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Message-Id: <20200329184318.079639822@goodmis.org>
Date: Sun, 29 Mar 2020 14:43:10 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [for-next][PATCH 18/21] tracing: Create set_event_notrace_pid to not trace tasks
From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
There's currently a way to select a task that should only have its events
traced, but there's no way to select a task not to have itsevents traced.
Add a set_event_notrace_pid file that acts the same as set_event_pid (and is
also affected by event-fork), but the task pids in this file will not be
traced even if they are listed in the set_event_pid file. This makes it easy
for tools like trace-cmd to "hide" itself from beint traced by events when
it is recording other tasks.
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
kernel/trace/ftrace.c | 11 +-
kernel/trace/trace.h | 25 ++++
kernel/trace/trace_events.c | 280 ++++++++++++++++++++++++++++--------
3 files changed, 244 insertions(+), 72 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7239d9acd09f..0bb62e64280c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6987,11 +6987,6 @@ void ftrace_pid_follow_fork(struct trace_array *tr, bool enable)
}
}
-enum {
- TRACE_PIDS = BIT(0),
- TRACE_NO_PIDS = BIT(1),
-};
-
static void clear_ftrace_pids(struct trace_array *tr, int type)
{
struct trace_pid_list *pid_list;
@@ -7004,13 +6999,11 @@ static void clear_ftrace_pids(struct trace_array *tr, int type)
lockdep_is_held(&ftrace_lock));
/* Make sure there's something to do */
- if (!(((type & TRACE_PIDS) && pid_list) ||
- ((type & TRACE_NO_PIDS) && no_pid_list)))
+ if (!pid_type_enabled(type, pid_list, no_pid_list))
return;
/* See if the pids still need to be checked after this */
- if (!((!(type & TRACE_PIDS) && pid_list) ||
- (!(type & TRACE_NO_PIDS) && no_pid_list))) {
+ if (!still_need_pid_events(type, pid_list, no_pid_list)) {
unregister_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
for_each_possible_cpu(cpu)
per_cpu_ptr(tr->array_buffer.data, cpu)->ftrace_ignore_pid = FTRACE_PID_TRACE;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6b5ff5adb4ad..4eb1d004d5f2 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -207,6 +207,30 @@ struct trace_pid_list {
unsigned long *pids;
};
+enum {
+ TRACE_PIDS = BIT(0),
+ TRACE_NO_PIDS = BIT(1),
+};
+
+static inline bool pid_type_enabled(int type, struct trace_pid_list *pid_list,
+ struct trace_pid_list *no_pid_list)
+{
+ /* Return true if the pid list in type has pids */
+ return ((type & TRACE_PIDS) && pid_list) ||
+ ((type & TRACE_NO_PIDS) && no_pid_list);
+}
+
+static inline bool still_need_pid_events(int type, struct trace_pid_list *pid_list,
+ struct trace_pid_list *no_pid_list)
+{
+ /*
+ * Turning off what is in @type, return true if the "other"
+ * pid list, still has pids in it.
+ */
+ return (!(type & TRACE_PIDS) && pid_list) ||
+ (!(type & TRACE_NO_PIDS) && no_pid_list);
+}
+
typedef bool (*cond_update_fn_t)(struct trace_array *tr, void *cond_data);
/**
@@ -285,6 +309,7 @@ struct trace_array {
#endif
#endif
struct trace_pid_list __rcu *filtered_pids;
+ struct trace_pid_list __rcu *filtered_no_pids;
/*
* max_lock is used to protect the swapping of buffers
* when taking a max snapshot. The buffers themselves are
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c196d0dc5871..242f59e7f17d 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -232,10 +232,13 @@ bool trace_event_ignore_this_pid(struct trace_event_file *trace_file)
{
struct trace_array *tr = trace_file->tr;
struct trace_array_cpu *data;
+ struct trace_pid_list *no_pid_list;
struct trace_pid_list *pid_list;
pid_list = rcu_dereference_raw(tr->filtered_pids);
- if (!pid_list)
+ no_pid_list = rcu_dereference_raw(tr->filtered_no_pids);
+
+ if (!pid_list && !no_pid_list)
return false;
data = this_cpu_ptr(tr->array_buffer.data);
@@ -510,6 +513,9 @@ event_filter_pid_sched_process_exit(void *data, struct task_struct *task)
pid_list = rcu_dereference_raw(tr->filtered_pids);
trace_filter_add_remove_task(pid_list, NULL, task);
+
+ pid_list = rcu_dereference_raw(tr->filtered_no_pids);
+ trace_filter_add_remove_task(pid_list, NULL, task);
}
static void
@@ -522,6 +528,9 @@ event_filter_pid_sched_process_fork(void *data,
pid_list = rcu_dereference_sched(tr->filtered_pids);
trace_filter_add_remove_task(pid_list, self, task);
+
+ pid_list = rcu_dereference_sched(tr->filtered_no_pids);
+ trace_filter_add_remove_task(pid_list, self, task);
}
void trace_event_follow_fork(struct trace_array *tr, bool enable)
@@ -544,13 +553,23 @@ event_filter_pid_sched_switch_probe_pre(void *data, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
struct trace_array *tr = data;
+ struct trace_pid_list *no_pid_list;
struct trace_pid_list *pid_list;
+ bool ret;
pid_list = rcu_dereference_sched(tr->filtered_pids);
+ no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);
- this_cpu_write(tr->array_buffer.data->ignore_pid,
- trace_ignore_this_task(pid_list, NULL, prev) &&
- trace_ignore_this_task(pid_list, NULL, next));
+ /*
+ * Sched switch is funny, as we only want to ignore it
+ * in the notrace case if both prev and next should be ignored.
+ */
+ ret = trace_ignore_this_task(NULL, no_pid_list, prev) &&
+ trace_ignore_this_task(NULL, no_pid_list, next);
+
+ this_cpu_write(tr->array_buffer.data->ignore_pid, ret ||
+ (trace_ignore_this_task(pid_list, NULL, prev) &&
+ trace_ignore_this_task(pid_list, NULL, next)));
}
static void
@@ -558,18 +577,21 @@ event_filter_pid_sched_switch_probe_post(void *data, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
struct trace_array *tr = data;
+ struct trace_pid_list *no_pid_list;
struct trace_pid_list *pid_list;
pid_list = rcu_dereference_sched(tr->filtered_pids);
+ no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);
this_cpu_write(tr->array_buffer.data->ignore_pid,
- trace_ignore_this_task(pid_list, NULL, next));
+ trace_ignore_this_task(pid_list, no_pid_list, next));
}
static void
event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
{
struct trace_array *tr = data;
+ struct trace_pid_list *no_pid_list;
struct trace_pid_list *pid_list;
/* Nothing to do if we are already tracing */
@@ -577,15 +599,17 @@ event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
return;
pid_list = rcu_dereference_sched(tr->filtered_pids);
+ no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);
this_cpu_write(tr->array_buffer.data->ignore_pid,
- trace_ignore_this_task(pid_list, NULL, task));
+ trace_ignore_this_task(pid_list, no_pid_list, task));
}
static void
event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
{
struct trace_array *tr = data;
+ struct trace_pid_list *no_pid_list;
struct trace_pid_list *pid_list;
/* Nothing to do if we are not tracing */
@@ -593,23 +617,15 @@ event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
return;
pid_list = rcu_dereference_sched(tr->filtered_pids);
+ no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);
/* Set tracing if current is enabled */
this_cpu_write(tr->array_buffer.data->ignore_pid,
- trace_ignore_this_task(pid_list, NULL, current));
+ trace_ignore_this_task(pid_list, no_pid_list, current));
}
-static void __ftrace_clear_event_pids(struct trace_array *tr)
+static void unregister_pid_events(struct trace_array *tr)
{
- struct trace_pid_list *pid_list;
- struct trace_event_file *file;
- int cpu;
-
- pid_list = rcu_dereference_protected(tr->filtered_pids,
- lockdep_is_held(&event_mutex));
- if (!pid_list)
- return;
-
unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_pre, tr);
unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_post, tr);
@@ -621,26 +637,55 @@ static void __ftrace_clear_event_pids(struct trace_array *tr)
unregister_trace_sched_waking(event_filter_pid_sched_wakeup_probe_pre, tr);
unregister_trace_sched_waking(event_filter_pid_sched_wakeup_probe_post, tr);
+}
- list_for_each_entry(file, &tr->events, list) {
- clear_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
+static void __ftrace_clear_event_pids(struct trace_array *tr, int type)
+{
+ struct trace_pid_list *pid_list;
+ struct trace_pid_list *no_pid_list;
+ struct trace_event_file *file;
+ int cpu;
+
+ pid_list = rcu_dereference_protected(tr->filtered_pids,
+ lockdep_is_held(&event_mutex));
+ no_pid_list = rcu_dereference_protected(tr->filtered_no_pids,
+ lockdep_is_held(&event_mutex));
+
+ /* Make sure there's something to do */
+ if (!pid_type_enabled(type, pid_list, no_pid_list))
+ return;
+
+ if (!still_need_pid_events(type, pid_list, no_pid_list)) {
+ unregister_pid_events(tr);
+
+ list_for_each_entry(file, &tr->events, list) {
+ clear_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
+ }
+
+ for_each_possible_cpu(cpu)
+ per_cpu_ptr(tr->array_buffer.data, cpu)->ignore_pid = false;
}
- for_each_possible_cpu(cpu)
- per_cpu_ptr(tr->array_buffer.data, cpu)->ignore_pid = false;
+ if (type & TRACE_PIDS)
+ rcu_assign_pointer(tr->filtered_pids, NULL);
- rcu_assign_pointer(tr->filtered_pids, NULL);
+ if (type & TRACE_NO_PIDS)
+ rcu_assign_pointer(tr->filtered_no_pids, NULL);
/* Wait till all users are no longer using pid filtering */
tracepoint_synchronize_unregister();
- trace_free_pid_list(pid_list);
+ if ((type & TRACE_PIDS) && pid_list)
+ trace_free_pid_list(pid_list);
+
+ if ((type & TRACE_NO_PIDS) && no_pid_list)
+ trace_free_pid_list(no_pid_list);
}
-static void ftrace_clear_event_pids(struct trace_array *tr)
+static void ftrace_clear_event_pids(struct trace_array *tr, int type)
{
mutex_lock(&event_mutex);
- __ftrace_clear_event_pids(tr);
+ __ftrace_clear_event_pids(tr, type);
mutex_unlock(&event_mutex);
}
@@ -1013,15 +1058,32 @@ static void t_stop(struct seq_file *m, void *p)
}
static void *
-p_next(struct seq_file *m, void *v, loff_t *pos)
+__next(struct seq_file *m, void *v, loff_t *pos, int type)
{
struct trace_array *tr = m->private;
- struct trace_pid_list *pid_list = rcu_dereference_sched(tr->filtered_pids);
+ struct trace_pid_list *pid_list;
+
+ if (type == TRACE_PIDS)
+ pid_list = rcu_dereference_sched(tr->filtered_pids);
+ else
+ pid_list = rcu_dereference_sched(tr->filtered_no_pids);
return trace_pid_next(pid_list, v, pos);
}
-static void *p_start(struct seq_file *m, loff_t *pos)
+static void *
+p_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ return __next(m, v, pos, TRACE_PIDS);
+}
+
+static void *
+np_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ return __next(m, v, pos, TRACE_NO_PIDS);
+}
+
+static void *__start(struct seq_file *m, loff_t *pos, int type)
__acquires(RCU)
{
struct trace_pid_list *pid_list;
@@ -1036,7 +1098,10 @@ static void *p_start(struct seq_file *m, loff_t *pos)
mutex_lock(&event_mutex);
rcu_read_lock_sched();
- pid_list = rcu_dereference_sched(tr->filtered_pids);
+ if (type == TRACE_PIDS)
+ pid_list = rcu_dereference_sched(tr->filtered_pids);
+ else
+ pid_list = rcu_dereference_sched(tr->filtered_no_pids);
if (!pid_list)
return NULL;
@@ -1044,6 +1109,18 @@ static void *p_start(struct seq_file *m, loff_t *pos)
return trace_pid_start(pid_list, pos);
}
+static void *p_start(struct seq_file *m, loff_t *pos)
+ __acquires(RCU)
+{
+ return __start(m, pos, TRACE_PIDS);
+}
+
+static void *np_start(struct seq_file *m, loff_t *pos)
+ __acquires(RCU)
+{
+ return __start(m, pos, TRACE_NO_PIDS);
+}
+
static void p_stop(struct seq_file *m, void *p)
__releases(RCU)
{
@@ -1588,6 +1665,7 @@ static void ignore_task_cpu(void *data)
{
struct trace_array *tr = data;
struct trace_pid_list *pid_list;
+ struct trace_pid_list *no_pid_list;
/*
* This function is called by on_each_cpu() while the
@@ -1595,18 +1673,50 @@ static void ignore_task_cpu(void *data)
*/
pid_list = rcu_dereference_protected(tr->filtered_pids,
mutex_is_locked(&event_mutex));
+ no_pid_list = rcu_dereference_protected(tr->filtered_no_pids,
+ mutex_is_locked(&event_mutex));
this_cpu_write(tr->array_buffer.data->ignore_pid,
- trace_ignore_this_task(pid_list, NULL, current));
+ trace_ignore_this_task(pid_list, no_pid_list, current));
+}
+
+static void register_pid_events(struct trace_array *tr)
+{
+ /*
+ * Register a probe that is called before all other probes
+ * to set ignore_pid if next or prev do not match.
+ * Register a probe this is called after all other probes
+ * to only keep ignore_pid set if next pid matches.
+ */
+ register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_pre,
+ tr, INT_MAX);
+ register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_post,
+ tr, 0);
+
+ register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre,
+ tr, INT_MAX);
+ register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,
+ tr, 0);
+
+ register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_pre,
+ tr, INT_MAX);
+ register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_post,
+ tr, 0);
+
+ register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_pre,
+ tr, INT_MAX);
+ register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_post,
+ tr, 0);
}
static ssize_t
-ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *ppos)
+event_pid_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos, int type)
{
struct seq_file *m = filp->private_data;
struct trace_array *tr = m->private;
struct trace_pid_list *filtered_pids = NULL;
+ struct trace_pid_list *other_pids = NULL;
struct trace_pid_list *pid_list;
struct trace_event_file *file;
ssize_t ret;
@@ -1620,14 +1730,26 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
mutex_lock(&event_mutex);
- filtered_pids = rcu_dereference_protected(tr->filtered_pids,
- lockdep_is_held(&event_mutex));
+ if (type == TRACE_PIDS) {
+ filtered_pids = rcu_dereference_protected(tr->filtered_pids,
+ lockdep_is_held(&event_mutex));
+ other_pids = rcu_dereference_protected(tr->filtered_no_pids,
+ lockdep_is_held(&event_mutex));
+ } else {
+ filtered_pids = rcu_dereference_protected(tr->filtered_no_pids,
+ lockdep_is_held(&event_mutex));
+ other_pids = rcu_dereference_protected(tr->filtered_pids,
+ lockdep_is_held(&event_mutex));
+ }
ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
if (ret < 0)
goto out;
- rcu_assign_pointer(tr->filtered_pids, pid_list);
+ if (type == TRACE_PIDS)
+ rcu_assign_pointer(tr->filtered_pids, pid_list);
+ else
+ rcu_assign_pointer(tr->filtered_no_pids, pid_list);
list_for_each_entry(file, &tr->events, list) {
set_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
@@ -1636,32 +1758,8 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
if (filtered_pids) {
tracepoint_synchronize_unregister();
trace_free_pid_list(filtered_pids);
- } else if (pid_list) {
- /*
- * Register a probe that is called before all other probes
- * to set ignore_pid if next or prev do not match.
- * Register a probe this is called after all other probes
- * to only keep ignore_pid set if next pid matches.
- */
- register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_pre,
- tr, INT_MAX);
- register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_post,
- tr, 0);
-
- register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre,
- tr, INT_MAX);
- register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,
- tr, 0);
-
- register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_pre,
- tr, INT_MAX);
- register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_post,
- tr, 0);
-
- register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_pre,
- tr, INT_MAX);
- register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_post,
- tr, 0);
+ } else if (pid_list && !other_pids) {
+ register_pid_events(tr);
}
/*
@@ -1680,9 +1778,24 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
return ret;
}
+static ssize_t
+ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ return event_pid_write(filp, ubuf, cnt, ppos, TRACE_PIDS);
+}
+
+static ssize_t
+ftrace_event_npid_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ return event_pid_write(filp, ubuf, cnt, ppos, TRACE_NO_PIDS);
+}
+
static int ftrace_event_avail_open(struct inode *inode, struct file *file);
static int ftrace_event_set_open(struct inode *inode, struct file *file);
static int ftrace_event_set_pid_open(struct inode *inode, struct file *file);
+static int ftrace_event_set_npid_open(struct inode *inode, struct file *file);
static int ftrace_event_release(struct inode *inode, struct file *file);
static const struct seq_operations show_event_seq_ops = {
@@ -1706,6 +1819,13 @@ static const struct seq_operations show_set_pid_seq_ops = {
.stop = p_stop,
};
+static const struct seq_operations show_set_no_pid_seq_ops = {
+ .start = np_start,
+ .next = np_next,
+ .show = trace_pid_show,
+ .stop = p_stop,
+};
+
static const struct file_operations ftrace_avail_fops = {
.open = ftrace_event_avail_open,
.read = seq_read,
@@ -1729,6 +1849,14 @@ static const struct file_operations ftrace_set_event_pid_fops = {
.release = ftrace_event_release,
};
+static const struct file_operations ftrace_set_event_notrace_pid_fops = {
+ .open = ftrace_event_set_npid_open,
+ .read = seq_read,
+ .write = ftrace_event_npid_write,
+ .llseek = seq_lseek,
+ .release = ftrace_event_release,
+};
+
static const struct file_operations ftrace_enable_fops = {
.open = tracing_open_generic,
.read = event_enable_read,
@@ -1858,7 +1986,28 @@ ftrace_event_set_pid_open(struct inode *inode, struct file *file)
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
- ftrace_clear_event_pids(tr);
+ ftrace_clear_event_pids(tr, TRACE_PIDS);
+
+ ret = ftrace_event_open(inode, file, seq_ops);
+ if (ret < 0)
+ trace_array_put(tr);
+ return ret;
+}
+
+static int
+ftrace_event_set_npid_open(struct inode *inode, struct file *file)
+{
+ const struct seq_operations *seq_ops = &show_set_no_pid_seq_ops;
+ struct trace_array *tr = inode->i_private;
+ int ret;
+
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
+
+ if ((file->f_mode & FMODE_WRITE) &&
+ (file->f_flags & O_TRUNC))
+ ftrace_clear_event_pids(tr, TRACE_NO_PIDS);
ret = ftrace_event_open(inode, file, seq_ops);
if (ret < 0)
@@ -3075,6 +3224,11 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
if (!entry)
pr_warn("Could not create tracefs 'set_event_pid' entry\n");
+ entry = tracefs_create_file("set_event_notrace_pid", 0644, parent,
+ tr, &ftrace_set_event_notrace_pid_fops);
+ if (!entry)
+ pr_warn("Could not create tracefs 'set_event_notrace_pid' entry\n");
+
/* ring buffer internal formats */
entry = trace_create_file("header_page", 0444, d_events,
ring_buffer_print_page_header,
@@ -3158,7 +3312,7 @@ int event_trace_del_tracer(struct trace_array *tr)
clear_event_triggers(tr);
/* Clear the pid list */
- __ftrace_clear_event_pids(tr);
+ __ftrace_clear_event_pids(tr, TRACE_PIDS | TRACE_NO_PIDS);
/* Disable any running events */
__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);
--
2.25.1
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