diff options
author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-19 23:19:06 -0400 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-27 16:39:02 -0400 |
commit | b3b1e6ededa4337940adba6cf06e8351056e3097 (patch) | |
tree | d316c05b89cf064f9221aaac8afb0c9b259f6e8a /kernel | |
parent | 717e3f5ebc823e5ecfdd15155b0fd81af9fc58d6 (diff) | |
download | linux-b3b1e6ededa4337940adba6cf06e8351056e3097.tar.bz2 |
ftrace: Create set_ftrace_notrace_pid to not trace tasks
There's currently a way to select a task that should only be traced by
functions, but there's no way to select a task not to be traced by the
function tracer. Add a set_ftrace_notrace_pid file that acts the same as
set_ftrace_pid (and is also affected by function-fork), but the task pids in
this file will not be traced even if they are listed in the set_ftrace_pid
file. This makes it easy for tools like trace-cmd to "hide" itself from the
function tracer when it is recording other tasks.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/trace/ftrace.c | 181 | ||||
-rw-r--r-- | kernel/trace/trace.c | 20 | ||||
-rw-r--r-- | kernel/trace/trace.h | 2 | ||||
-rw-r--r-- | kernel/trace/trace_events.c | 12 |
4 files changed, 180 insertions, 35 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 34ae736cb1f8..7239d9acd09f 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -102,7 +102,7 @@ static bool ftrace_pids_enabled(struct ftrace_ops *ops) tr = ops->private; - return tr->function_pids != NULL; + return tr->function_pids != NULL || tr->function_no_pids != NULL; } static void ftrace_update_trampoline(struct ftrace_ops *ops); @@ -6931,10 +6931,12 @@ ftrace_filter_pid_sched_switch_probe(void *data, bool preempt, { struct trace_array *tr = data; struct trace_pid_list *pid_list; + struct trace_pid_list *no_pid_list; pid_list = rcu_dereference_sched(tr->function_pids); + no_pid_list = rcu_dereference_sched(tr->function_no_pids); - if (trace_ignore_this_task(pid_list, next)) + if (trace_ignore_this_task(pid_list, no_pid_list, next)) this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid, FTRACE_PID_IGNORE); else @@ -6952,6 +6954,9 @@ ftrace_pid_follow_sched_process_fork(void *data, pid_list = rcu_dereference_sched(tr->function_pids); trace_filter_add_remove_task(pid_list, self, task); + + pid_list = rcu_dereference_sched(tr->function_no_pids); + trace_filter_add_remove_task(pid_list, self, task); } static void @@ -6962,6 +6967,9 @@ ftrace_pid_follow_sched_process_exit(void *data, struct task_struct *task) pid_list = rcu_dereference_sched(tr->function_pids); trace_filter_add_remove_task(pid_list, NULL, task); + + pid_list = rcu_dereference_sched(tr->function_no_pids); + trace_filter_add_remove_task(pid_list, NULL, task); } void ftrace_pid_follow_fork(struct trace_array *tr, bool enable) @@ -6979,42 +6987,64 @@ void ftrace_pid_follow_fork(struct trace_array *tr, bool enable) } } -static void clear_ftrace_pids(struct trace_array *tr) +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; + struct trace_pid_list *no_pid_list; int cpu; pid_list = rcu_dereference_protected(tr->function_pids, lockdep_is_held(&ftrace_lock)); - if (!pid_list) + no_pid_list = rcu_dereference_protected(tr->function_no_pids, + 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))) return; - unregister_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr); + /* See if the pids still need to be checked after this */ + if (!((!(type & TRACE_PIDS) && pid_list) || + (!(type & TRACE_NO_PIDS) && 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; + } - for_each_possible_cpu(cpu) - per_cpu_ptr(tr->array_buffer.data, cpu)->ftrace_ignore_pid = FTRACE_PID_TRACE; + if (type & TRACE_PIDS) + rcu_assign_pointer(tr->function_pids, NULL); - rcu_assign_pointer(tr->function_pids, NULL); + if (type & TRACE_NO_PIDS) + rcu_assign_pointer(tr->function_no_pids, NULL); /* Wait till all users are no longer using pid filtering */ synchronize_rcu(); - 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); } void ftrace_clear_pids(struct trace_array *tr) { mutex_lock(&ftrace_lock); - clear_ftrace_pids(tr); + clear_ftrace_pids(tr, TRACE_PIDS | TRACE_NO_PIDS); mutex_unlock(&ftrace_lock); } -static void ftrace_pid_reset(struct trace_array *tr) +static void ftrace_pid_reset(struct trace_array *tr, int type) { mutex_lock(&ftrace_lock); - clear_ftrace_pids(tr); + clear_ftrace_pids(tr, type); ftrace_update_pid_func(); ftrace_startup_all(0); @@ -7078,9 +7108,45 @@ static const struct seq_operations ftrace_pid_sops = { .show = fpid_show, }; -static int -ftrace_pid_open(struct inode *inode, struct file *file) +static void *fnpid_start(struct seq_file *m, loff_t *pos) + __acquires(RCU) +{ + struct trace_pid_list *pid_list; + struct trace_array *tr = m->private; + + mutex_lock(&ftrace_lock); + rcu_read_lock_sched(); + + pid_list = rcu_dereference_sched(tr->function_no_pids); + + if (!pid_list) + return !(*pos) ? FTRACE_NO_PIDS : NULL; + + return trace_pid_start(pid_list, pos); +} + +static void *fnpid_next(struct seq_file *m, void *v, loff_t *pos) { + struct trace_array *tr = m->private; + struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_no_pids); + + if (v == FTRACE_NO_PIDS) { + (*pos)++; + return NULL; + } + return trace_pid_next(pid_list, v, pos); +} + +static const struct seq_operations ftrace_no_pid_sops = { + .start = fnpid_start, + .next = fnpid_next, + .stop = fpid_stop, + .show = fpid_show, +}; + +static int pid_open(struct inode *inode, struct file *file, int type) +{ + const struct seq_operations *seq_ops; struct trace_array *tr = inode->i_private; struct seq_file *m; int ret = 0; @@ -7091,9 +7157,18 @@ ftrace_pid_open(struct inode *inode, struct file *file) if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) - ftrace_pid_reset(tr); + ftrace_pid_reset(tr, type); + + switch (type) { + case TRACE_PIDS: + seq_ops = &ftrace_pid_sops; + break; + case TRACE_NO_PIDS: + seq_ops = &ftrace_no_pid_sops; + break; + } - ret = seq_open(file, &ftrace_pid_sops); + ret = seq_open(file, seq_ops); if (ret < 0) { trace_array_put(tr); } else { @@ -7105,10 +7180,23 @@ ftrace_pid_open(struct inode *inode, struct file *file) return ret; } +static int +ftrace_pid_open(struct inode *inode, struct file *file) +{ + return pid_open(inode, file, TRACE_PIDS); +} + +static int +ftrace_no_pid_open(struct inode *inode, struct file *file) +{ + return pid_open(inode, file, TRACE_NO_PIDS); +} + 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 @@ -7116,8 +7204,10 @@ static void ignore_task_cpu(void *data) */ pid_list = rcu_dereference_protected(tr->function_pids, mutex_is_locked(&ftrace_lock)); + no_pid_list = rcu_dereference_protected(tr->function_no_pids, + mutex_is_locked(&ftrace_lock)); - if (trace_ignore_this_task(pid_list, current)) + if (trace_ignore_this_task(pid_list, no_pid_list, current)) this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid, FTRACE_PID_IGNORE); else @@ -7126,12 +7216,13 @@ static void ignore_task_cpu(void *data) } static ssize_t -ftrace_pid_write(struct file *filp, const char __user *ubuf, - size_t cnt, loff_t *ppos) +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 *filtered_pids; + struct trace_pid_list *other_pids; struct trace_pid_list *pid_list; ssize_t ret; @@ -7140,19 +7231,39 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf, mutex_lock(&ftrace_lock); - filtered_pids = rcu_dereference_protected(tr->function_pids, + switch (type) { + case TRACE_PIDS: + filtered_pids = rcu_dereference_protected(tr->function_pids, lockdep_is_held(&ftrace_lock)); + other_pids = rcu_dereference_protected(tr->function_no_pids, + lockdep_is_held(&ftrace_lock)); + break; + case TRACE_NO_PIDS: + filtered_pids = rcu_dereference_protected(tr->function_no_pids, + lockdep_is_held(&ftrace_lock)); + other_pids = rcu_dereference_protected(tr->function_pids, + lockdep_is_held(&ftrace_lock)); + break; + } ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt); if (ret < 0) goto out; - rcu_assign_pointer(tr->function_pids, pid_list); + switch (type) { + case TRACE_PIDS: + rcu_assign_pointer(tr->function_pids, pid_list); + break; + case TRACE_NO_PIDS: + rcu_assign_pointer(tr->function_no_pids, pid_list); + break; + } + if (filtered_pids) { synchronize_rcu(); trace_free_pid_list(filtered_pids); - } else if (pid_list) { + } else if (pid_list && !other_pids) { /* Register a probe to set whether to ignore the tracing of a task */ register_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr); } @@ -7175,6 +7286,20 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf, return ret; } +static ssize_t +ftrace_pid_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + return pid_write(filp, ubuf, cnt, ppos, TRACE_PIDS); +} + +static ssize_t +ftrace_no_pid_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + return pid_write(filp, ubuf, cnt, ppos, TRACE_NO_PIDS); +} + static int ftrace_pid_release(struct inode *inode, struct file *file) { @@ -7193,10 +7318,20 @@ static const struct file_operations ftrace_pid_fops = { .release = ftrace_pid_release, }; +static const struct file_operations ftrace_no_pid_fops = { + .open = ftrace_no_pid_open, + .write = ftrace_no_pid_write, + .read = seq_read, + .llseek = tracing_lseek, + .release = ftrace_pid_release, +}; + void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer) { trace_create_file("set_ftrace_pid", 0644, d_tracer, tr, &ftrace_pid_fops); + trace_create_file("set_ftrace_notrace_pid", 0644, d_tracer, + tr, &ftrace_no_pid_fops); } void __init ftrace_init_tracefs_toplevel(struct trace_array *tr, diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 5e634b9c1e0a..6519b7afc499 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -386,16 +386,22 @@ trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid) * Returns false if @task should be traced. */ bool -trace_ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task) +trace_ignore_this_task(struct trace_pid_list *filtered_pids, + struct trace_pid_list *filtered_no_pids, + struct task_struct *task) { /* - * Return false, because if filtered_pids does not exist, - * all pids are good to trace. + * If filterd_no_pids is not empty, and the task's pid is listed + * in filtered_no_pids, then return true. + * Otherwise, if filtered_pids is empty, that means we can + * trace all tasks. If it has content, then only trace pids + * within filtered_pids. */ - if (!filtered_pids) - return false; - return !trace_find_filtered_pid(filtered_pids, task->pid); + return (filtered_pids && + !trace_find_filtered_pid(filtered_pids, task->pid)) || + (filtered_no_pids && + trace_find_filtered_pid(filtered_no_pids, task->pid)); } /** @@ -5013,6 +5019,8 @@ static const char readme_msg[] = #ifdef CONFIG_FUNCTION_TRACER " set_ftrace_pid\t- Write pid(s) to only function trace those pids\n" "\t\t (function)\n" + " set_ftrace_notrace_pid\t- Write pid(s) to not function trace those pids\n" + "\t\t (function)\n" #endif #ifdef CONFIG_FUNCTION_GRAPH_TRACER " set_graph_function\t- Trace the nested calls of a function (function_graph)\n" diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index fdc72f5f0bb0..6b5ff5adb4ad 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -331,6 +331,7 @@ struct trace_array { #ifdef CONFIG_FUNCTION_TRACER struct ftrace_ops *ops; struct trace_pid_list __rcu *function_pids; + struct trace_pid_list __rcu *function_no_pids; #ifdef CONFIG_DYNAMIC_FTRACE /* All of these are protected by the ftrace_lock */ struct list_head func_probes; @@ -782,6 +783,7 @@ extern int pid_max; bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid); bool trace_ignore_this_task(struct trace_pid_list *filtered_pids, + struct trace_pid_list *filtered_no_pids, struct task_struct *task); void trace_filter_add_remove_task(struct trace_pid_list *pid_list, struct task_struct *self, diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index f38234ecea18..c196d0dc5871 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -549,8 +549,8 @@ event_filter_pid_sched_switch_probe_pre(void *data, bool preempt, pid_list = rcu_dereference_sched(tr->filtered_pids); this_cpu_write(tr->array_buffer.data->ignore_pid, - trace_ignore_this_task(pid_list, prev) && - trace_ignore_this_task(pid_list, next)); + trace_ignore_this_task(pid_list, NULL, prev) && + trace_ignore_this_task(pid_list, NULL, next)); } static void @@ -563,7 +563,7 @@ event_filter_pid_sched_switch_probe_post(void *data, bool preempt, pid_list = rcu_dereference_sched(tr->filtered_pids); this_cpu_write(tr->array_buffer.data->ignore_pid, - trace_ignore_this_task(pid_list, next)); + trace_ignore_this_task(pid_list, NULL, next)); } static void @@ -579,7 +579,7 @@ event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task) pid_list = rcu_dereference_sched(tr->filtered_pids); this_cpu_write(tr->array_buffer.data->ignore_pid, - trace_ignore_this_task(pid_list, task)); + trace_ignore_this_task(pid_list, NULL, task)); } static void @@ -596,7 +596,7 @@ event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task) /* Set tracing if current is enabled */ this_cpu_write(tr->array_buffer.data->ignore_pid, - trace_ignore_this_task(pid_list, current)); + trace_ignore_this_task(pid_list, NULL, current)); } static void __ftrace_clear_event_pids(struct trace_array *tr) @@ -1597,7 +1597,7 @@ static void ignore_task_cpu(void *data) mutex_is_locked(&event_mutex)); this_cpu_write(tr->array_buffer.data->ignore_pid, - trace_ignore_this_task(pid_list, current)); + trace_ignore_this_task(pid_list, NULL, current)); } static ssize_t |