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 binary, probeprefix
  18 from tracetool.backend.simple import is_string
  19 from tracetool.format.stap import stap_escape
  20
  21
  22 def generate(events, backend):
  23     out('/* This file is autogenerated by tracetool, do not edit. */',
  24         '')
  25
  26     for event_id, e in enumerate(events):
  27         if 'disable' in e.properties:
  28             continue
  29
  30         out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',
  31             '{',
  32             probeprefix=probeprefix(),
  33             name=e.name)
  34
  35         # Calculate record size
  36         sizes = ['24'] # sizeof(TraceRecord)
  37         for type_, name in e.args:
  38             name = stap_escape(name)
  39             if is_string(type_):
  40                 out('    try {',
  41                     '        arg%(name)s_str = %(name)s ? user_string_n(%(name)s, 512) : "<null>"',
  42                     '    } catch {}',
  43                     '    arg%(name)s_len = strlen(arg%(name)s_str)',
  44                     name=name)
  45                 sizes.append('4 + arg%s_len' % name)
  46             else:
  47                 sizes.append('8')
  48         sizestr = ' + '.join(sizes)
  49
  50         # Generate format string and value pairs for record header and arguments
  51         fields = [('8b', str(event_id)),
  52                   ('8b', 'gettimeofday_ns()'),
  53                   ('4b', sizestr),
  54                   ('4b', 'pid()')]
  55         for type_, name in e.args:
  56             name = stap_escape(name)
  57             if is_string(type_):
  58                 fields.extend([('4b', 'arg%s_len' % name),
  59                                ('.*s', 'arg%s_len, arg%s_str' % (name, name))])
  60             else:
  61                 fields.append(('8b', name))
  62
  63         # Emit the entire record in a single SystemTap printf()
  64         fmt_str = '%'.join(fmt for fmt, _ in fields)
  65         arg_str = ', '.join(arg for _, arg in fields)
  66         out('    printf("%%%(fmt_str)s", %(arg_str)s)',
  67             fmt_str=fmt_str, arg_str=arg_str)
  68
  69         out('}')
  70
  71     out()