tracefs_uprobe_alloc(3) — Linux manual page
LIBTRACEFS(3) libtracefs Manual LIBTRACEFS(3)
NAME
tracefs_uprobe_alloc, tracefs_uretprobe_alloc - Allocate new user
(return) probe
SYNOPSIS
#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)
DESCRIPTION
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).
RETURN VALUE
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.
EXAMPLE
#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;
}
FILES
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.
SEE ALSO
libtracefs(3), libtraceevent(3), trace-cmd(1)
AUTHOR
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
REPORTING BUGS
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
LICENSE
libtracefs is Free Software licensed under the GNU LGPL 2.1
RESOURCES
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
COPYING
Copyright (C) 2022 VMware, Inc. Free use of this software is
granted under the terms of the GNU Public License (GPL).
NOTES
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
COLOPHON
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
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-05-17.) If you
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