NAME¶

dtrace_proc — a DTrace provider for tracing events related to user processes

SYNOPSIS¶

proc:::create(struct proc *, struct proc *, int);

proc:::exec(char *);

proc:::exec-failure(int);

proc:::exec-success(char *);

proc:::exit(int);

proc:::signal-clear(int, ksiginfo_t *);

proc:::signal-discard(struct thread *, struct proc *, int);

proc:::signal-send(struct thread *, struct proc *, int);

DESCRIPTION¶

The DTrace proc provider provides insight into events related to user processes: process and thread creation and termination events, and process signalling.

The proc:::create() probe fires when a user process is created via the fork(2), vfork(2), pdfork(2), or rfork(2) system calls. In particular, kernel processes created with the kproc(9) KPI will not trigger this probe. The proc:::create() probe's first two arguments are the new child process and its parent, respectively. The third argument is a mask of rfork(2) flags indicating which process resources are to be shared between the parent and child processes.

The proc:::exec() probe fires when a process attempts to execute a file. Its argument is the specified filename for the file. If the attempt fails because of an error, the proc:::exec-failure() probe will subsequently fire, providing the corresponding errno(2) value in its first argument. Otherwise, the proc:::exec-success() probe will fire.

The proc:::exit() probe fires when a process exits or is terminated. Its argument is the corresponding SIGCHLD signal code; valid values are documented in the siginfo(3) manual page and defined in signal.h. For example, when a process exits normally, the value of args[0] will be CLD_EXITED.

The proc:::signal-send() probe fires when a signal is about to be sent to a process. The proc:::signal-discard() probe fires when a signal is sent to a process that ignores it. This probe will fire after the proc:::signal-send() probe for the signal in question. The arguments to these probes are the thread and process to which the signal will be sent, and the signal number of the signal. Valid signal numbers are defined in the signal(3) manual page. The proc:::signal-clear() probe fires when a pending signal has been cleared by one of the sigwait(2), sigtimedwait(2), or sigwaitinfo(2) system calls. Its arguments are the signal number of the cleared signal, and a pointer to the corresponding signal information. The siginfo_t for the signal can be obtained from args[1]->ksi_info.

ARGUMENTS¶

Though the proc provider probes use native FreeBSD arguments types, standard D types for processes and threads are available. These are psinfo_t and lwpsinfo_t respectively, and are defined in /usr/lib/dtrace/psinfo.d. This file also defines two global variables, curpsinfo and curlwpsinfo, which provide representations of the current process and thread using these types.

The fields of psinfo_t are:

The fields of lwpsinfo_t are:

FILES¶

/usr/lib/dtrace/psinfo.d

DTrace type and translator definitions for the proc provider.

EXAMPLES¶

The following script logs process execution events as they occur:

#pragma D option quiet

proc:::exec-success
{
        printf("%s", curpsinfo->pr_psargs);
}

Note that the pr_psargs field is subject to the limit defined by the kern.ps_arg_cache_limit sysctl. In particular, processes with an argument list longer than the value defined by this sysctl cannot be logged in this way.

COMPATIBILITY¶

The proc provider in FreeBSD is not compatible with the proc provider in Solaris. In particular, FreeBSD uses the native struct proc and struct thread types for probe arguments rather than translated types. Additionally, a number of proc provider probes found in Solaris are not currently available on FreeBSD.

SEE ALSO¶

dtrace(1), errno(2), fork(2), pdfork(2), rfork(2), vfork(2), siginfo(3), signal(3), dtrace_sched(4), kproc(9)

HISTORY¶

The proc provider first appeared in FreeBSD 7.1.

AUTHORS¶

This manual page was written by Mark Johnston <markj@FreeBSD.org>.