error lines."""
sys.stderr.writelines("\n".join(lines) + "\n")
def error(*lines):
"""Write a set of error lines and exit."""
error_write(*lines)
sys.exit(1)
def out(*lines, **kwargs):
"""Write a set of output lines.
You can use kwargs as a shorthand for mapping variables when formating all
the strings in lines.
"""
lines = [ l % kwargs for l in lines ]
sys.stdout.writelines("\n".join(lines) + "\n")
# We only want to allow standard C types or fixed sized
# integer types. We don't want QEMU specific types
# as we can't assume trace backends can resolve all the
# typedefs
ALLOWED_TYPES = [
"int",
"long",
"short",
"char",
"bool",
"unsigned",
"signed",
"int8_t",
"uint8_t",
"int16_t",
"uint16_t",
"int32_t",
"uint32_t",
"int64_t",
"uint64_t",
"void",
"size_t",
"ssize_t",
"uintptr_t",
"ptrdiff_t",
# Magic substitution is done by tracetool
"TCGv",
]
def validate_type(name):
bits = name.split(" ")
for bit in bits:
bit = re.sub("\*", "", bit)
if bit == "":
continue
if bit == "const":
continue
if bit not in ALLOWED_TYPES:
raise ValueError("Argument type '%s' is not in whitelist. "
"Only standard C types and fixed size integer "
"types should be used. struct, union, and "
"other complex pointer types should be "
"declared as 'void *'" % name)
class Arguments:
"""Event arguments description."""
def __init__(self, args):
"""
Parameters
----------
args :
List of (type, name) tuples or Arguments objects.
"""
self._args = []
for arg in args:
if isinstance(arg, Arguments):
self._args.extend(arg._args)
else:
self._args.append(arg)
def copy(self):
"""Create a new copy."""
return Arguments(list(self._args))
@staticmethod
def build(arg_str):
"""Build and Arguments instance from an argument string.
Parameters
----------
arg_str : str
String describing the event arguments.
"""
res = []
for arg in arg_str.split(","):
arg = arg.strip()
if not arg:
raise ValueError("Empty argument (did you forget to use 'void'?)")
if arg == 'void':
continue
if '*' in arg:
arg_type, identifier = arg.rsplit('*', 1)
arg_type += '*'
identifier = identifier.strip()
else:
arg_type, identifier = arg.rsplit(None, 1)
validate_type(arg_type)
res.append((arg_type, identifier))
return Arguments(res)
def __getitem__(self, index):
if isinstance(index, slice):
return Arguments(self._args[index])
else:
return self._args[index]
def __iter__(self):
"""Iterate over the (type, name) pairs."""
return iter(self._args)
def __len__(self):
"""Number of arguments."""
return len(self._args)
def __str__(self):
"""String suitable for declaring function arguments."""
if len(self._args) == 0:
return "void"
else:
return ", ".join([ " ".join([t, n]) for t,n in self._args ])
def __repr__(self):
"""Evaluable string representation for this object."""
return "Arguments(\"%s\")" % str(self)
def names(self):
"""List of argument names."""
return [ name for _, name in self._args ]
def types(self):
"""List of argument types."""
return [ type_ for type_, _ in self._args ]
def casted(self):
"""List of argument names casted to their type."""
return ["(%s)%s" % (type_, name) for type_, name in self._args]
def transform(self, *trans):
"""Return a new Arguments instance with transformed types.
The types in the resulting Arguments instance are transformed according
to tracetool.transform.transform_type.
"""
res = []
for type_, name in self._args:
res.append((tracetool.transform.transform_type(type_, *trans),
name))
return Arguments(res)
class Event(object):
"""Event description.
Attributes
----------
name : str
The event name.
fmt : str
The event format string.
properties : set(str)
Properties of the event.
args : Arguments
The event arguments.
"""
_CRE = re.compile("((?P<props>[\w\s]+)\s+)?"
"(?P<name>\w+)"
"\((?P<args>[^)]*)\)"
"\s*"
"(?:(?:(?P<fmt_trans>\".+),)?\s*(?P<fmt>\".+))?"
"\s*")
_VALID_PROPS = set(["disable", "tcg", "tcg-trans", "tcg-exec", "vcpu"])
def __init__(self, name, props, fmt, args, orig=None,
event_trans=None, event_exec=None):
"""
Parameters
----------
name : string
Event name.
props : list of str
Property names.
fmt : str, list of str
Event printing format string(s).
args : Arguments
Event arguments.
orig : Event or None
Original Event before transformation/generation.
event_trans : Event or None
Generated translation-time event ("tcg" property).
event_exec : Event or None
Generated execution-time event ("tcg" property).
"""
self.name = name
self.properties = props
self.fmt = fmt
self.args = args
self.event_trans = event_trans
self.event_exec = event_exec
if len(args) > 10:
raise ValueError("Event '%s' has more than maximum permitted "
"argument count" % name)
if orig is None:
self.original = weakref.ref(self)
else:
self.original = orig
unknown_props = set(self.properties) - self._VALID_PROPS
if len(unknown_props) > 0:
raise ValueError("Unknown properties: %s"
% ", ".join(unknown_props))
assert isinstance(self.fmt, str) or len(self.fmt) == 2
def copy(self):
"""Create a new copy."""
return Event(self.name, list(self.properties), self.fmt,
self.args.copy(), self, self.event_trans, self.event_exec)
@staticmethod
def build(line_str):
"""Build an Event instance from a string.
Parameters
----------
line_str : str
Line describing the event.
"""
m = Event._CRE.match(line_str)
assert m is not None
groups = m.groupdict('')
name = groups["name"]
props = groups["props"].split()
fmt = groups["fmt"]
fmt_trans = groups["fmt_trans"]
if fmt.find("%m") != -1 or fmt_trans.find("%m") != -1:
raise ValueError("Event format '%m' is forbidden, pass the error "
"as an explicit trace argument")
if len(fmt_trans) > 0:
fmt = [fmt_trans, fmt]
args = Arguments.build(groups["args"])
if "tcg-trans" in props:
raise ValueError("Invalid property 'tcg-trans'")
if "tcg-exec" in props:
raise ValueError("Invalid property 'tcg-exec'")
if "tcg" not in props and not isinstance(fmt, str):
raise ValueError("Only events with 'tcg' property can have two format strings")
if "tcg" in props and isinstance(fmt, str):
raise ValueError("Events with 'tcg' property must have two format strings")
event = Event(name, props, fmt, args)
# add implicit arguments when using the 'vcpu' property
import tracetool.vcpu
event = tracetool.vcpu.transform_event(event)
return event
def __repr__(self):
"""Evaluable string representation for this object."""
if isinstance(self.fmt, str):
fmt = self.fmt
else:
fmt = "%s, %s" % (self.fmt[0], self.fmt[1])
return "Event('%s %s(%s) %s')" % (" ".join(self.properties),
self.name,
self.args,
fmt)
# Star matching on PRI is dangerous as one might have multiple
# arguments with that format, hence the non-greedy version of it.
_FMT = re.compile("(%[\d\.]*\w+|%.*?PRI\S+)")
def formats(self):
"""List conversion specifiers in the argument print format string."""
assert not isinstance(self.fmt, list)
return self._FMT.findall(self.fmt)
QEMU_TRACE = "trace_%(name)s"
QEMU_TRACE_NOCHECK = "_nocheck__" + QEMU_TRACE
QEMU_TRACE_TCG = QEMU_TRACE + "_tcg"
QEMU_DSTATE = "_TRACE_%(NAME)s_DSTATE"
QEMU_BACKEND_DSTATE = "TRACE_%(NAME)s_BACKEND_DSTATE"
QEMU_EVENT = "_TRACE_%(NAME)s_EVENT"
def api(self, fmt=None):
if fmt is None:
fmt = Event.QEMU_TRACE
return fmt % {"name": self.name, "NAME": self.name.upper()}
def transform(self, *trans):
"""Return a new Event with transformed Arguments."""
return Event(self.name,
list(self.properties),
self.fmt,
self.args.transform(*trans),
self)
def read_events(fobj, fname):
"""Generate the output for the given (format, backends) pair.
Parameters
----------
fobj : file
Event description file.
fname : str
Name of event file
Returns a list of Event objects
"""
events = []
for lineno, line in enumerate(fobj, 1):
if line[-1] != '\n':
raise ValueError("%s does not end with a new line" % fname)
if not line.strip():
continue
if line.lstrip().startswith('#'):
continue
try:
event = Event.build(line)
except ValueError as e:
arg0 = 'Error at %s:%d: %s' % (fname, lineno, e.args[0])
e.args = (arg0,) + e.args[1:]
raise
# transform TCG-enabled events
if "tcg" not in event.properties:
events.append(event)
else:
event_trans = event.copy()
event_trans.name += "_trans"
event_trans.properties += ["tcg-trans"]
event_trans.fmt = event.fmt[0]
# ignore TCG arguments
args_trans = []
for atrans, aorig in zip(
event_trans.transform(tracetool.transform.TCG_2_HOST).args,
event.args):
if atrans == aorig:
args_trans.append(atrans)
event_trans.args = Arguments(args_trans)
event_exec = event.copy()
event_exec.name += "_exec"
event_exec.properties += ["tcg-exec"]
event_exec.fmt = event.fmt[1]
event_exec.args = event_exec.args.transform(tracetool.transform.TCG_2_HOST)
new_event = [event_trans, event_exec]
event.event_trans, event.event_exec = new_event
events.extend(new_event)
return events
class TracetoolError (Exception):
"""Exception for calls to generate."""
pass
def try_import(mod_name, attr_name=None, attr_default=None):
"""Try to import a module and get an attribute from it.
Parameters
----------
mod_name : str
Module name.
attr_name : str, optional
Name of an attribute in the module.
attr_default : optional
Default value if the attribute does not exist in the module.
Returns
-------
A pair indicating whether the module could be imported and the module or
object or attribute value.
"""
try:
module = __import__(mod_name, globals(), locals(), ["__package__"])
if attr_name is None:
return True, module
return True, getattr(module, str(attr_name), attr_default)
except ImportError:
return False, None
def generate(events, group, format, backends,
binary=None, probe_prefix=None):
"""Generate the output for the given (format, backends) pair.
Parameters
----------
events : list
list of Event objects to generate for
group: str
Name of the tracing group
format : str
Output format name.
backends : list
Output backend names.
binary : str or None
See tracetool.backend.dtrace.BINARY.
probe_prefix : str or None
See tracetool.backend.dtrace.PROBEPREFIX.
"""
# fix strange python error (UnboundLocalError tracetool)
import tracetool
format = str(format)
if len(format) is 0:
raise TracetoolError("format not set")
if not tracetool.format.exists(format):
raise TracetoolError("unknown format: %s" % format)
if len(backends) is 0:
raise TracetoolError("no backends specified")
for backend in backends:
if not tracetool.backend.exists(backend):
raise TracetoolError("unknown backend: %s" % backend)
backend = tracetool.backend.Wrapper(backends, format)
import tracetool.backend.dtrace
tracetool.backend.dtrace.BINARY = binary
tracetool.backend.dtrace.PROBEPREFIX = probe_prefix
tracetool.format.generate(events, format, backend, group)