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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |EXAMPLE |FILES |SEE ALSO |AUTHOR |REPORTING BUGS |LICENSE |RESOURCES |COPYING |NOTES |COLOPHON | |
LIBTRACEFS(3) libtracefs ManualLIBTRACEFS(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 longoffset, const char *fetchargs) struct tracefs_dynevent *tracefs_uretprobe_alloc(const char *system, const char *event, const char *file, unsigned long longoffset, const char *fetchargs)
tracefs_uprobe_alloc() allocates a new uprobe context. It will be in thesystem group (or uprobes ifsystem is NULL) and withevent name. The uprobe will be attached tooffset within thefile. The list of arguments, described infetchargs, will be fetched with the uprobe. The returned pointer to the user probe context must be freed withtracefs_dynevent_free(). The ubrobe is not configured in the system, tracefs_dynevent_* set of APIs can be used to configure it. Thetracefs_uretprobe_alloc() behaves the same astracefs_uprobe_alloc(), the only difference is that it allocates context to user return probe (uretprobe).
Thetracefs_uprobe_alloc() andtracefs_uretprobe_alloc() APIs return a pointer to an allocated tracefs_dynevent structure, describing the user probe. This pointer must be freed withtracefs_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 thelibtracefs (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 isnot part of the original manual page), send a mail to man-pages@man7.orglibtracefs 1.7.0 12/22/2023LIBTRACEFS(3)HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |