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![Gerd Hoffmann](/assets/img/avatar_default.png)
Setting SYSTEMTAP_TAPSET to some value other than /usr/share/systemtap/tapsets results in systemtap not finding the standard tapset library any more, which in turn breaks tracing because pid() and other standard systemtap functions are not available any more. So using SYSTEMTAP_TAPSET to point systemtap to the qemu probes will only work for the prefix=/usr installs because both qemu and system tapsets in the same directory then. All other prefixes are broken. Fix that by using the "-I $tapsetdir" command line switch instead. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-id: 20210601132414.432430-2-kraxel@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
170 lines
5.5 KiB
Python
Executable file
170 lines
5.5 KiB
Python
Executable file
#!/usr/bin/env python3
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# -*- python -*-
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#
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# Copyright (C) 2019 Red Hat, Inc
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#
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# QEMU SystemTap Trace Tool
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, see <http://www.gnu.org/licenses/>.
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import argparse
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import copy
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import os.path
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import re
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import subprocess
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import sys
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def probe_prefix(binary):
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dirname, filename = os.path.split(binary)
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return re.sub("-", ".", filename) + ".log"
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def which(binary):
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for path in os.environ["PATH"].split(os.pathsep):
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if os.path.exists(os.path.join(path, binary)):
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return os.path.join(path, binary)
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print("Unable to find '%s' in $PATH" % binary)
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sys.exit(1)
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def tapset_dir(binary):
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dirname, filename = os.path.split(binary)
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if dirname == '':
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thisfile = which(binary)
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else:
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thisfile = os.path.realpath(binary)
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if not os.path.exists(thisfile):
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print("Unable to find '%s'" % thisfile)
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sys.exit(1)
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basedir = os.path.split(thisfile)[0]
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tapset = os.path.join(basedir, "..", "share", "systemtap", "tapset")
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return os.path.realpath(tapset)
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def cmd_run(args):
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prefix = probe_prefix(args.binary)
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tapsets = tapset_dir(args.binary)
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if args.verbose:
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print("Using tapset dir '%s' for binary '%s'" % (tapsets, args.binary))
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probes = []
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for probe in args.probes:
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probes.append("probe %s.%s {}" % (prefix, probe))
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if len(probes) == 0:
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print("At least one probe pattern must be specified")
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sys.exit(1)
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script = " ".join(probes)
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if args.verbose:
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print("Compiling script '%s'" % script)
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script = """probe begin { print("Running script, <Ctrl>-c to quit\\n") } """ + script
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# We request an 8MB buffer, since the stap default 1MB buffer
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# can be easily overflowed by frequently firing QEMU traces
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stapargs = ["stap", "-s", "8", "-I", tapsets ]
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if args.pid is not None:
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stapargs.extend(["-x", args.pid])
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stapargs.extend(["-e", script])
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subprocess.call(stapargs)
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def cmd_list(args):
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tapsets = tapset_dir(args.binary)
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if args.verbose:
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print("Using tapset dir '%s' for binary '%s'" % (tapsets, args.binary))
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def print_probes(verbose, name):
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prefix = probe_prefix(args.binary)
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offset = len(prefix) + 1
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script = prefix + "." + name
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if verbose:
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print("Listing probes with name '%s'" % script)
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proc = subprocess.Popen(["stap", "-I", tapsets, "-l", script],
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stdout=subprocess.PIPE,
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universal_newlines=True)
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out, err = proc.communicate()
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if proc.returncode != 0:
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print("No probes found, are the tapsets installed in %s" % tapset_dir(args.binary))
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sys.exit(1)
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for line in out.splitlines():
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if line.startswith(prefix):
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print("%s" % line[offset:])
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if len(args.probes) == 0:
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print_probes(args.verbose, "*")
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else:
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for probe in args.probes:
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print_probes(args.verbose, probe)
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def main():
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parser = argparse.ArgumentParser(description="QEMU SystemTap trace tool")
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parser.add_argument("-v", "--verbose", help="Print verbose progress info",
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action='store_true')
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subparser = parser.add_subparsers(help="commands")
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subparser.required = True
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subparser.dest = "command"
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runparser = subparser.add_parser("run", help="Run a trace session",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog="""
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To watch all trace points on the qemu-system-x86_64 binary:
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%(argv0)s run qemu-system-x86_64
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To only watch the trace points matching the qio* and qcrypto* patterns
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%(argv0)s run qemu-system-x86_64 'qio*' 'qcrypto*'
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""" % {"argv0": sys.argv[0]})
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runparser.set_defaults(func=cmd_run)
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runparser.add_argument("--pid", "-p", dest="pid",
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help="Restrict tracing to a specific process ID")
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runparser.add_argument("binary", help="QEMU system or user emulator binary")
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runparser.add_argument("probes", help="Probe names or wildcards",
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nargs=argparse.REMAINDER)
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listparser = subparser.add_parser("list", help="List probe points",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog="""
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To list all trace points on the qemu-system-x86_64 binary:
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%(argv0)s list qemu-system-x86_64
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To only list the trace points matching the qio* and qcrypto* patterns
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%(argv0)s list qemu-system-x86_64 'qio*' 'qcrypto*'
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""" % {"argv0": sys.argv[0]})
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listparser.set_defaults(func=cmd_list)
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listparser.add_argument("binary", help="QEMU system or user emulator binary")
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listparser.add_argument("probes", help="Probe names or wildcards",
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nargs=argparse.REMAINDER)
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args = parser.parse_args()
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args.func(args)
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sys.exit(0)
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if __name__ == '__main__':
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main()
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