scripts/tracetool/format/simpletrace_stap.py

   1 #!/usr/bin/env python
   2 # -*- coding: utf-8 -*-
   3
   4 """
   5 Generate .stp file that outputs simpletrace binary traces (DTrace with SystemTAP only).
   6 """
   7
   8 __author__     = "Stefan Hajnoczi <redhat.com>"
   9 __copyright__  = "Copyright (C) 2014, Red Hat, Inc."
  10 __license__    = "GPL version 2 or (at your option) any later version"
  11
  12 __maintainer__ = "Stefan Hajnoczi"
  13 __email__      = "stefanha@redhat.com"
  14
  15
  16 from tracetool import out
  17 from tracetool.backend.dtrace import probeprefix
  18 from tracetool.backend.simple import is_string
  19 from tracetool.format.stap import stap_escape
  20
  21 def global_var_name(name):
  22     return probeprefix().replace(".", "_") + "_" + name
  23
  24 def generate(events, backend, group):
  25     out('/* This file is autogenerated by tracetool, do not edit. */',
  26         '')
  27
  28     for event_id, e in enumerate(events):
  29         if 'disable' in e.properties:
  30             continue
  31
  32         out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',
  33             '{',
  34             probeprefix=probeprefix(),
  35             name=e.name)
  36
  37         # Calculate record size
  38         sizes = ['24'] # sizeof(TraceRecord)
  39         for type_, name in e.args:
  40             name = stap_escape(name)
  41             if is_string(type_):
  42                 out('    try {',
  43                     '        arg%(name)s_str = %(name)s ? user_string_n(%(name)s, 512) : "<null>"',
  44                     '    } catch {}',
  45                     '    arg%(name)s_len = strlen(arg%(name)s_str)',
  46                     name=name)
  47                 sizes.append('4 + arg%s_len' % name)
  48             else:
  49                 sizes.append('8')
  50         sizestr = ' + '.join(sizes)
  51
  52         # Generate format string and value pairs for record header and arguments
  53         fields = [('8b', str(event_id)),
  54                   ('8b', 'gettimeofday_ns()'),
  55                   ('4b', sizestr),
  56                   ('4b', 'pid()')]
  57         for type_, name in e.args:
  58             name = stap_escape(name)
  59             if is_string(type_):
  60                 fields.extend([('4b', 'arg%s_len' % name),
  61                                ('.*s', 'arg%s_len, arg%s_str' % (name, name))])
  62             else:
  63                 fields.append(('8b', name))
  64
  65         # Emit the entire record in a single SystemTap printf()
  66         fmt_str = '%'.join(fmt for fmt, _ in fields)
  67         arg_str = ', '.join(arg for _, arg in fields)
  68         out('    printf("%%8b%%%(fmt_str)s", 1, %(arg_str)s)',
  69             fmt_str=fmt_str, arg_str=arg_str)
  70
  71         out('}')
  72
  73     out()