--- name: "stapprobes.signal" section: "5" platform: "linux" package: "systemtap" version: "0.0.20080705-1+lenny1" release: "Debian 5.0 (Lenny)" platforms: ["linux"] url: "https://new.carta.tech/stapprobes.signal" --- # stapprobes.signal(5) systemtap signal probe points ## NAME stapprobes.signal - systemtap signal probe points ## DESCRIPTION This family of probe points is used to probe signal activities. It contains the following probe points: - **signal.send** Fires when a signal is sent to a process **Arguments:** *sig*\ signal number *sig\_name*\ a string representation of the signal *sig\_pid*\ pid of the signal recipient process *pid\_name*\ name of the signal recipient process *si\_code*\ indicates the signal type *task*\ a task handle to the signal recipient *sinfo*\ the address of siginfo struct *shared*\ indicates whether this signal is shared by the thread group *send2queue*\ indicates whether this signal is sent to an existing sigqueue *name*\ name of the function used to send out this signal - **signal.send.return** Fires when return from sending a signal **Arguments:** *retstr*\ the return value Return values for "\_\_group\_send\_sig\_info" and "specific\_send\_sig\_info" \- return 0 if the signal is sucessfully sent to a process, which means the following: \<1\> the signal is ignored by receiving process \<2\> this is a non-RT signal and we already have one queued \<3\> the signal is successfully added into the sigqueue of receiving process \- return -EAGAIN if the sigqueue is overflow the signal was RT and sent by user using something other than kill() Return values for "send\_group\_sigqueue" \- return 0 if the signal is either sucessfully added into the sigqueue of receiving process or a SI\_TIMER entry is already queued so just increment the overrun count \- return 1 if this signal is ignored by receiving process Return values for "send\_sigqueue" \- return 0 if the signal is either sucessfully added into the sigqueue of receiving process or a SI\_TIMER entry is already queued so just increment the overrun count \- return 1 if this signal is ignored by receiving process \- return -1 if the task is marked exiting, so posix\_timer\_event can redirect it to the group leader *shared*\ indicates whether this signal is shared by the thread group *send2queue*\ indicates whether this signal is sent to an existing sigqueue *name*\ name of the function used to send out this signal - **signal.checkperm** Fires when check permissions for sending the signal **Arguments:** *sig*\ the number of the signal *sig\_name*\ a string representation of the signal *sig\_pid*\ pid of the signal recipient process *pid\_name*\ name of the signal recipient process *si\_code*\ indicates the signal type *task*\ a task handle to the signal recipient *sinfo*\ the address of siginfo struct *name*\ name of the probe point, is set to "signal.checkperm" - **signal.checkperm.return** Fires when return from permissions check for sending a signal **Arguments:** *retstr*\ the return value *name*\ name of the probe point, is set to "signal.checkperm" - **signal.wakeup** Fires when wake up the process for new active signals **Arguments:** *sig\_pid*\ pid of the process to be woke up *pid\_name*\ name of the process to be woke up *resume*\ indicate whether to wake up a task in STOPPED or TRACED state *state\_mask*\ a string representation indicate the mask of task states that can be woken. Possible values are (TASK\_INTERRUPTIBLE\|TASK\_STOPPED\|TASK\_TRACED) and TASK\_INTERRUPTIBLE. - **signal.check\_ignored** Fires when check whether the signal is ignored or not **Arguments:** *sig\_pid*\ pid of the signal recipient process *pid\_name*\ name of the signal recipient process *sig*\ the signal to be checked *sig\_name*\ name of the signal - **signal.check\_ignored.return** Fires when return from signal.check\_ignored **Arguments:** *retstr*\ return value. 0 indicate the current signal isn't ignored. - **signal.force\_segv** Forces SIGSEGV when there are some issues while handling signals for the process **Arguments:** *sig\_pid*\ pid of the signal recipient process *pid\_name*\ name of the signal recipient process *sig*\ the signal being handled *sig\_name*\ name of this signal - **signal.force\_segv.return** Fires when return from signal.force\_segv **Arguments:** *retstr*\ return value. Always return 0 - **signal.syskill** Fires when sys\_kill is called to send a signal to a process. **Arguments:** *pid*\ pid of the recipient process *sig*\ the signal to be sent - **signal.syskill.return** Fires when returning from sys\_kill - **signal.tgkill** Fires when sys\_tgkill is called to send a signal to one specific thread **Arguments:** *pid*\ pid of the recipient thread *tgid*\ thread group id which the target thread should have *sig*\ the signal to be sent - **signal.tgkill.return** Fires when returning from sys\_tgkill - **signal.tkill** Fires when sys\_tkill is called to send a signal to a single process. **Arguments:** *pid*\ pid of the recipient process *sig*\ the signal to be sent - **signal.tkill.return** Fires when returning from sys\_tkill - **signal.send\_sig\_queue** Fires when queue a signal to a process **Arguments:** *sig*\ the signal to be queued *sig\_name*\ name of this signal *sig\_pid*\ pid of the process to which the signal is queued *pid\_name*\ name of the process to which the signal is queued *sigqueue\_addr*\ address of the signal queue - **signal.send\_sig\_queue.return** Fires when return from signal.send\_sig\_queue **Arguments:** *retstr*\ return value - **signal.pending** Fires when examine the set of signals that are pending for delivery to the calling thread **Arguments:** *sigset\_add*\ address of user space sigset\_t *sigset\_size*\ sigset size - **signal.pending.return** Fires when return from signal.pending **Arguments:** *retstr*\ return value - **signal.handle** Fires when invoking the signal handler **Arguments:** *sig*\ signal number *sig\_name*\ signal name *sinfo*\ address of siginfo struct *sig\_code*\ the si\_code of siginfo *ka\_addr*\ Address of the k\_sigaction struct associated with the signal *oldset\_addr*\ Address of a bit mask array of blocked signals *sig\_mode*\ indicates whether the signal is a User Mode or Kernel mode Signal - **signal.handle.return** Fires when return from signal.handle **Arguments:** *retstr*\ return value of handle\_signal() - **signal.do\_action** Fires by calling thread to examine and change a signal action **Arguments:** *sig*\ signal number *sigact\_addr*\ address of the new sigaction struct associated with the signal *oldsigact\_addr*\ address of a previous sigaction struct associated with the signal *sa\_handler*\ the new handler of the signal *sa\_mask*\ the new mask of the signal - **signal.do\_action.return** Fires when return from signal.do\_action **Arguments:** *retstr*\ return value of do\_sigaction() - **signal.procmask** Fires by calling thread to examine and change blocked signals **Arguments:** *how*\ indicates how to change the blocked signals. \ Possible values are:\ SIG\_BLOCK=0 for blocking signals\ SIG\_UNBLOCK=1 for unblocking signals\ SIG\_SETMASK=2 for setting the signal mask *sigset\_addr*\ address of sigset\_t to be set *oldsigset\_addr*\ address of the old sigset\_t *sigset*\ the actual sigset to be set - **signal.procmask.return** Fires when return from signal.procmask **Arguments:** *retstr*\ return value of sigprocmask() - **signal.flush** Fires when flush all pending signals for a task **Arguments:** *task*\ the task handler of the process *sig\_pid*\ pid of the task *pid\_name*\ name of the task ## SEE ALSO [*stap*(1)](/stap/1.md), [*stapprobes*(5)](/stapprobes/5.md),