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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | COPYING | NOTES | COLOPHON |
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LIBTRACEFS(3) libtracefs Manual LIBTRACEFS(3)
tracefs_uprobe_alloc, tracefs_uretprobe_alloc - Allocate new user
(return) probe
#include <tracefs.h>
struct tracefs_dynevent *
tracefs_uprobe_alloc(const char *system, const char *event,
const char *file, unsigned long long offset, const char *fetchargs)
struct tracefs_dynevent *
tracefs_uretprobe_alloc(const char *system, const char *event,
const char *file, unsigned long long offset, const char *fetchargs)
tracefs_uprobe_alloc() allocates a new uprobe context. It will be
in the system group (or uprobes if system is NULL) and with event
name. The uprobe will be attached to offset within the file. The
list of arguments, described in fetchargs, will be fetched with
the uprobe. The returned pointer to the user probe context must be
freed with tracefs_dynevent_free(). The ubrobe is not configured
in the system, tracefs_dynevent_* set of APIs can be used to
configure it.
The tracefs_uretprobe_alloc() behaves the same as
tracefs_uprobe_alloc(), the only difference is that it allocates
context to user return probe (uretprobe).
The tracefs_uprobe_alloc() and tracefs_uretprobe_alloc() APIs
return a pointer to an allocated tracefs_dynevent structure,
describing the user probe. This pointer must be freed with
tracefs_dynevent_free(3). Note, this only allocates a descriptor
representing the uprobe. It does not modify the running system. On
error NULL is returned.
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <tracefs.h>
static int callback(struct tep_event *event, struct tep_record *record,
int cpu, void *data)
{
struct trace_seq seq;
trace_seq_init(&seq);
tep_print_event(event->tep, &seq, record, "%d-%s: %s",
TEP_PRINT_PID, TEP_PRINT_COMM, TEP_PRINT_NAME);
trace_seq_puts(&seq, "'\n");
trace_seq_terminate(&seq);
trace_seq_do_printf(&seq);
trace_seq_destroy(&seq);
return 0;
}
static pid_t run_exec(char **argv, char **env)
{
pid_t pid;
pid = fork();
if (pid)
return pid;
execve(argv[0], argv, env);
perror("exec");
exit(-1);
}
const char *myprobe = "my_urobes";
int main (int argc, char **argv, char **env)
{
struct tracefs_dynevent *uprobe, *uretprobe;
struct tep_handle *tep;
struct tracefs_instance *instance;
const char *sysnames[] = { myprobe, NULL };
long addr;
pid_t pid;
if (argc < 3) {
printf("usage: %s file_offset command\n", argv[0]);
exit(-1);
}
addr = strtol(argv[1], NULL, 0);
instance = tracefs_instance_create("exec_open");
if (!instance) {
perror("creating instance");
exit(-1);
}
tracefs_dynevent_destroy_all(TRACEFS_DYNEVENT_UPROBE|TRACEFS_DYNEVENT_URETPROBE, true);
uprobe = tracefs_uprobe_alloc(myprobe, "user_probe", argv[2], addr, NULL);
uretprobe = tracefs_uretprobe_alloc(myprobe, "user_retprobe", argv[2], addr, NULL);
if (!uprobe || !uretprobe) {
perror("allocating user probes");
exit(-1);
}
if (tracefs_dynevent_create(uprobe) ||
tracefs_dynevent_create(uretprobe)) {
perror("creating user probes");
exit(-1);
}
tep = tracefs_local_events_system(NULL, sysnames);
if (!tep) {
perror("reading events");
exit(-1);
}
tracefs_event_enable(instance, myprobe, "user_probe");
tracefs_event_enable(instance, myprobe, "user_retprobe");
pid = run_exec(&argv[2], env);
/* Let the child start to run */
sched_yield();
do {
tracefs_load_cmdlines(NULL, tep);
tracefs_iterate_raw_events(tep, instance, NULL, 0, callback, NULL);
} while (waitpid(pid, NULL, WNOHANG) != pid);
/* disable and destroy the events */
tracefs_dynevent_destroy(uprobe, true);
tracefs_dynevent_destroy(uretprobe, true);
tracefs_dynevent_free(uprobe);
tracefs_dynevent_free(uretprobe);
tracefs_instance_destroy(instance);
return 0;
}
tracefs.h
Header file to include in order to have access to the library APIs.
-ltracefs
Linker switch to add when building a program that uses the library.
libtracefs(3), libtraceevent(3), trace-cmd(1)
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2022 VMware, Inc. Free use of this software is
granted under the terms of the GNU Public License (GPL).
1. rostedt@goodmis.org
mailto:rostedt@goodmis.org
2. tz.stoyanov@gmail.com
mailto:tz.stoyanov@gmail.com
3. linux-trace-devel@vger.kernel.org
mailto:linux-trace-devel@vger.kernel.org
This page is part of the libtracefs (Linux kernel trace file
system library) project. Information about the project can be
found at ⟨https://www.trace-cmd.org/⟩. If you have a bug report
for this manual page, see ⟨https://www.trace-cmd.org/⟩. This page
was obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-06-02.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
libtracefs 1.7.0 12/22/2023 LIBTRACEFS(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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