diff options
Diffstat (limited to 'kernel/trace/ftrace.c')
| -rw-r--r-- | kernel/trace/ftrace.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 422e1f8300b1..eab3123a1fbe 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2324,6 +2324,10 @@ static void ftrace_run_modify_code(struct ftrace_ops *ops, int command, static ftrace_func_t saved_ftrace_func; static int ftrace_start_up; +void __weak arch_ftrace_trampoline_free(struct ftrace_ops *ops) +{ +} + static void control_ops_free(struct ftrace_ops *ops) { free_percpu(ops->disabled); @@ -2475,6 +2479,8 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command) if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_CONTROL)) { schedule_on_each_cpu(ftrace_sync); + arch_ftrace_trampoline_free(ops); + if (ops->flags & FTRACE_OPS_FL_CONTROL) control_ops_free(ops); } @@ -4725,9 +4731,21 @@ void __weak arch_ftrace_update_trampoline(struct ftrace_ops *ops) static void ftrace_update_trampoline(struct ftrace_ops *ops) { + +/* + * Currently there's no safe way to free a trampoline when the kernel + * is configured with PREEMPT. That is because a task could be preempted + * when it jumped to the trampoline, it may be preempted for a long time + * depending on the system load, and currently there's no way to know + * when it will be off the trampoline. If the trampoline is freed + * too early, when the task runs again, it will be executing on freed + * memory and crash. + */ +#ifdef CONFIG_PREEMPT /* Currently, only non dynamic ops can have a trampoline */ if (ops->flags & FTRACE_OPS_FL_DYNAMIC) return; +#endif arch_ftrace_update_trampoline(ops); } |