scripts/tracetool/format/simpletrace_stap.py

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