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tracing/kprobes: Use dyn_event framework for kprobe events 

Use dyn_event framework for kprobe events. This shows
kprobe events on "tracing/dynamic_events" file.

User can also define new events via tracing/dynamic_events.

Link: http://lkml.kernel.org/r/154140855646.17322.6619219995865980392.stgit@devbox

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2018-11-05 18:02:36 +09:00 committed by Steven Rostedt (VMware)
parent 5448d44c38
commit 6212dd2968
5 changed files with 210 additions and 148 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/trace/kprobetrace.rst
View File

@ -20,6 +20,9 @@ current_tracer. Instead of that, add probe points via
/sys/kernel/debug/tracing/kprobe_events, and enable it via
/sys/kernel/debug/tracing/events/kprobes/<EVENT>/enable.
You can also use /sys/kernel/debug/tracing/dynamic_events instead of
kprobe_events. That interface will provide unified access to other
dynamic events too.
Synopsis of kprobe_events
-------------------------

1
kernel/trace/Kconfig
View File

@ -461,6 +461,7 @@ config KPROBE_EVENTS
bool "Enable kprobes-based dynamic events"
select TRACING
select PROBE_EVENTS
select DYNAMIC_EVENTS
default y
help
This allows the user to add tracing events (similar to tracepoints)

325
kernel/trace/trace_kprobe.c
View File

@ -12,6 +12,7 @@
#include <linux/rculist.h>
#include <linux/error-injection.h>
#include "trace_dynevent.h"
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
@ -19,17 +20,51 @@
#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096
static int trace_kprobe_create(int argc, const char **argv);
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_kprobe_release(struct dyn_event *ev);
static bool trace_kprobe_is_busy(struct dyn_event *ev);
static bool trace_kprobe_match(const char *system, const char *event,
struct dyn_event *ev);
static struct dyn_event_operations trace_kprobe_ops = {
.create = trace_kprobe_create,
.show = trace_kprobe_show,
.is_busy = trace_kprobe_is_busy,
.free = trace_kprobe_release,
.match = trace_kprobe_match,
};
/**
* Kprobe event core functions
*/
struct trace_kprobe {
struct list_head list;
struct dyn_event devent;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long __percpu *nhit;
const char *symbol; /* symbol name */
struct trace_probe tp;
};
static bool is_trace_kprobe(struct dyn_event *ev)
{
return ev->ops == &trace_kprobe_ops;
}
static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
{
return container_of(ev, struct trace_kprobe, devent);
}
/**
* for_each_trace_kprobe - iterate over the trace_kprobe list
* @pos: the struct trace_kprobe * for each entry
* @dpos: the struct dyn_event * to use as a loop cursor
*/
#define for_each_trace_kprobe(pos, dpos) \
for_each_dyn_event(dpos) \
if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
#define SIZEOF_TRACE_KPROBE(n) \
(offsetof(struct trace_kprobe, tp.args) + \
(sizeof(struct probe_arg) * (n)))
@ -81,6 +116,22 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
return ret;
}
static bool trace_kprobe_is_busy(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
return trace_probe_is_enabled(&tk->tp);
}
static bool trace_kprobe_match(const char *system, const char *event,
struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
return strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
(!system || strcmp(tk->tp.call.class->system, system) == 0);
}
static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
{
unsigned long nhit = 0;
@ -128,9 +179,6 @@ bool trace_kprobe_error_injectable(struct trace_event_call *call)
static int register_kprobe_event(struct trace_kprobe *tk);
static int unregister_kprobe_event(struct trace_kprobe *tk);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);
static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
@ -192,7 +240,7 @@ static struct trace_kprobe *alloc_trace_kprobe(const char *group,
if (!tk->tp.class.system)
goto error;
INIT_LIST_HEAD(&tk->list);
dyn_event_init(&tk->devent, &trace_kprobe_ops);
INIT_LIST_HEAD(&tk->tp.files);
return tk;
error:
@ -207,6 +255,9 @@ static void free_trace_kprobe(struct trace_kprobe *tk)
{
int i;
if (!tk)
return;
for (i = 0; i < tk->tp.nr_args; i++)
traceprobe_free_probe_arg(&tk->tp.args[i]);
@ -220,9 +271,10 @@ static void free_trace_kprobe(struct trace_kprobe *tk)
static struct trace_kprobe *find_trace_kprobe(const char *event,
const char *group)
{
struct dyn_event *pos;
struct trace_kprobe *tk;
list_for_each_entry(tk, &probe_list, list)
for_each_trace_kprobe(tk, pos)
if (strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
strcmp(tk->tp.call.class->system, group) == 0)
return tk;
@ -321,7 +373,7 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
* created with perf_event_open. We don't need to wait for these
* trace_kprobes
*/
if (list_empty(&tk->list))
if (list_empty(&tk->devent.list))
wait = 0;
out:
if (wait) {
@ -419,7 +471,7 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk)
}
}
/* Unregister a trace_probe and probe_event: call with locking probe_lock */
/* Unregister a trace_probe and probe_event */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* Enabled event can not be unregistered */
@ -431,7 +483,7 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk)
return -EBUSY;
__unregister_trace_kprobe(tk);
list_del(&tk->list);
dyn_event_remove(&tk->devent);
return 0;
}
@ -442,7 +494,7 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
struct trace_kprobe *old_tk;
int ret;
mutex_lock(&probe_lock);
mutex_lock(&event_mutex);
/* Delete old (same name) event if exist */
old_tk = find_trace_kprobe(trace_event_name(&tk->tp.call),
@ -471,10 +523,10 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
if (ret < 0)
unregister_kprobe_event(tk);
else
list_add_tail(&tk->list, &probe_list);
dyn_event_add(&tk->devent);
end:
mutex_unlock(&probe_lock);
mutex_unlock(&event_mutex);
return ret;
}
@ -483,6 +535,7 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
{
struct module *mod = data;
struct dyn_event *pos;
struct trace_kprobe *tk;
int ret;
@ -490,8 +543,8 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
return NOTIFY_DONE;
/* Update probes on coming module */
mutex_lock(&probe_lock);
list_for_each_entry(tk, &probe_list, list) {
mutex_lock(&event_mutex);
for_each_trace_kprobe(tk, pos) {
if (trace_kprobe_within_module(tk, mod)) {
/* Don't need to check busy - this should have gone. */
__unregister_trace_kprobe(tk);
@ -502,7 +555,7 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
mod->name, ret);
}
}
mutex_unlock(&probe_lock);
mutex_unlock(&event_mutex);
return NOTIFY_DONE;
}
@ -520,7 +573,7 @@ static inline void sanitize_event_name(char *name)
*name = '_';
}
static int create_trace_kprobe(int argc, char **argv)
static int trace_kprobe_create(int argc, const char *argv[])
{
/*
* Argument syntax:
@ -544,9 +597,10 @@ static int create_trace_kprobe(int argc, char **argv)
* FETCHARG:TYPE : use TYPE instead of unsigned long.
*/
struct trace_kprobe *tk;
int i, ret = 0;
bool is_return = false, is_delete = false;
char *symbol = NULL, *event = NULL, *group = NULL;
int i, len, ret = 0;
bool is_return = false;
char *symbol = NULL, *tmp = NULL;
const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
int maxactive = 0;
long offset = 0;
void *addr = NULL;
@ -554,26 +608,26 @@ static int create_trace_kprobe(int argc, char **argv)
unsigned int flags = TPARG_FL_KERNEL;
/* argc must be >= 1 */
if (argv[0][0] == 'p')
is_return = false;
else if (argv[0][0] == 'r') {
if (argv[0][0] == 'r') {
is_return = true;
flags |= TPARG_FL_RETURN;
} else if (argv[0][0] == '-')
is_delete = true;
else {
pr_info("Probe definition must be started with 'p', 'r' or"
" '-'.\n");
return -EINVAL;
}
} else if (argv[0][0] != 'p' || argc < 2)
return -ECANCELED;
event = strchr(&argv[0][1], ':');
if (event) {
event[0] = '\0';
if (event)
event++;
}
if (is_return && isdigit(argv[0][1])) {
ret = kstrtouint(&argv[0][1], 0, &maxactive);
if (event)
len = event - &argv[0][1] - 1;
else
len = strlen(&argv[0][1]);
if (len > MAX_EVENT_NAME_LEN - 1)
return -E2BIG;
memcpy(buf, &argv[0][1], len);
buf[len] = '\0';
ret = kstrtouint(buf, 0, &maxactive);
if (ret) {
pr_info("Failed to parse maxactive.\n");
return ret;
@ -588,74 +642,37 @@ static int create_trace_kprobe(int argc, char **argv)
}
}
if (event) {
char *slash;
slash = strchr(event, '/');
if (slash) {
group = event;
event = slash + 1;
slash[0] = '\0';
if (strlen(group) == 0) {
pr_info("Group name is not specified\n");
return -EINVAL;
}
}
if (strlen(event) == 0) {
pr_info("Event name is not specified\n");
return -EINVAL;
}
}
if (!group)
group = KPROBE_EVENT_SYSTEM;
if (is_delete) {
if (!event) {
pr_info("Delete command needs an event name.\n");
return -EINVAL;
}
mutex_lock(&probe_lock);
tk = find_trace_kprobe(event, group);
if (!tk) {
mutex_unlock(&probe_lock);
pr_info("Event %s/%s doesn't exist.\n", group, event);
return -ENOENT;
}
/* delete an event */
ret = unregister_trace_kprobe(tk);
if (ret == 0)
free_trace_kprobe(tk);
mutex_unlock(&probe_lock);
return ret;
}
if (argc < 2) {
pr_info("Probe point is not specified.\n");
return -EINVAL;
}
/* try to parse an address. if that fails, try to read the
* input as a symbol. */
if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
/* Check whether uprobe event specified */
if (strchr(argv[1], '/') && strchr(argv[1], ':'))
return -ECANCELED;
/* a symbol specified */
symbol = argv[1];
symbol = kstrdup(argv[1], GFP_KERNEL);
if (!symbol)
return -ENOMEM;
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret || offset < 0 || offset > UINT_MAX) {
pr_info("Failed to parse either an address or a symbol.\n");
return ret;
goto out;
}
if (kprobe_on_func_entry(NULL, symbol, offset))
flags |= TPARG_FL_FENTRY;
if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {
pr_info("Given offset is not valid for return probe.\n");
return -EINVAL;
ret = -EINVAL;
goto out;
}
}
argc -= 2; argv += 2;
/* setup a probe */
if (!event) {
if (event) {
ret = traceprobe_parse_event_name(&event, &group, buf);
if (ret)
goto out;
} else {
/* Make a new event name */
if (symbol)
snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
@ -666,17 +683,27 @@ static int create_trace_kprobe(int argc, char **argv)
sanitize_event_name(buf);
event = buf;
}
/* setup a probe */
tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
argc, is_return);
if (IS_ERR(tk)) {
pr_info("Failed to allocate trace_probe.(%d)\n",
(int)PTR_ERR(tk));
return PTR_ERR(tk);
ret = PTR_ERR(tk);
goto out;
}
/* parse arguments */
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
ret = traceprobe_parse_probe_arg(&tk->tp, i, argv[i], flags);
tmp = kstrdup(argv[i], GFP_KERNEL);
if (!tmp) {
ret = -ENOMEM;
goto error;
}
ret = traceprobe_parse_probe_arg(&tk->tp, i, tmp, flags);
kfree(tmp);
if (ret)
goto error;
}
@ -684,60 +711,39 @@ static int create_trace_kprobe(int argc, char **argv)
ret = register_trace_kprobe(tk);
if (ret)
goto error;
return 0;
out:
kfree(symbol);
return ret;
error:
free_trace_kprobe(tk);
return ret;
goto out;
}
static int release_all_trace_kprobes(void)
static int create_or_delete_trace_kprobe(int argc, char **argv)
{
struct trace_kprobe *tk;
int ret = 0;
int ret;
mutex_lock(&probe_lock);
/* Ensure no probe is in use. */
list_for_each_entry(tk, &probe_list, list)
if (trace_probe_is_enabled(&tk->tp)) {
ret = -EBUSY;
goto end;
}
/* TODO: Use batch unregistration */
while (!list_empty(&probe_list)) {
tk = list_entry(probe_list.next, struct trace_kprobe, list);
ret = unregister_trace_kprobe(tk);
if (ret)
goto end;
if (argv[0][0] == '-')
return dyn_event_release(argc, argv, &trace_kprobe_ops);
ret = trace_kprobe_create(argc, (const char **)argv);
return ret == -ECANCELED ? -EINVAL : ret;
}
static int trace_kprobe_release(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
int ret = unregister_trace_kprobe(tk);
if (!ret)
free_trace_kprobe(tk);
}
end:
mutex_unlock(&probe_lock);
return ret;
}
/* Probes listing interfaces */
static void *probes_seq_start(struct seq_file *m, loff_t *pos)
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
{
mutex_lock(&probe_lock);
return seq_list_start(&probe_list, *pos);
}
static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &probe_list, pos);
}
static void probes_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&probe_lock);
}
static int probes_seq_show(struct seq_file *m, void *v)
{
struct trace_kprobe *tk = v;
struct trace_kprobe *tk = to_trace_kprobe(ev);
int i;
seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
@ -759,10 +765,20 @@ static int probes_seq_show(struct seq_file *m, void *v)
return 0;
}
static int probes_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
if (!is_trace_kprobe(ev))
return 0;
return trace_kprobe_show(m, ev);
}
static const struct seq_operations probes_seq_op = {
.start = probes_seq_start,
.next = probes_seq_next,
.stop = probes_seq_stop,
.start = dyn_event_seq_start,
.next = dyn_event_seq_next,
.stop = dyn_event_seq_stop,
.show = probes_seq_show
};
@ -771,7 +787,7 @@ static int probes_open(struct inode *inode, struct file *file)
int ret;
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = release_all_trace_kprobes();
ret = dyn_events_release_all(&trace_kprobe_ops);
if (ret < 0)
return ret;
}
@ -783,7 +799,7 @@ static ssize_t probes_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
return trace_parse_run_command(file, buffer, count, ppos,
create_trace_kprobe);
create_or_delete_trace_kprobe);
}
static const struct file_operations kprobe_events_ops = {
@ -798,8 +814,13 @@ static const struct file_operations kprobe_events_ops = {
/* Probes profiling interfaces */
static int probes_profile_seq_show(struct seq_file *m, void *v)
{
struct trace_kprobe *tk = v;
struct dyn_event *ev = v;
struct trace_kprobe *tk;
if (!is_trace_kprobe(ev))
return 0;
tk = to_trace_kprobe(ev);
seq_printf(m, " %-44s %15lu %15lu\n",
trace_event_name(&tk->tp.call),
trace_kprobe_nhit(tk),
@ -809,9 +830,9 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
}
static const struct seq_operations profile_seq_op = {
.start = probes_seq_start,
.next = probes_seq_next,
.stop = probes_seq_stop,
.start = dyn_event_seq_start,
.next = dyn_event_seq_next,
.stop = dyn_event_seq_stop,
.show = probes_profile_seq_show
};
@ -1332,7 +1353,7 @@ static int register_kprobe_event(struct trace_kprobe *tk)
kfree(call->print_fmt);
return -ENODEV;
}
ret = trace_add_event_call(call);
ret = trace_add_event_call_nolock(call);
if (ret) {
pr_info("Failed to register kprobe event: %s\n",
trace_event_name(call));
@ -1347,7 +1368,7 @@ static int unregister_kprobe_event(struct trace_kprobe *tk)
int ret;
/* tp->event is unregistered in trace_remove_event_call() */
ret = trace_remove_event_call(&tk->tp.call);
ret = trace_remove_event_call_nolock(&tk->tp.call);
if (!ret)
kfree(tk->tp.call.print_fmt);
return ret;
@ -1364,7 +1385,7 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
char *event;
/*
* local trace_kprobes are not added to probe_list, so they are never
* local trace_kprobes are not added to dyn_event, so they are never
* searched in find_trace_kprobe(). Therefore, there is no concern of
* duplicated name here.
*/
@ -1422,6 +1443,11 @@ static __init int init_kprobe_trace(void)
{
struct dentry *d_tracer;
struct dentry *entry;
int ret;
ret = dyn_event_register(&trace_kprobe_ops);
if (ret)
return ret;
if (register_module_notifier(&trace_kprobe_module_nb))
return -EINVAL;
@ -1479,9 +1505,8 @@ static __init int kprobe_trace_self_tests_init(void)
pr_info("Testing kprobe tracing: ");
ret = trace_run_command("p:testprobe kprobe_trace_selftest_target "
"$stack $stack0 +0($stack)",
create_trace_kprobe);
ret = trace_run_command("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)",
create_or_delete_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on probing function entry.\n");
warn++;
@ -1501,8 +1526,8 @@ static __init int kprobe_trace_self_tests_init(void)
}
}
ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target "
"$retval", create_trace_kprobe);
ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target $retval",
create_or_delete_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on probing function return.\n");
warn++;
@ -1572,20 +1597,24 @@ static __init int kprobe_trace_self_tests_init(void)
disable_trace_kprobe(tk, file);
}
ret = trace_run_command("-:testprobe", create_trace_kprobe);
ret = trace_run_command("-:testprobe", create_or_delete_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
ret = trace_run_command("-:testprobe2", create_trace_kprobe);
ret = trace_run_command("-:testprobe2", create_or_delete_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
end:
release_all_trace_kprobes();
ret = dyn_events_release_all(&trace_kprobe_ops);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on cleaning up probes.\n");
warn++;
}
/*
* Wait for the optimizer work to finish. Otherwise it might fiddle
* with probes in already freed __init text.

27
kernel/trace/trace_probe.c
View File

@ -154,6 +154,33 @@ int traceprobe_split_symbol_offset(char *symbol, long *offset)
return 0;
}
/* @buf must has MAX_EVENT_NAME_LEN size */
int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
char *buf)
{
const char *slash, *event = *pevent;
slash = strchr(event, '/');
if (slash) {
if (slash == event) {
pr_info("Group name is not specified\n");
return -EINVAL;
}
if (slash - event + 1 > MAX_EVENT_NAME_LEN) {
pr_info("Group name is too long\n");
return -E2BIG;
}
strlcpy(buf, event, slash - event + 1);
*pgroup = buf;
*pevent = slash + 1;
}
if (strlen(event) == 0) {
pr_info("Event name is not specified\n");
return -EINVAL;
}
return 0;
}
#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
static int parse_probe_vars(char *arg, const struct fetch_type *t,

2
kernel/trace/trace_probe.h
View File

@ -279,6 +279,8 @@ extern int traceprobe_update_arg(struct probe_arg *arg);
extern void traceprobe_free_probe_arg(struct probe_arg *arg);
extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
extern int traceprobe_parse_event_name(const char **pevent,
const char **pgroup, char *buf);
extern int traceprobe_set_print_fmt(struct trace_probe *tp, bool is_return);