DTRACE_PROC(4) FreeBSD Kernel Interfaces Manual DTRACE_PROC(4)
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:
int pr_nlwp Number of threads in the process.
pid_t pr_pid Process ID.
pid_t pr_ppid Process ID of the parent process, or 0 if the
process does not have a parent.
pid_t pr_pgid Process ID of the process group leader.
pid_t pr_sid Session ID, or 0 if the process does not belong
to a session.
pid_t pr_uid Real user ID.
pid_t pr_euid Effective user ID.
pid_t pr_gid Real group ID.
pid_t pr_egid Effective group ID.
uintptr_t pr_addr Pointer to the struct proc for the process.
string pr_psargs Process arguments.
u_int pr_arglen Length of the process argument string.
u_int pr_jailid Jail ID of the process.
The fields of lwpsinfo_t are:
id_t pr_lwpid Thread ID.
int pr_flag Thread flags.
int pr_pri Real scheduling priority of the thread.
char pr_state Currently always 0.
char pr_sname Currently always `'?.
short pr_syscall Currently always 0.
uintptr_t pr_addr Pointer to the struct thread for the thread.
uintptr_t pr_wchan Current wait address on which the thread is
sleeping.
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>.
FreeBSD 13.1-RELEASE-p6 April 17, 2016 FreeBSD 13.1-RELEASE-p6
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