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tracing: Update modules to persistent instances when loaded

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When a module is loaded and a persistent buffer is actively tracing, add
it to the list of modules in the persistent memory.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250305164609.469844721@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2025-03-05 11:45:47 -05:00
committed by Steven Rostedt (Google)
parent 1bd25a6f71
commit 5f3719f697
3 changed files with 57 additions and 12 deletions
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27
kernel/trace/trace.c
View File

@@ -10087,6 +10087,32 @@ static void trace_module_remove_evals(struct module *mod)
static inline void trace_module_remove_evals(struct module *mod) { }
#endif /* CONFIG_TRACE_EVAL_MAP_FILE */
static bool trace_array_active(struct trace_array *tr)
{
if (tr->current_trace != &nop_trace)
return true;
/* 0 is no events, 1 is all disabled */
return trace_events_enabled(tr, NULL) > 1;
}
static void trace_module_record(struct module *mod)
{
struct trace_array *tr;
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
/* Update any persistent trace array that has already been started */
if ((tr->flags & (TRACE_ARRAY_FL_BOOT | TRACE_ARRAY_FL_LAST_BOOT)) ==
TRACE_ARRAY_FL_BOOT) {
/* Only update if the trace array is active */
if (trace_array_active(tr)) {
guard(mutex)(&scratch_mutex);
save_mod(mod, tr);
}
}
}
}
static int trace_module_notify(struct notifier_block *self,
unsigned long val, void *data)
{
@@ -10095,6 +10121,7 @@ static int trace_module_notify(struct notifier_block *self,
switch (val) {
case MODULE_STATE_COMING:
trace_module_add_evals(mod);
trace_module_record(mod);
break;
case MODULE_STATE_GOING:
trace_module_remove_evals(mod);

2
kernel/trace/trace.h
View File

@@ -786,6 +786,8 @@ extern void trace_find_cmdline(int pid, char comm[]);
extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);
extern int trace_events_enabled(struct trace_array *tr, const char *system);
#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_update_tot_cnt;
extern unsigned long ftrace_number_of_pages;

40
kernel/trace/trace_events.c
View File

@@ -1818,28 +1818,28 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
return cnt;
}
static ssize_t
system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
/*
* Returns:
* 0 : no events exist?
* 1 : all events are disabled
* 2 : all events are enabled
* 3 : some events are enabled and some are enabled
*/
int trace_events_enabled(struct trace_array *tr, const char *system)
{
const char set_to_char[4] = { '?', '0', '1', 'X' };
struct trace_subsystem_dir *dir = filp->private_data;
struct event_subsystem *system = dir->subsystem;
struct trace_event_call *call;
struct trace_event_file *file;
struct trace_array *tr = dir->tr;
char buf[2];
int set = 0;
int ret;
mutex_lock(&event_mutex);
guard(mutex)(&event_mutex);
list_for_each_entry(file, &tr->events, list) {
call = file->event_call;
if ((call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||
!trace_event_name(call) || !call->class || !call->class->reg)
continue;
if (system && strcmp(call->class->system, system->name) != 0)
if (system && strcmp(call->class->system, system) != 0)
continue;
/*
@@ -1855,7 +1855,23 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
if (set == 3)
break;
}
mutex_unlock(&event_mutex);
return set;
}
static ssize_t
system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
const char set_to_char[4] = { '?', '0', '1', 'X' };
struct trace_subsystem_dir *dir = filp->private_data;
struct event_subsystem *system = dir->subsystem;
struct trace_array *tr = dir->tr;
char buf[2];
int set;
int ret;
set = trace_events_enabled(tr, system ? system->name : NULL);
buf[0] = set_to_char[set];
buf[1] = '\n';