linux/kernel/trace/trace_eprobe.c
Masami Hiramatsu (Google) 25f00e40ce tracing/probes: Support $argN in return probe (kprobe and fprobe)
Support accessing $argN in the return probe events. This will help users to
record entry data in function return (exit) event for simplfing the function
entry/exit information in one event, and record the result values (e.g.
allocated object/initialized object) at function exit.

For example, if we have a function `int init_foo(struct foo *obj, int param)`
sometimes we want to check how `obj` is initialized. In such case, we can
define a new return event like below;

 # echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events

Thus it records the function parameter `param` and its result `obj->field1`
(the dereference will be done in the function exit timing) value at once.

This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF
is enabled, we can trace both function parameters and the return value
by following command.

 # echo 'f target_function%return $arg* $retval' >> dynamic_events

Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-03-07 00:27:34 +09:00

985 lines
22 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* event probes
*
* Part of this code was copied from kernel/trace/trace_kprobe.c written by
* Masami Hiramatsu <mhiramat@kernel.org>
*
* Copyright (C) 2021, VMware Inc, Steven Rostedt <rostedt@goodmis.org>
* Copyright (C) 2021, VMware Inc, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
*
*/
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/ftrace.h>
#include "trace_dynevent.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
#include "trace_probe_kernel.h"
#define EPROBE_EVENT_SYSTEM "eprobes"
struct trace_eprobe {
/* tracepoint system */
const char *event_system;
/* tracepoint event */
const char *event_name;
/* filter string for the tracepoint */
char *filter_str;
struct trace_event_call *event;
struct dyn_event devent;
struct trace_probe tp;
};
struct eprobe_data {
struct trace_event_file *file;
struct trace_eprobe *ep;
};
#define for_each_trace_eprobe_tp(ep, _tp) \
list_for_each_entry(ep, trace_probe_probe_list(_tp), tp.list)
static int __trace_eprobe_create(int argc, const char *argv[]);
static void trace_event_probe_cleanup(struct trace_eprobe *ep)
{
if (!ep)
return;
trace_probe_cleanup(&ep->tp);
kfree(ep->event_name);
kfree(ep->event_system);
if (ep->event)
trace_event_put_ref(ep->event);
kfree(ep->filter_str);
kfree(ep);
}
static struct trace_eprobe *to_trace_eprobe(struct dyn_event *ev)
{
return container_of(ev, struct trace_eprobe, devent);
}
static int eprobe_dyn_event_create(const char *raw_command)
{
return trace_probe_create(raw_command, __trace_eprobe_create);
}
static int eprobe_dyn_event_show(struct seq_file *m, struct dyn_event *ev)
{
struct trace_eprobe *ep = to_trace_eprobe(ev);
int i;
seq_printf(m, "e:%s/%s", trace_probe_group_name(&ep->tp),
trace_probe_name(&ep->tp));
seq_printf(m, " %s.%s", ep->event_system, ep->event_name);
for (i = 0; i < ep->tp.nr_args; i++)
seq_printf(m, " %s=%s", ep->tp.args[i].name, ep->tp.args[i].comm);
seq_putc(m, '\n');
return 0;
}
static int unregister_trace_eprobe(struct trace_eprobe *ep)
{
/* If other probes are on the event, just unregister eprobe */
if (trace_probe_has_sibling(&ep->tp))
goto unreg;
/* Enabled event can not be unregistered */
if (trace_probe_is_enabled(&ep->tp))
return -EBUSY;
/* Will fail if probe is being used by ftrace or perf */
if (trace_probe_unregister_event_call(&ep->tp))
return -EBUSY;
unreg:
dyn_event_remove(&ep->devent);
trace_probe_unlink(&ep->tp);
return 0;
}
static int eprobe_dyn_event_release(struct dyn_event *ev)
{
struct trace_eprobe *ep = to_trace_eprobe(ev);
int ret = unregister_trace_eprobe(ep);
if (!ret)
trace_event_probe_cleanup(ep);
return ret;
}
static bool eprobe_dyn_event_is_busy(struct dyn_event *ev)
{
struct trace_eprobe *ep = to_trace_eprobe(ev);
return trace_probe_is_enabled(&ep->tp);
}
static bool eprobe_dyn_event_match(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev)
{
struct trace_eprobe *ep = to_trace_eprobe(ev);
const char *slash;
/*
* We match the following:
* event only - match all eprobes with event name
* system and event only - match all system/event probes
* system only - match all system probes
*
* The below has the above satisfied with more arguments:
*
* attached system/event - If the arg has the system and event
* the probe is attached to, match
* probes with the attachment.
*
* If any more args are given, then it requires a full match.
*/
/*
* If system exists, but this probe is not part of that system
* do not match.
*/
if (system && strcmp(trace_probe_group_name(&ep->tp), system) != 0)
return false;
/* Must match the event name */
if (event[0] != '\0' && strcmp(trace_probe_name(&ep->tp), event) != 0)
return false;
/* No arguments match all */
if (argc < 1)
return true;
/* First argument is the system/event the probe is attached to */
slash = strchr(argv[0], '/');
if (!slash)
slash = strchr(argv[0], '.');
if (!slash)
return false;
if (strncmp(ep->event_system, argv[0], slash - argv[0]))
return false;
if (strcmp(ep->event_name, slash + 1))
return false;
argc--;
argv++;
/* If there are no other args, then match */
if (argc < 1)
return true;
return trace_probe_match_command_args(&ep->tp, argc, argv);
}
static struct dyn_event_operations eprobe_dyn_event_ops = {
.create = eprobe_dyn_event_create,
.show = eprobe_dyn_event_show,
.is_busy = eprobe_dyn_event_is_busy,
.free = eprobe_dyn_event_release,
.match = eprobe_dyn_event_match,
};
static struct trace_eprobe *alloc_event_probe(const char *group,
const char *this_event,
struct trace_event_call *event,
int nargs)
{
struct trace_eprobe *ep;
const char *event_name;
const char *sys_name;
int ret = -ENOMEM;
if (!event)
return ERR_PTR(-ENODEV);
sys_name = event->class->system;
event_name = trace_event_name(event);
ep = kzalloc(struct_size(ep, tp.args, nargs), GFP_KERNEL);
if (!ep) {
trace_event_put_ref(event);
goto error;
}
ep->event = event;
ep->event_name = kstrdup(event_name, GFP_KERNEL);
if (!ep->event_name)
goto error;
ep->event_system = kstrdup(sys_name, GFP_KERNEL);
if (!ep->event_system)
goto error;
ret = trace_probe_init(&ep->tp, this_event, group, false, nargs);
if (ret < 0)
goto error;
dyn_event_init(&ep->devent, &eprobe_dyn_event_ops);
return ep;
error:
trace_event_probe_cleanup(ep);
return ERR_PTR(ret);
}
static int eprobe_event_define_fields(struct trace_event_call *event_call)
{
struct eprobe_trace_entry_head field;
struct trace_probe *tp;
tp = trace_probe_primary_from_call(event_call);
if (WARN_ON_ONCE(!tp))
return -ENOENT;
return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
}
static struct trace_event_fields eprobe_fields_array[] = {
{ .type = TRACE_FUNCTION_TYPE,
.define_fields = eprobe_event_define_fields },
{}
};
/* Event entry printers */
static enum print_line_t
print_eprobe_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct eprobe_trace_entry_head *field;
struct trace_event_call *pevent;
struct trace_event *probed_event;
struct trace_seq *s = &iter->seq;
struct trace_eprobe *ep;
struct trace_probe *tp;
unsigned int type;
field = (struct eprobe_trace_entry_head *)iter->ent;
tp = trace_probe_primary_from_call(
container_of(event, struct trace_event_call, event));
if (WARN_ON_ONCE(!tp))
goto out;
ep = container_of(tp, struct trace_eprobe, tp);
type = ep->event->event.type;
trace_seq_printf(s, "%s: (", trace_probe_name(tp));
probed_event = ftrace_find_event(type);
if (probed_event) {
pevent = container_of(probed_event, struct trace_event_call, event);
trace_seq_printf(s, "%s.%s", pevent->class->system,
trace_event_name(pevent));
} else {
trace_seq_printf(s, "%u", type);
}
trace_seq_putc(s, ')');
if (trace_probe_print_args(s, tp->args, tp->nr_args,
(u8 *)&field[1], field) < 0)
goto out;
trace_seq_putc(s, '\n');
out:
return trace_handle_return(s);
}
static nokprobe_inline unsigned long
get_event_field(struct fetch_insn *code, void *rec)
{
struct ftrace_event_field *field = code->data;
unsigned long val;
void *addr;
addr = rec + field->offset;
if (is_string_field(field)) {
switch (field->filter_type) {
case FILTER_DYN_STRING:
val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
break;
case FILTER_RDYN_STRING:
val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
break;
case FILTER_STATIC_STRING:
val = (unsigned long)addr;
break;
case FILTER_PTR_STRING:
val = (unsigned long)(*(char *)addr);
break;
default:
WARN_ON_ONCE(1);
return 0;
}
return val;
}
switch (field->size) {
case 1:
if (field->is_signed)
val = *(char *)addr;
else
val = *(unsigned char *)addr;
break;
case 2:
if (field->is_signed)
val = *(short *)addr;
else
val = *(unsigned short *)addr;
break;
case 4:
if (field->is_signed)
val = *(int *)addr;
else
val = *(unsigned int *)addr;
break;
default:
if (field->is_signed)
val = *(long *)addr;
else
val = *(unsigned long *)addr;
break;
}
return val;
}
static int get_eprobe_size(struct trace_probe *tp, void *rec)
{
struct fetch_insn *code;
struct probe_arg *arg;
int i, len, ret = 0;
for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (arg->dynamic) {
unsigned long val;
code = arg->code;
retry:
switch (code->op) {
case FETCH_OP_TP_ARG:
val = get_event_field(code, rec);
break;
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
if (process_common_fetch_insn(code, &val) < 0)
continue;
}
code++;
len = process_fetch_insn_bottom(code, val, NULL, NULL);
if (len > 0)
ret += len;
}
}
return ret;
}
/* Kprobe specific fetch functions */
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
void *dest, void *base)
{
unsigned long val;
int ret;
retry:
switch (code->op) {
case FETCH_OP_TP_ARG:
val = get_event_field(code, rec);
break;
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
ret = process_common_fetch_insn(code, &val);
if (ret < 0)
return ret;
}
code++;
return process_fetch_insn_bottom(code, val, dest, base);
}
NOKPROBE_SYMBOL(process_fetch_insn)
/* eprobe handler */
static inline void
__eprobe_trace_func(struct eprobe_data *edata, void *rec)
{
struct eprobe_trace_entry_head *entry;
struct trace_event_call *call = trace_probe_event_call(&edata->ep->tp);
struct trace_event_buffer fbuffer;
int dsize;
if (WARN_ON_ONCE(call != edata->file->event_call))
return;
if (trace_trigger_soft_disabled(edata->file))
return;
dsize = get_eprobe_size(&edata->ep->tp, rec);
entry = trace_event_buffer_reserve(&fbuffer, edata->file,
sizeof(*entry) + edata->ep->tp.size + dsize);
if (!entry)
return;
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
store_trace_args(&entry[1], &edata->ep->tp, rec, NULL, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
}
/*
* The event probe implementation uses event triggers to get access to
* the event it is attached to, but is not an actual trigger. The below
* functions are just stubs to fulfill what is needed to use the trigger
* infrastructure.
*/
static int eprobe_trigger_init(struct event_trigger_data *data)
{
return 0;
}
static void eprobe_trigger_free(struct event_trigger_data *data)
{
}
static int eprobe_trigger_print(struct seq_file *m,
struct event_trigger_data *data)
{
/* Do not print eprobe event triggers */
return 0;
}
static void eprobe_trigger_func(struct event_trigger_data *data,
struct trace_buffer *buffer, void *rec,
struct ring_buffer_event *rbe)
{
struct eprobe_data *edata = data->private_data;
if (unlikely(!rec))
return;
__eprobe_trace_func(edata, rec);
}
static struct event_trigger_ops eprobe_trigger_ops = {
.trigger = eprobe_trigger_func,
.print = eprobe_trigger_print,
.init = eprobe_trigger_init,
.free = eprobe_trigger_free,
};
static int eprobe_trigger_cmd_parse(struct event_command *cmd_ops,
struct trace_event_file *file,
char *glob, char *cmd,
char *param_and_filter)
{
return -1;
}
static int eprobe_trigger_reg_func(char *glob,
struct event_trigger_data *data,
struct trace_event_file *file)
{
return -1;
}
static void eprobe_trigger_unreg_func(char *glob,
struct event_trigger_data *data,
struct trace_event_file *file)
{
}
static struct event_trigger_ops *eprobe_trigger_get_ops(char *cmd,
char *param)
{
return &eprobe_trigger_ops;
}
static struct event_command event_trigger_cmd = {
.name = "eprobe",
.trigger_type = ETT_EVENT_EPROBE,
.flags = EVENT_CMD_FL_NEEDS_REC,
.parse = eprobe_trigger_cmd_parse,
.reg = eprobe_trigger_reg_func,
.unreg = eprobe_trigger_unreg_func,
.unreg_all = NULL,
.get_trigger_ops = eprobe_trigger_get_ops,
.set_filter = NULL,
};
static struct event_trigger_data *
new_eprobe_trigger(struct trace_eprobe *ep, struct trace_event_file *file)
{
struct event_trigger_data *trigger;
struct event_filter *filter = NULL;
struct eprobe_data *edata;
int ret;
edata = kzalloc(sizeof(*edata), GFP_KERNEL);
trigger = kzalloc(sizeof(*trigger), GFP_KERNEL);
if (!trigger || !edata) {
ret = -ENOMEM;
goto error;
}
trigger->flags = EVENT_TRIGGER_FL_PROBE;
trigger->count = -1;
trigger->ops = &eprobe_trigger_ops;
/*
* EVENT PROBE triggers are not registered as commands with
* register_event_command(), as they are not controlled by the user
* from the trigger file
*/
trigger->cmd_ops = &event_trigger_cmd;
INIT_LIST_HEAD(&trigger->list);
if (ep->filter_str) {
ret = create_event_filter(file->tr, ep->event,
ep->filter_str, false, &filter);
if (ret)
goto error;
}
RCU_INIT_POINTER(trigger->filter, filter);
edata->file = file;
edata->ep = ep;
trigger->private_data = edata;
return trigger;
error:
free_event_filter(filter);
kfree(edata);
kfree(trigger);
return ERR_PTR(ret);
}
static int enable_eprobe(struct trace_eprobe *ep,
struct trace_event_file *eprobe_file)
{
struct event_trigger_data *trigger;
struct trace_event_file *file;
struct trace_array *tr = eprobe_file->tr;
file = find_event_file(tr, ep->event_system, ep->event_name);
if (!file)
return -ENOENT;
trigger = new_eprobe_trigger(ep, eprobe_file);
if (IS_ERR(trigger))
return PTR_ERR(trigger);
list_add_tail_rcu(&trigger->list, &file->triggers);
trace_event_trigger_enable_disable(file, 1);
update_cond_flag(file);
return 0;
}
static struct trace_event_functions eprobe_funcs = {
.trace = print_eprobe_event
};
static int disable_eprobe(struct trace_eprobe *ep,
struct trace_array *tr)
{
struct event_trigger_data *trigger = NULL, *iter;
struct trace_event_file *file;
struct event_filter *filter;
struct eprobe_data *edata;
file = find_event_file(tr, ep->event_system, ep->event_name);
if (!file)
return -ENOENT;
list_for_each_entry(iter, &file->triggers, list) {
if (!(iter->flags & EVENT_TRIGGER_FL_PROBE))
continue;
edata = iter->private_data;
if (edata->ep == ep) {
trigger = iter;
break;
}
}
if (!trigger)
return -ENODEV;
list_del_rcu(&trigger->list);
trace_event_trigger_enable_disable(file, 0);
update_cond_flag(file);
/* Make sure nothing is using the edata or trigger */
tracepoint_synchronize_unregister();
filter = rcu_access_pointer(trigger->filter);
if (filter)
free_event_filter(filter);
kfree(edata);
kfree(trigger);
return 0;
}
static int enable_trace_eprobe(struct trace_event_call *call,
struct trace_event_file *file)
{
struct trace_probe *tp;
struct trace_eprobe *ep;
bool enabled;
int ret = 0;
int cnt = 0;
tp = trace_probe_primary_from_call(call);
if (WARN_ON_ONCE(!tp))
return -ENODEV;
enabled = trace_probe_is_enabled(tp);
/* This also changes "enabled" state */
if (file) {
ret = trace_probe_add_file(tp, file);
if (ret)
return ret;
} else
trace_probe_set_flag(tp, TP_FLAG_PROFILE);
if (enabled)
return 0;
for_each_trace_eprobe_tp(ep, tp) {
ret = enable_eprobe(ep, file);
if (ret)
break;
enabled = true;
cnt++;
}
if (ret) {
/* Failed to enable one of them. Roll back all */
if (enabled) {
/*
* It's a bug if one failed for something other than memory
* not being available but another eprobe succeeded.
*/
WARN_ON_ONCE(ret != -ENOMEM);
for_each_trace_eprobe_tp(ep, tp) {
disable_eprobe(ep, file->tr);
if (!--cnt)
break;
}
}
if (file)
trace_probe_remove_file(tp, file);
else
trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
}
return ret;
}
static int disable_trace_eprobe(struct trace_event_call *call,
struct trace_event_file *file)
{
struct trace_probe *tp;
struct trace_eprobe *ep;
tp = trace_probe_primary_from_call(call);
if (WARN_ON_ONCE(!tp))
return -ENODEV;
if (file) {
if (!trace_probe_get_file_link(tp, file))
return -ENOENT;
if (!trace_probe_has_single_file(tp))
goto out;
trace_probe_clear_flag(tp, TP_FLAG_TRACE);
} else
trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
if (!trace_probe_is_enabled(tp)) {
for_each_trace_eprobe_tp(ep, tp)
disable_eprobe(ep, file->tr);
}
out:
if (file)
/*
* Synchronization is done in below function. For perf event,
* file == NULL and perf_trace_event_unreg() calls
* tracepoint_synchronize_unregister() to ensure synchronize
* event. We don't need to care about it.
*/
trace_probe_remove_file(tp, file);
return 0;
}
static int eprobe_register(struct trace_event_call *event,
enum trace_reg type, void *data)
{
struct trace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return enable_trace_eprobe(event, file);
case TRACE_REG_UNREGISTER:
return disable_trace_eprobe(event, file);
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
case TRACE_REG_PERF_UNREGISTER:
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}
static inline void init_trace_eprobe_call(struct trace_eprobe *ep)
{
struct trace_event_call *call = trace_probe_event_call(&ep->tp);
call->flags = TRACE_EVENT_FL_EPROBE;
call->event.funcs = &eprobe_funcs;
call->class->fields_array = eprobe_fields_array;
call->class->reg = eprobe_register;
}
static struct trace_event_call *
find_and_get_event(const char *system, const char *event_name)
{
struct trace_event_call *tp_event;
const char *name;
list_for_each_entry(tp_event, &ftrace_events, list) {
/* Skip other probes and ftrace events */
if (tp_event->flags &
(TRACE_EVENT_FL_IGNORE_ENABLE |
TRACE_EVENT_FL_KPROBE |
TRACE_EVENT_FL_UPROBE |
TRACE_EVENT_FL_EPROBE))
continue;
if (!tp_event->class->system ||
strcmp(system, tp_event->class->system))
continue;
name = trace_event_name(tp_event);
if (!name || strcmp(event_name, name))
continue;
if (!trace_event_try_get_ref(tp_event))
return NULL;
return tp_event;
}
return NULL;
}
static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[], int i)
{
struct traceprobe_parse_context ctx = {
.event = ep->event,
.flags = TPARG_FL_KERNEL | TPARG_FL_TEVENT,
};
int ret;
ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], &ctx);
/* Handle symbols "@" */
if (!ret)
ret = traceprobe_update_arg(&ep->tp.args[i]);
traceprobe_finish_parse(&ctx);
return ret;
}
static int trace_eprobe_parse_filter(struct trace_eprobe *ep, int argc, const char *argv[])
{
struct event_filter *dummy = NULL;
int i, ret, len = 0;
char *p;
if (argc == 0) {
trace_probe_log_err(0, NO_EP_FILTER);
return -EINVAL;
}
/* Recover the filter string */
for (i = 0; i < argc; i++)
len += strlen(argv[i]) + 1;
ep->filter_str = kzalloc(len, GFP_KERNEL);
if (!ep->filter_str)
return -ENOMEM;
p = ep->filter_str;
for (i = 0; i < argc; i++) {
if (i)
ret = snprintf(p, len, " %s", argv[i]);
else
ret = snprintf(p, len, "%s", argv[i]);
p += ret;
len -= ret;
}
/*
* Ensure the filter string can be parsed correctly. Note, this
* filter string is for the original event, not for the eprobe.
*/
ret = create_event_filter(top_trace_array(), ep->event, ep->filter_str,
true, &dummy);
free_event_filter(dummy);
if (ret)
goto error;
return 0;
error:
kfree(ep->filter_str);
ep->filter_str = NULL;
return ret;
}
static int __trace_eprobe_create(int argc, const char *argv[])
{
/*
* Argument syntax:
* e[:[GRP/][ENAME]] SYSTEM.EVENT [FETCHARGS] [if FILTER]
* Fetch args (no space):
* <name>=$<field>[:TYPE]
*/
const char *event = NULL, *group = EPROBE_EVENT_SYSTEM;
const char *sys_event = NULL, *sys_name = NULL;
struct trace_event_call *event_call;
struct trace_eprobe *ep = NULL;
char buf1[MAX_EVENT_NAME_LEN];
char buf2[MAX_EVENT_NAME_LEN];
char gbuf[MAX_EVENT_NAME_LEN];
int ret = 0, filter_idx = 0;
int i, filter_cnt;
if (argc < 2 || argv[0][0] != 'e')
return -ECANCELED;
trace_probe_log_init("event_probe", argc, argv);
event = strchr(&argv[0][1], ':');
if (event) {
event++;
ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto parse_error;
}
trace_probe_log_set_index(1);
sys_event = argv[1];
ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
if (ret || !sys_event || !sys_name) {
trace_probe_log_err(0, NO_EVENT_INFO);
goto parse_error;
}
if (!event) {
strscpy(buf1, sys_event, MAX_EVENT_NAME_LEN);
event = buf1;
}
for (i = 2; i < argc; i++) {
if (!strcmp(argv[i], "if")) {
filter_idx = i + 1;
filter_cnt = argc - filter_idx;
argc = i;
break;
}
}
mutex_lock(&event_mutex);
event_call = find_and_get_event(sys_name, sys_event);
ep = alloc_event_probe(group, event, event_call, argc - 2);
mutex_unlock(&event_mutex);
if (IS_ERR(ep)) {
ret = PTR_ERR(ep);
if (ret == -ENODEV)
trace_probe_log_err(0, BAD_ATTACH_EVENT);
/* This must return -ENOMEM or missing event, else there is a bug */
WARN_ON_ONCE(ret != -ENOMEM && ret != -ENODEV);
ep = NULL;
goto error;
}
if (filter_idx) {
trace_probe_log_set_index(filter_idx);
ret = trace_eprobe_parse_filter(ep, filter_cnt, argv + filter_idx);
if (ret)
goto parse_error;
} else
ep->filter_str = NULL;
argc -= 2; argv += 2;
/* parse arguments */
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
trace_probe_log_set_index(i + 2);
ret = trace_eprobe_tp_update_arg(ep, argv, i);
if (ret)
goto error;
}
ret = traceprobe_set_print_fmt(&ep->tp, PROBE_PRINT_EVENT);
if (ret < 0)
goto error;
init_trace_eprobe_call(ep);
mutex_lock(&event_mutex);
ret = trace_probe_register_event_call(&ep->tp);
if (ret) {
if (ret == -EEXIST) {
trace_probe_log_set_index(0);
trace_probe_log_err(0, EVENT_EXIST);
}
mutex_unlock(&event_mutex);
goto error;
}
ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
mutex_unlock(&event_mutex);
return ret;
parse_error:
ret = -EINVAL;
error:
trace_event_probe_cleanup(ep);
return ret;
}
/*
* Register dynevent at core_initcall. This allows kernel to setup eprobe
* events in postcore_initcall without tracefs.
*/
static __init int trace_events_eprobe_init_early(void)
{
int err = 0;
err = dyn_event_register(&eprobe_dyn_event_ops);
if (err)
pr_warn("Could not register eprobe_dyn_event_ops\n");
return err;
}
core_initcall(trace_events_eprobe_init_early);