From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Add man pages that describe the following functions:
tracefs_kprobe_raw
tracefs_kretprobe_raw
tracefs_get_kprobes
tracefs_kprobe_info
tracefs_kprobe_clear_all
tracefs_kprobe_clear_probe
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
Documentation/libtracefs-kprobes.txt | 297 +++++++++++++++++++++++++++
1 file changed, 297 insertions(+)
create mode 100644 Documentation/libtracefs-kprobes.txt
diff --git a/Documentation/libtracefs-kprobes.txt b/Documentation/libtracefs-kprobes.txt
new file mode 100644
index 000000000000..c10576e2897e
--- /dev/null
+++ b/Documentation/libtracefs-kprobes.txt
@@ -0,0 +1,297 @@
+libtracefs(3)
+=============
+
+NAME
+----
+tracefs_kprobe_raw, tracefs_kretprobe_raw, tracefs_get_kprobes, tracefs_kprobe_info, tracefs_kprobe_clear_all, tracefs_kprobe_clear_probe - Create, list, and destroy kprobes
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <tracefs.h>*
+
+int tracefs_kprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
+int tracefs_kretprobe_raw(const char pass:[*]system, const char pass:[*]event, const char pass:[*]addr, const char pass:[*]format);
+char pass:[*]pass:[*]tracefs_get_kprobes(enum tracefs_kprobe_type type);
+enum tracefs_kprobe_type tracefs_kprobe_info(const char pass:[*]group, const char pass:[*]event,
+ char pass:[*]pass:[*]type, char pass:[*]pass:[*]addr, char pass:[*]pass:[*]format);
+enum tracefs_kprobe_type tracefs_kprobe_type(const char pass:[*]group, const char pass:[*]event)
+int tracefs_kprobe_clear_all(bool force);
+int tracefs_kprobe_clear_probe(const char pass:[*]system, const char pass:[*]event, bool force);
+--
+
+DESCRIPTION
+-----------
+*tracefs_kprobe_raw*() will create a kprobe event. If _system_ is NULL, then
+the default "kprobes" is used for the group (event system). Otherwise if _system_
+is specified then the kprobe will be created under the group by that name. The
+_event_ is the name of the kprobe event to create. The _addr_ can be a function,
+a function and offset, or a kernel address. This is where the location of the
+kprobe will be inserted in the kernel. The _format_ is the kprobe format as
+specified as FETCHARGS in the Linux kernel source in the Documentation/trace/kprobetrace.rst
+document.
+
+*tracefs_kretprobe_raw*() is the same as *tracefs_kprobe_raw()*, except that it
+creates a kretprobe instead of a kprobe. The difference is also described
+in the Linux kernel source in the Documentation/trace/kprobetrace.rst file.
+
+*tracefs_get_kprobes*() returns an array of strings (char pass:[*]) that contain
+the registered kprobes and kretprobes depending on the given _type_. If _type_ is
+TRACEFS_ALL_KPROBES, then all kprobes found are returned. If _type_ is
+TRACEFS_KPROBE, then only normal kprobes are returned. If _type_ is
+TRACEFS_KRETPROBE, then only kretprobes are returned.
+The names are in the "system/event" format.
+That is, one string holds both the kprobe's name as well as the group it is
+defined under. These strings are allocated and may be modified with the
+*strtok*(3) and *strtok_r*(3) functions. The string returned must be freed with
+*tracefs_list_free*(3).
+
+*tracefs_kprobe_info*() returns the type of the given kprobe. If _group_ is
+NULL, then the default "kprobes" is used. If _type_ is non NULL, then it will
+hold an allocated string that holds the type portion of the kprobe in the
+kprobe_events file (the content before the ":"). If _addr_ is non NULL, it will
+hold the address or function that the kprobe is attached to. If _format_ is non
+NULL, it will hold the format string of the kprobe. Note, that the content in
+_type_, _addr_, and _format_ must be freed with free(3) if they are set. Even
+in the case of an error, as they may hold information of what caused the error.
+
+*tracefs_kprobe_clear_all*() will try to remove all kprobes that have been
+registered. If the @force flag is set, it will then disable those kprobe events
+if they are enabled and then try to clear the kprobes.
+
+*tracefs_kprobe_clear_probe*() will try to clear specified kprobes. If _system_
+is NULL, then it will only clear the default kprobes under the "kprobes" group.
+If _event_ is NULL, it will clear all kprobes under the given _system_. If the
+_force_ flag is set, then it will disable the given kprobe events before clearing
+them.
+
+RETURN VALUE
+------------
+
+*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*(), *tracefs_kprobe_clear_all*(),
+and *tracefs_kprobe_clear_probe*() return 0 on success, or -1 on error.
+
+If a parsing error occurs on *tracefs_kprobe_raw*() or *tracefs_kretprobe_raw*()
+then *tracefs_error_last*(3) may be used to retrieve the error message explaining
+the parsing issue.
+
+*tracefs_get_kprobes*() returns an allocate string list of allocated strings
+on success that must be freed with *tracefs_list_free*(3) and returns
+NULL on error.
+
+*tracefs_kprobe_info*() returns the type of the given kprobe. It returns
+TRACEFS_KPROBE for normal kprobes, TRACEFS_KRETPROBE for kretprobes, and
+on error, or if the kprobe is not found TRACEFS_ALL_KPROBES is returned.
+If _type_, _addr_, or _format_ are non NULL, they will contain allocated
+strings that must be freed by free(3) even in the case of error.
+
+ERRORS
+------
+The following errors are for all the above calls:
+
+*EPERM* Not run as root user
+
+*ENODEV* Kprobe events are not configured for the running kernel.
+
+*ENOMEM* Memory allocation error.
+
+*tracefs_kprobe_raw*(), *tracefs_kretprobe_raw*() can fail with the following errors:
+
+*EBADMSG* Either _addr_ or _format_ are NULL.
+
+*EINVAL* Most likely a parsing error occurred (use *tracefs_error_last*(3) to possibly
+ see what that error was).
+
+Other errors may also happen caused by internal system calls.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include <tracefs/tracefs.h>
+
+static struct tep_event *open_event;
+static struct tep_format_field *file_field;
+
+static struct tep_event *openret_event;
+static struct tep_format_field *ret_field;
+
+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: ", TEP_PRINT_PID, TEP_PRINT_COMM);
+
+ if (event->id == open_event->id) {
+ trace_seq_puts(&seq, "open file='");
+ tep_print_field(&seq, record->data, file_field);
+ trace_seq_puts(&seq, "'\n");
+ } else if (event->id == openret_event->id) {
+ unsigned long long ret;
+ tep_read_number_field(ret_field, record->data, &ret);
+ trace_seq_printf(&seq, "open ret=%lld\n", ret);
+ } else {
+ goto out;
+ }
+
+ trace_seq_terminate(&seq);
+ trace_seq_do_printf(&seq);
+out:
+ 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 *mykprobe = "my_kprobes";
+
+enum kprobe_type {
+ KPROBE,
+ KRETPROBE,
+};
+
+static void __kprobe_create(enum kprobe_type type, const char *event,
+ const char *addr, const char *fmt)
+{
+ char *err;
+ int r;
+
+ if (type == KPROBE)
+ r = tracefs_kprobe_raw(mykprobe, event, addr, fmt);
+ else
+ r = tracefs_kretprobe_raw(mykprobe, event, addr, fmt);
+ if (r < 0) {
+ err = tracefs_error_last(NULL);
+ perror("Failed to create kprobe:");
+ if (err && strlen(err))
+ fprintf(stderr, "%s\n", err);
+ }
+}
+
+static void kprobe_create(const char *event, const char *addr,
+ const char *fmt)
+{
+ __kprobe_create(KPROBE, event, addr, fmt);
+}
+
+static void kretprobe_create(const char *event, const char *addr,
+ const char *fmt)
+{
+ __kprobe_create(KRETPROBE, event, addr, fmt);
+}
+
+int main (int argc, char **argv, char **env)
+{
+ struct tracefs_instance *instance;
+ struct tep_handle *tep;
+ const char *sysnames[] = { mykprobe, NULL };
+ pid_t pid;
+
+ if (argc < 2) {
+ printf("usage: %s command\n", argv[0]);
+ exit(-1);
+ }
+
+ instance = tracefs_instance_create("exec_open");
+ if (!instance) {
+ perror("creating instance");
+ exit(-1);
+ }
+
+ tracefs_kprobe_clear_probe(mykprobe, NULL, true);
+
+ kprobe_create("open", "do_sys_openat2",
+ "file=+0($arg2):ustring flags=+0($arg3):x64 mode=+8($arg3):x64\n");
+
+ kretprobe_create("openret", "do_sys_openat2", "ret=%ax");
+
+ tep = tracefs_local_events_system(NULL, sysnames);
+ if (!tep) {
+ perror("reading events");
+ exit(-1);
+ }
+ open_event = tep_find_event_by_name(tep, mykprobe, "open");
+ file_field = tep_find_field(open_event, "file");
+
+ openret_event = tep_find_event_by_name(tep, mykprobe, "openret");
+ ret_field = tep_find_field(openret_event, "ret");
+
+ tracefs_event_enable(instance, mykprobe, NULL);
+ pid = run_exec(&argv[1], 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);
+
+ /* Will disable the events */
+ tracefs_kprobe_clear_probe(mykprobe, NULL, true);
+ tracefs_instance_destroy(instance);
+ tep_free(tep);
+
+ return 0;
+}
+--
+
+FILES
+-----
+[verse]
+--
+*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
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@xxxxxxxxxxx>
+*Tzvetomir Stoyanov* <tz.stoyanov@xxxxxxxxx>
+*sameeruddin shaik* <sameeruddin.shaik8@xxxxxxxxx>
+--
+REPORTING BUGS
+--------------
+Report bugs to <linux-trace-devel@xxxxxxxxxxxxxxx>
+
+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) 2020 VMware, Inc. Free use of this software is granted under
+the terms of the GNU Public License (GPL).
--
2.30.2
|