Ubuntu Manpage: staprun - systemtap runtime

Provided by: systemtap-runtime_3.1-3ubuntu0.1_amd64

NAME

       staprun - systemtap runtime

SYNOPSIS

       staprun [ OPTIONS ] MODULE [ MODULE-OPTIONS ]

DESCRIPTION

       The  staprun  program  is  the back-end of the Systemtap tool.  It expects a kernel module
       produced by the front-end stap tool.

       Splitting the systemtap tool into a front-end and a back-end allows a user  to  compile  a
       systemtap script on a development machine that has the kernel development tools (needed to
       compile the script) and then transfer the resulting kernel module to a production  machine
       that doesn't have any development tools installed.

       Please  refer to stappaths (7) for the version number, or run rpm -q systemtap (fedora/red
       hat) apt-get -v systemtap (ubuntu)

OPTIONS

The staprun program supports the following options. Any other option prints a list of
supported options.

-v Verbose mode. The level of verbosity is also set in the SYSTEMTAP_VERBOSE
environment variable.

-V Print version number and exit.

-w Suppress warnings from the script.

-u Load the uprobes.ko module.

-c CMD Command CMD will be run and the staprun program will exit when CMD does. The
'_stp_target' variable will contain the pid for CMD.

-x PID The '_stp_target' variable will be set to PID.

-o FILE
Send output to FILE. If the module uses bulk mode, the output will be in percpu
files FILE_x(FILE_cpux in background and bulk mode) where 'x' is the cpu number.
This supports strftime(3) formats for FILE.

-b BUFFER_SIZE
The systemtap module will specify a buffer size. Setting one here will override
that value. The value should be an integer between 1 and 4095 which be assumed to
be the buffer size in MB. That value will be per-cpu if bulk mode is used.

-L Load module and start probes, then detach from the module leaving the probes
running. The module can be attached to later by using the -A option.

-A Attach to loaded systemtap module.

-C WHEN
Control coloring of error messages. WHEN must be either "never", "always", or
"auto" (i.e. enable only if at a terminal). If the option is missing, then "auto"
is assumed. Colors can be modified using the SYSTEMTAP_COLORS environment variable.
See the stap(1) manual page for more information on syntax and behaviour.

-d Delete a module. Only detached or unused modules the user has permission to access
will be deleted. Use "*" (quoted) to delete all unused modules.

-D Run staprun in background as a daemon and show it's pid.

-R Rename the module to a unique name before inserting it.

-r N:URI
Pass the given number and URI data to the tapset functions remote_id() and
remote_uri().

-S size[,N]
Sets the maximum size of output file and the maximum number of output files. If
the size of output file will exceed size , systemtap switches output file to the
next file. And if the number of output files exceed N , systemtap removes the
oldest output file. You can omit the second argument.

-T timeout
Sets maximum time reader thread will wait before dumping trace buffer. Value is in
ms, default is 200ms. Setting this to a high value decreases number of stapio wake-
ups, allowing deeper sleep for embedded platforms. But it impacts interactivity on
terminal as traces are dumped less often in case of low throughput. There is no
interactivity or performance impact for high throughput as trace is dumped when
buffer is full, before this timeout expires.

var1=val
Sets the value of global variable var1 to val. Global variables contained within a
module are treated as module options and can be set from the staprun command line.

ARGUMENTS

       MODULE is either a module path or a module name.  If it is a module name, the module  will
       be looked for in the following directory (where 'VERSION' is the output of "uname -r"):

              /lib/modules/VERSION/systemtap

       Any  additional  arguments on the command line are passed to the module.  One use of these
       additional module arguments is to set the value of global variables  declared  within  the
       module.

        $ stap -p4 -m mod1 -e 'global var1="foo"; probe begin{printf("%s\n", var1); exit()}'

       Running this with an additional module argument:

        $ staprun mod1.ko var1="HelloWorld"
        HelloWorld

       Spaces and exclamation marks currently cannot be passed into global variables this way.

EXAMPLES

       See the stapex(3stap) manual page for a collection of sample scripts.

       Here  is a very basic example of how to use staprun.  First, use stap to compile a script.
       The stap program will report the pathname to the resulting module.

        $ stap -p4 -e 'probe begin { printf("Hello World!\n"); exit() }'
        /home/user/.systemtap/cache/85/stap_8553d83f78c_265.ko

       Run staprun with the pathname to the module as an argument.

        $ staprun /home/user/.systemtap/cache/85/stap_8553d83f78c_265.ko
        Hello World!

MODULE DETACHING AND ATTACHING

       After the staprun program installs a Systemtap kernel module, users can  detach  from  the
       kernel  module and reattach to it later.  The -L option loads the module and automatically
       detaches.  Users can also detach from the  kernel  module  interactively  by  sending  the
       SIGQUIT signal from the keyboard (typically by typing Ctrl-\).

       To reattach to a kernel module, the staprun -A option would be used.

FILE SWITCHING BY SIGNAL

       After  staprun  launched the stapio program, users can command it to switch output file to
       next file when it outputs to file(s) (running staprun with -o option) by sending a SIGUSR2
       signal  to the stapio process. When it receives SIGUSR2, it will switch output file to new
       file with suffix .N where N is the sequential number.  For example,

        $ staprun -o foo ...

       outputs trace logs to foo and if it receives SIGUSR2 signal, it switches output  to  foo.1
       file. And receiving SIGUSR2 again, it switches to foo.2 file.

SAFETY AND SECURITY

Systemtap, in the default kernel-module runtime mode, is an administrative tool. It
exposes kernel internal data structures and potentially private user information. See the
stap(1) manual page for additional information on safety and security.

To increase system security, users of systemtap must be root, or in the staprun group in
order to execute this setuid staprun program. A user may select a particular privilege
level with the stap --privilege= option, which staprun will later enforce.

stapdev
Members of the stapdev group can write and load script modules with root-equivalent
privileges, without particular security constraints. (Many safety constraints
remain.)

stapsys
Members of the stapsys group have almost all the privileges of stapdev, except for
guru mode constructs.

staprun
Members only of the stapusr group may any-privileged modules placed into the
/lib/modules/VERSION/systemtap by the system administrator.

staprun
Members only of the stapusr group may also write and load low-privilege script
modules, which are normally limited to manipulating their own processes (and not
the kernel nor other users' processes).

Part of the privilege enforcement mechanism may require using a stap-server and
administrative trust in its cryptographic signer; see the stap-server(8) manual page for a
for more information.

On a kernel with FIPS mode enabled, staprun normally refuses to attempt to load systemtap-
generated kernel modules. This is because on some kernels, this results in a panic. If
your kernel includes corrections such as linux commit #002c77a48b47, then you can force
staprun to attempt module loads anyway, by setting the STAP_FIPS_OVERRIDE environment
variable to any value.

FILES

       /lib/modules/VERSION/systemtap
              If MODULE is a module name, the module will be looked for in this directory.  Users
              who are only in the 'stapusr' group can install modules located in this  directory.
              This directory must be owned by the root user and not be world writable.

BUGS

       Use   the   Bugzilla   link   of   the   project   web   page   or   our   mailing   list.
       http://sourceware.org/systemtap/, <systemtap@sourceware.org>.

                                                                                       STAPRUN(8)