tools/telemetry/build/linux_setup_msr.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2015 The Chromium Authors. All rights reserved.
   4 # Use of this source code is governed by a BSD-style license that can be
   5 # found in the LICENSE file.
   6 #
   7 # This is a script developers can use to set-up their workstation to let
   8 # Telemetry read the CPU's Model Specific Registers in order to get power
   9 # measurements. It can check if reading from MSRs is possible as any user, but
  10 # must run as root to make changes. Not all changes are sticky, so one has to
  11 # re-run this script after each reboot.
  12 #
  13 # This script is currently Debian/Ubuntu specific.
  14
  15 import os
  16 import subprocess
  17 import sys
  18
  19 MSR_DEV_FILE_PATH = '/dev/cpu/0/msr'
  20 RDMSR_PATH = '/usr/sbin/rdmsr'
  21
  22 def _Usage(prog_name):
  23   """Print a help message."""
  24   print 'Run "%s" as a regular user to check if reading from the MSR ' \
  25       'is possible.' % prog_name
  26   print 'Run "%s enable" as root to automatically set up reading from ' \
  27       'the MSR.' % prog_name
  28
  29
  30 def _CheckMsrKernelModule():
  31   """Return whether the 'msr' kernel module is loaded."""
  32   proc = subprocess.Popen('/sbin/lsmod', stdout=subprocess.PIPE)
  33   stdout = proc.communicate()[0]
  34   ret = proc.wait()
  35   if ret != 0:
  36     raise OSError('lsmod failed')
  37
  38   if not any([line.startswith('msr ') for line in stdout.splitlines()]):
  39     print 'Error: MSR module not loaded.'
  40     return False
  41
  42   return True
  43
  44
  45 def _CheckMsrDevNodes():
  46   """Check whether the MSR /dev files have the right permissions."""
  47   if not os.path.exists(MSR_DEV_FILE_PATH):
  48     print 'Error: %s does not exist.' % MSR_DEV_FILE_PATH
  49     return False
  50
  51   if not os.access(MSR_DEV_FILE_PATH, os.R_OK):
  52     print 'Error: Cannot read from %s' % MSR_DEV_FILE_PATH
  53     return False
  54
  55   return True
  56
  57
  58 def _CheckRdmsr():
  59   """Check and make sure /usr/sbin/rdmsr is set up correctly."""
  60   if not os.access(RDMSR_PATH, os.X_OK):
  61     print 'Error: %s missing or not executable.' % RDMSR_PATH
  62     return False
  63
  64   proc = subprocess.Popen(['/sbin/getcap', RDMSR_PATH], stdout=subprocess.PIPE)
  65   stdout = proc.communicate()[0]
  66   ret = proc.wait()
  67   if ret != 0:
  68     raise OSError('getcap failed')
  69
  70   if not 'cap_sys_rawio+ep' in stdout:
  71     print 'Error: /usr/sbin/rdmsr needs RAWIO capability.'
  72     return False
  73
  74   return True
  75
  76
  77 def _RunAllChecks():
  78   """Check to make sure it is possible to read from the MSRs."""
  79   if os.geteuid() == 0:
  80     print 'WARNING: Running as root, msr permission check likely inaccurate.'
  81
  82   has_dev_node = _CheckMsrDevNodes() if _CheckMsrKernelModule() else False
  83   has_rdmsr = _CheckRdmsr()
  84   return has_dev_node and has_rdmsr
  85
  86
  87 def _EnableMsr(prog_name):
  88   """Do all the setup needed to pass _RunAllChecks().
  89
  90   Needs to run as root."""
  91   if os.geteuid() != 0:
  92     print 'Error: Must run "%s enable" as root.' % prog_name
  93     return False
  94
  95   print 'Loading msr kernel module.'
  96   ret = subprocess.call(['/sbin/modprobe', 'msr'])
  97   if ret != 0:
  98     print 'Error: Cannot load msr module.'
  99     return False
 100
 101   print 'Running chmod on %s.' % MSR_DEV_FILE_PATH
 102   ret = subprocess.call(['/bin/chmod', 'a+r', MSR_DEV_FILE_PATH])
 103   if ret != 0:
 104     print 'Error: Cannot chmod %s.' % MSR_DEV_FILE_PATH
 105     return False
 106
 107   if not os.access(RDMSR_PATH, os.F_OK):
 108     print 'Need to install the msr-tools package.'
 109     ret = subprocess.call(['/usr/bin/apt-get', 'install', '-y', 'msr-tools'])
 110     if ret != 0:
 111       print 'Error: Did not successfully install msr-tools.'
 112       return False
 113
 114   print 'Running setcap on %s.' % RDMSR_PATH
 115   ret = subprocess.call(['/sbin/setcap', 'cap_sys_rawio+ep', RDMSR_PATH])
 116   if ret != 0:
 117     print 'Error: Cannot give /usr/sbin/rdmsr RAWIO capability.'
 118     return False
 119
 120   return True
 121
 122
 123 def main(prog_name, argv):
 124   if len(argv) == 0:
 125     if _RunAllChecks():
 126       print 'Check succeeded'
 127       return 0
 128
 129     print 'Check failed, try running "%s enable" as root to fix.' % prog_name
 130     return 1
 131
 132   if len(argv) == 1:
 133     if argv[0] == 'enable':
 134       return 0 if _EnableMsr(prog_name) else 1
 135
 136     print 'Error: Unknown sub-command %s' % argv[0]
 137     _Usage(prog_name)
 138     return 1
 139
 140   print 'Error: Bad number of arguments'
 141   _Usage(prog_name)
 142   return 1
 143
 144
 145 if '__main__' == __name__:
 146   sys.exit(main(os.path.basename(sys.argv[0]), sys.argv[1:]))