Merge remote-tracking branch 'remotes/stefanha/tags/tracing-pull-request' into staging

Pull request

User-visible changes:
 * The new qemu-trace-stap script makes it convenient to collect traces without
   writing SystemTap scripts.  See "man qemu-trace-stap" for details.

# gpg: Signature made Wed 30 Jan 2019 03:17:57 GMT
# gpg:                using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/tracing-pull-request:
  trace: rerun tracetool after ./configure changes
  trace: improve runstate tracing
  trace: add ability to do simple printf logging via systemtap
  trace: forbid use of %m in trace event format strings
  trace: enforce that every trace-events file has a final newline
  display: ensure qxl log_buf is a nul terminated string

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/scripts/qemu-trace-stap b/scripts/qemu-trace-stap
new file mode 100755
index 0000000000..91d1051cdc
--- /dev/null
+++ b/scripts/qemu-trace-stap
@@ -0,0 +1,175 @@
+#!/usr/bin/python
+# -*- python -*-
+#
+# Copyright (C) 2019 Red Hat, Inc
+#
+# QEMU SystemTap Trace Tool
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+from __future__ import print_function
+
+import argparse
+import copy
+import os.path
+import re
+import subprocess
+import sys
+
+
+def probe_prefix(binary):
+    dirname, filename = os.path.split(binary)
+    return re.sub("-", ".", filename) + ".log"
+
+
+def which(binary):
+    for path in os.environ["PATH"].split(os.pathsep):
+        if os.path.exists(os.path.join(path, binary)):
+                return os.path.join(path, binary)
+
+    print("Unable to find '%s' in $PATH" % binary)
+    sys.exit(1)
+
+
+def tapset_dir(binary):
+    dirname, filename = os.path.split(binary)
+    if dirname == '':
+        thisfile = which(binary)
+    else:
+        thisfile = os.path.realpath(binary)
+        if not os.path.exists(thisfile):
+            print("Unable to find '%s'" % thisfile)
+            sys.exit(1)
+
+    basedir = os.path.split(thisfile)[0]
+    tapset = os.path.join(basedir, "..", "share", "systemtap", "tapset")
+    return os.path.realpath(tapset)
+
+
+def tapset_env(tapset_dir):
+    tenv = copy.copy(os.environ)
+    tenv["SYSTEMTAP_TAPSET"] = tapset_dir
+    return tenv
+
+def cmd_run(args):
+    prefix = probe_prefix(args.binary)
+    tapsets = tapset_dir(args.binary)
+
+    if args.verbose:
+        print("Using tapset dir '%s' for binary '%s'" % (tapsets, args.binary))
+
+    probes = []
+    for probe in args.probes:
+        probes.append("probe %s.%s {}" % (prefix, probe))
+    if len(probes) == 0:
+        print("At least one probe pattern must be specified")
+        sys.exit(1)
+
+    script = " ".join(probes)
+    if args.verbose:
+        print("Compiling script '%s'" % script)
+        script = """probe begin { print("Running script, <Ctrl>-c to quit\\n") } """ + script
+
+    # We request an 8MB buffer, since the stap default 1MB buffer
+    # can be easily overflowed by frequently firing QEMU traces
+    stapargs = ["stap", "-s", "8"]
+    if args.pid is not None:
+        stapargs.extend(["-x", args.pid])
+    stapargs.extend(["-e", script])
+    subprocess.call(stapargs, env=tapset_env(tapsets))
+
+
+def cmd_list(args):
+    tapsets = tapset_dir(args.binary)
+
+    if args.verbose:
+        print("Using tapset dir '%s' for binary '%s'" % (tapsets, args.binary))
+
+    def print_probes(verbose, name):
+        prefix = probe_prefix(args.binary)
+        offset = len(prefix) + 1
+        script = prefix + "." + name
+
+        if verbose:
+            print("Listing probes with name '%s'" % script)
+        proc = subprocess.Popen(["stap", "-l", script],
+                                stdout=subprocess.PIPE, env=tapset_env(tapsets))
+        out, err = proc.communicate()
+        if proc.returncode != 0:
+            print("No probes found, are the tapsets installed in %s" % tapset_dir(args.binary))
+            sys.exit(1)
+
+        for line in out.splitlines():
+            if line.startswith(prefix):
+                print("%s" % line[offset:])
+
+    if len(args.probes) == 0:
+        print_probes(args.verbose, "*")
+    else:
+        for probe in args.probes:
+            print_probes(args.verbose, probe)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="QEMU SystemTap trace tool")
+    parser.add_argument("-v", "--verbose", help="Print verbose progress info",
+                        action='store_true')
+
+    subparser = parser.add_subparsers(help="commands")
+    subparser.required = True
+    subparser.dest = "command"
+
+    runparser = subparser.add_parser("run", help="Run a trace session",
+                                     formatter_class=argparse.RawDescriptionHelpFormatter,
+                                     epilog="""
+
+To watch all trace points on the qemu-system-x86_64 binary:
+
+   %(argv0)s run qemu-system-x86_64
+
+To only watch the trace points matching the qio* and qcrypto* patterns
+
+   %(argv0)s run qemu-system-x86_64 'qio*' 'qcrypto*'
+""" % {"argv0": sys.argv[0]})
+    runparser.set_defaults(func=cmd_run)
+    runparser.add_argument("--pid", "-p", dest="pid",
+                           help="Restrict tracing to a specific process ID")
+    runparser.add_argument("binary", help="QEMU system or user emulator binary")
+    runparser.add_argument("probes", help="Probe names or wildcards",
+                           nargs=argparse.REMAINDER)
+
+    listparser = subparser.add_parser("list", help="List probe points",
+                                      formatter_class=argparse.RawDescriptionHelpFormatter,
+                                      epilog="""
+
+To list all trace points on the qemu-system-x86_64 binary:
+
+   %(argv0)s list qemu-system-x86_64
+
+To only list the trace points matching the qio* and qcrypto* patterns
+
+   %(argv0)s list qemu-system-x86_64 'qio*' 'qcrypto*'
+""" % {"argv0": sys.argv[0]})
+    listparser.set_defaults(func=cmd_list)
+    listparser.add_argument("binary", help="QEMU system or user emulator binary")
+    listparser.add_argument("probes", help="Probe names or wildcards",
+                            nargs=argparse.REMAINDER)
+
+    args = parser.parse_args()
+
+    args.func(args)
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main()