forked from Minki/linux
ftrace: only have ftrace_kill atomic
When an anomaly is detected, we need a way to completely disable ftrace. Right now we have two functions: ftrace_kill and ftrace_kill_atomic. The ftrace_kill tries to do it in a "nice" way by converting everything back to a nop. The "nice" way is dangerous itself, so this patch removes it and only has the "atomic" version, which is all that is needed. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -40,7 +40,7 @@ extern void ftrace_stub(unsigned long a0, unsigned long a1);
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# define register_ftrace_function(ops) do { } while (0)
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# define unregister_ftrace_function(ops) do { } while (0)
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# define clear_ftrace_function(ops) do { } while (0)
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static inline void ftrace_kill_atomic(void) { }
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static inline void ftrace_kill(void) { }
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_DYNAMIC_FTRACE
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@ -117,7 +117,6 @@ static inline void ftrace_release(void *start, unsigned long size) { }
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/* totally disable ftrace - can not re-enable after this */
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void ftrace_kill(void);
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void ftrace_kill_atomic(void);
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static inline void tracer_disable(void)
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{
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@ -1549,22 +1549,6 @@ int ftrace_force_update(void)
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return ret;
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}
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static void ftrace_force_shutdown(void)
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{
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struct task_struct *task;
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int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;
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mutex_lock(&ftraced_lock);
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task = ftraced_task;
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ftraced_task = NULL;
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ftraced_suspend = -1;
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ftrace_run_update_code(command);
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mutex_unlock(&ftraced_lock);
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if (task)
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kthread_stop(task);
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}
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static __init int ftrace_init_debugfs(void)
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{
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struct dentry *d_tracer;
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@ -1795,17 +1779,16 @@ core_initcall(ftrace_dynamic_init);
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# define ftrace_shutdown() do { } while (0)
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# define ftrace_startup_sysctl() do { } while (0)
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# define ftrace_shutdown_sysctl() do { } while (0)
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# define ftrace_force_shutdown() do { } while (0)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/**
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* ftrace_kill_atomic - kill ftrace from critical sections
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* ftrace_kill - kill ftrace
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*
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* This function should be used by panic code. It stops ftrace
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* but in a not so nice way. If you need to simply kill ftrace
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* from a non-atomic section, use ftrace_kill.
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*/
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void ftrace_kill_atomic(void)
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void ftrace_kill(void)
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{
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ftrace_disabled = 1;
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ftrace_enabled = 0;
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@ -1815,27 +1798,6 @@ void ftrace_kill_atomic(void)
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clear_ftrace_function();
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}
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/**
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* ftrace_kill - totally shutdown ftrace
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*
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* This is a safety measure. If something was detected that seems
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* wrong, calling this function will keep ftrace from doing
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* any more modifications, and updates.
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* used when something went wrong.
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*/
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void ftrace_kill(void)
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{
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mutex_lock(&ftrace_sysctl_lock);
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ftrace_disabled = 1;
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ftrace_enabled = 0;
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clear_ftrace_function();
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mutex_unlock(&ftrace_sysctl_lock);
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/* Try to totally disable ftrace */
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ftrace_force_shutdown();
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}
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/**
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* register_ftrace_function - register a function for profiling
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* @ops - ops structure that holds the function for profiling.
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@ -3097,7 +3097,7 @@ void ftrace_dump(void)
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dump_ran = 1;
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/* No turning back! */
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ftrace_kill_atomic();
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ftrace_kill();
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for_each_tracing_cpu(cpu) {
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atomic_inc(&global_trace.data[cpu]->disabled);
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