NAME

       error::pass5 - systemtap pass-5 errors

DESCRIPTION

       Errors that occur during pass 5 (execution) can have a variety of causes.

       exceptional events during script execution
              The  systemtap  translator  and  runtime  include numerous error checks that aim to
              protect the systems and the users  from  mistakes  or  transient  conditions.   The
              script may deliberately call the error() tapset function to signal a problem.  Some
              memory needed for accessing $context  variables  may  be  temporarily  unavailable.
              Consider  using  the  try/catch  construct  to  wrap script fragments in exception-
              handling code.  Consider using the stap --suppress-handler-errors or  stap  --skip-
              badvars option.

       resource exhaustion
              One  of  several  types  of  space  or  time resource limits may be exceeded by the
              script, including system overload, too many tuples to be stored in an  array,  etc.
              Some  of  the  error  messages  identify the constraint by macro name, which may be
              individually raised.  Consider using the stap --suppress-handler-errors and/or stap
              -g  --suppress-time-limits  options.   Extend or disable individual resource limits
              using the stap -DSOME_LIMIT=NNNN option.  The stap -t  option  may  identify  those
              probes that are taking too long.

       remote execution server problems
              If  you  use  the  stap --remote option to direct a systemtap script to be executed
              somewhere else, ensure that an SSH connection may be made to the remote  host,  and
              that it has the current systemtap runtime installed & available.

       installation/permission problems
              It  is  possible  that  your  copy  of  systemtap was not correctly installed.  For
              example, the /usr/bin/staprun program may lack the necessary setuid permissions, or
              your  invoking  userid  might  not have sufficient privileges (root, or stapusr and
              related group memberships).  Environment  variables  may  interfere  with  locating
              /usr/libexec/.../stapio.

       security configuration
              SecureBoot  or  other  module  signing  machinery  may be in effect, preventing .ko
              module loading.  A local or  remote  stap-server  service  would  be  necessary  to
              securely  manage  keys.   This situation is detected automatically on most kernels,
              but on some, the SYSTEMTAP_SIGN environment varible may have to be set  to  trigger
              this extra signing-related processing.

              The  normal  kernel-module  based  systemtap  backend  may be more than your script
              requires.  Try stap --runtime=bpf and/or stap --runtime=dyninst  backends.   Though
              they  have  inherent limitations, they operate with lesser privileges and perceived
              risks.

              It may be possible to disable secure/lockdown measures temporarily with the SysRQ+x
              keystroke, or permanently with sudo mokutil --disable-validation and a reboot.

       errors from target program
              The program invoked by the stap -c CMD option may exit with a non-zero code.

       uncaught exceptions in the target program
              When  using  --runtime=dyninst  you may encounter an issue where the target program
              aborts with a  message  like  "terminate  called  after  throwing  an  instance  of
              'foo_exception'".   This  is unfortunately a limitation of Dyninst, which sometimes
              prevents exceptions from properly unwinding through instrumented code.

GATHERING MORE INFORMATION

       Increasing the verbosity of pass-5 with an option such as --vp 00001 can help pinpoint the
       problem.

SEE ALSO

       stap(1),
       http://sourceware.org/systemtap/wiki/TipExhaustedResourceErrors,
       error::fault(7stap),
       error::reporting(7stap)
       warning::pass5(7stap)

                                                                              ERROR::PASS5(7stap)