Ubuntu Manpage: staprun - systemtap runtime

Provided by: systemtap-runtime_4.6-2_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 delet‐
ed. 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 out‐
put 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 argu‐
ment.

-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  mod‐
       ule 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 pro‐
       gram 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  re‐
       ceiving 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 in‐
ternal data structures and potentially private user information. See the stap(1) manual page for addi‐
tional information on safety and security.

To increase system security, users of systemtap must be root, or in the stapusr 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 con‐
structs.

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

stapusr
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' process‐
es).

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 ker‐
nel modules. This is because on some kernels, this results in a panic. If your kernel includes correc‐
tions 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)