diff options
Diffstat (limited to 'kernel/trace/ftrace.c')
-rw-r--r-- | kernel/trace/ftrace.c | 281 |
1 files changed, 190 insertions, 91 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 22fa5569676..cd7f76d1eb8 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -85,6 +85,8 @@ int function_trace_stop __read_mostly; /* Current function tracing op */ struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end; +/* What to set function_trace_op to */ +static struct ftrace_ops *set_function_trace_op; /* List for set_ftrace_pid's pids. */ LIST_HEAD(ftrace_pids); @@ -278,6 +280,29 @@ static void update_global_ops(void) global_ops.func = func; } +static void ftrace_sync(struct work_struct *work) +{ + /* + * This function is just a stub to implement a hard force + * of synchronize_sched(). This requires synchronizing + * tasks even in userspace and idle. + * + * Yes, function tracing is rude. + */ +} + +static void ftrace_sync_ipi(void *data) +{ + /* Probably not needed, but do it anyway */ + smp_rmb(); +} + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +static void update_function_graph_func(void); +#else +static inline void update_function_graph_func(void) { } +#endif + static void update_ftrace_function(void) { ftrace_func_t func; @@ -296,16 +321,61 @@ static void update_ftrace_function(void) !FTRACE_FORCE_LIST_FUNC)) { /* Set the ftrace_ops that the arch callback uses */ if (ftrace_ops_list == &global_ops) - function_trace_op = ftrace_global_list; + set_function_trace_op = ftrace_global_list; else - function_trace_op = ftrace_ops_list; + set_function_trace_op = ftrace_ops_list; func = ftrace_ops_list->func; } else { /* Just use the default ftrace_ops */ - function_trace_op = &ftrace_list_end; + set_function_trace_op = &ftrace_list_end; func = ftrace_ops_list_func; } + /* If there's no change, then do nothing more here */ + if (ftrace_trace_function == func) + return; + + update_function_graph_func(); + + /* + * If we are using the list function, it doesn't care + * about the function_trace_ops. + */ + if (func == ftrace_ops_list_func) { + ftrace_trace_function = func; + /* + * Don't even bother setting function_trace_ops, + * it would be racy to do so anyway. + */ + return; + } + +#ifndef CONFIG_DYNAMIC_FTRACE + /* + * For static tracing, we need to be a bit more careful. + * The function change takes affect immediately. Thus, + * we need to coorditate the setting of the function_trace_ops + * with the setting of the ftrace_trace_function. + * + * Set the function to the list ops, which will call the + * function we want, albeit indirectly, but it handles the + * ftrace_ops and doesn't depend on function_trace_op. + */ + ftrace_trace_function = ftrace_ops_list_func; + /* + * Make sure all CPUs see this. Yes this is slow, but static + * tracing is slow and nasty to have enabled. + */ + schedule_on_each_cpu(ftrace_sync); + /* Now all cpus are using the list ops. */ + function_trace_op = set_function_trace_op; + /* Make sure the function_trace_op is visible on all CPUs */ + smp_wmb(); + /* Nasty way to force a rmb on all cpus */ + smp_call_function(ftrace_sync_ipi, NULL, 1); + /* OK, we are all set to update the ftrace_trace_function now! */ +#endif /* !CONFIG_DYNAMIC_FTRACE */ + ftrace_trace_function = func; } @@ -367,9 +437,6 @@ static int remove_ftrace_list_ops(struct ftrace_ops **list, static int __register_ftrace_function(struct ftrace_ops *ops) { - if (unlikely(ftrace_disabled)) - return -ENODEV; - if (FTRACE_WARN_ON(ops == &global_ops)) return -EINVAL; @@ -413,24 +480,10 @@ static int __register_ftrace_function(struct ftrace_ops *ops) return 0; } -static void ftrace_sync(struct work_struct *work) -{ - /* - * This function is just a stub to implement a hard force - * of synchronize_sched(). This requires synchronizing - * tasks even in userspace and idle. - * - * Yes, function tracing is rude. - */ -} - static int __unregister_ftrace_function(struct ftrace_ops *ops) { int ret; - if (ftrace_disabled) - return -ENODEV; - if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED))) return -EBUSY; @@ -445,20 +498,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) } else if (ops->flags & FTRACE_OPS_FL_CONTROL) { ret = remove_ftrace_list_ops(&ftrace_control_list, &control_ops, ops); - if (!ret) { - /* - * The ftrace_ops is now removed from the list, - * so there'll be no new users. We must ensure - * all current users are done before we free - * the control data. - * Note synchronize_sched() is not enough, as we - * use preempt_disable() to do RCU, but the function - * tracer can be called where RCU is not active - * (before user_exit()). - */ - schedule_on_each_cpu(ftrace_sync); - control_ops_free(ops); - } } else ret = remove_ftrace_ops(&ftrace_ops_list, ops); @@ -468,17 +507,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) if (ftrace_enabled) update_ftrace_function(); - /* - * Dynamic ops may be freed, we must make sure that all - * callers are done before leaving this function. - * - * Again, normal synchronize_sched() is not good enough. - * We need to do a hard force of sched synchronization. - */ - if (ops->flags & FTRACE_OPS_FL_DYNAMIC) - schedule_on_each_cpu(ftrace_sync); - - return 0; } @@ -781,7 +809,7 @@ static int ftrace_profile_init(void) int cpu; int ret = 0; - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { ret = ftrace_profile_init_cpu(cpu); if (ret) break; @@ -1088,19 +1116,6 @@ static __init void ftrace_profile_debugfs(struct dentry *d_tracer) static struct pid * const ftrace_swapper_pid = &init_struct_pid; -loff_t -ftrace_filter_lseek(struct file *file, loff_t offset, int whence) -{ - loff_t ret; - - if (file->f_mode & FMODE_READ) - ret = seq_lseek(file, offset, whence); - else - file->f_pos = ret = 1; - - return ret; -} - #ifdef CONFIG_DYNAMIC_FTRACE #ifndef CONFIG_FTRACE_MCOUNT_RECORD @@ -1998,8 +2013,14 @@ void ftrace_modify_all_code(int command) else if (command & FTRACE_DISABLE_CALLS) ftrace_replace_code(0); - if (update && ftrace_trace_function != ftrace_ops_list_func) + if (update && ftrace_trace_function != ftrace_ops_list_func) { + function_trace_op = set_function_trace_op; + smp_wmb(); + /* If irqs are disabled, we are in stop machine */ + if (!irqs_disabled()) + smp_call_function(ftrace_sync_ipi, NULL, 1); ftrace_update_ftrace_func(ftrace_trace_function); + } if (command & FTRACE_START_FUNC_RET) ftrace_enable_ftrace_graph_caller(); @@ -2088,10 +2109,15 @@ static void ftrace_startup_enable(int command) static int ftrace_startup(struct ftrace_ops *ops, int command) { bool hash_enable = true; + int ret; if (unlikely(ftrace_disabled)) return -ENODEV; + ret = __register_ftrace_function(ops); + if (ret) + return ret; + ftrace_start_up++; command |= FTRACE_UPDATE_CALLS; @@ -2113,12 +2139,17 @@ static int ftrace_startup(struct ftrace_ops *ops, int command) return 0; } -static void ftrace_shutdown(struct ftrace_ops *ops, int command) +static int ftrace_shutdown(struct ftrace_ops *ops, int command) { bool hash_disable = true; + int ret; if (unlikely(ftrace_disabled)) - return; + return -ENODEV; + + ret = __unregister_ftrace_function(ops); + if (ret) + return ret; ftrace_start_up--; /* @@ -2152,10 +2183,42 @@ static void ftrace_shutdown(struct ftrace_ops *ops, int command) command |= FTRACE_UPDATE_TRACE_FUNC; } - if (!command || !ftrace_enabled) - return; + if (!command || !ftrace_enabled) { + /* + * If these are control ops, they still need their + * per_cpu field freed. Since, function tracing is + * not currently active, we can just free them + * without synchronizing all CPUs. + */ + if (ops->flags & FTRACE_OPS_FL_CONTROL) + control_ops_free(ops); + return 0; + } ftrace_run_update_code(command); + + /* + * Dynamic ops may be freed, we must make sure that all + * callers are done before leaving this function. + * The same goes for freeing the per_cpu data of the control + * ops. + * + * Again, normal synchronize_sched() is not good enough. + * We need to do a hard force of sched synchronization. + * This is because we use preempt_disable() to do RCU, but + * the function tracers can be called where RCU is not watching + * (like before user_exit()). We can not rely on the RCU + * infrastructure to do the synchronization, thus we must do it + * ourselves. + */ + if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_CONTROL)) { + schedule_on_each_cpu(ftrace_sync); + + if (ops->flags & FTRACE_OPS_FL_CONTROL) + control_ops_free(ops); + } + + return 0; } static void ftrace_startup_sysctl(void) @@ -2734,7 +2797,7 @@ static void ftrace_filter_reset(struct ftrace_hash *hash) * routine, you can use ftrace_filter_write() for the write * routine if @flag has FTRACE_ITER_FILTER set, or * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set. - * ftrace_filter_lseek() should be used as the lseek routine, and + * tracing_lseek() should be used as the lseek routine, and * release must call ftrace_regex_release(). */ int @@ -3060,16 +3123,13 @@ static void __enable_ftrace_function_probe(void) if (i == FTRACE_FUNC_HASHSIZE) return; - ret = __register_ftrace_function(&trace_probe_ops); - if (!ret) - ret = ftrace_startup(&trace_probe_ops, 0); + ret = ftrace_startup(&trace_probe_ops, 0); ftrace_probe_registered = 1; } static void __disable_ftrace_function_probe(void) { - int ret; int i; if (!ftrace_probe_registered) @@ -3082,9 +3142,7 @@ static void __disable_ftrace_function_probe(void) } /* no more funcs left */ - ret = __unregister_ftrace_function(&trace_probe_ops); - if (!ret) - ftrace_shutdown(&trace_probe_ops, 0); + ftrace_shutdown(&trace_probe_ops, 0); ftrace_probe_registered = 0; } @@ -3767,7 +3825,7 @@ static const struct file_operations ftrace_filter_fops = { .open = ftrace_filter_open, .read = seq_read, .write = ftrace_filter_write, - .llseek = ftrace_filter_lseek, + .llseek = tracing_lseek, .release = ftrace_regex_release, }; @@ -3775,7 +3833,7 @@ static const struct file_operations ftrace_notrace_fops = { .open = ftrace_notrace_open, .read = seq_read, .write = ftrace_notrace_write, - .llseek = ftrace_filter_lseek, + .llseek = tracing_lseek, .release = ftrace_regex_release, }; @@ -4038,7 +4096,7 @@ static const struct file_operations ftrace_graph_fops = { .open = ftrace_graph_open, .read = seq_read, .write = ftrace_graph_write, - .llseek = ftrace_filter_lseek, + .llseek = tracing_lseek, .release = ftrace_graph_release, }; @@ -4046,7 +4104,7 @@ static const struct file_operations ftrace_graph_notrace_fops = { .open = ftrace_graph_notrace_open, .read = seq_read, .write = ftrace_graph_write, - .llseek = ftrace_filter_lseek, + .llseek = tracing_lseek, .release = ftrace_graph_release, }; #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ @@ -4366,12 +4424,15 @@ core_initcall(ftrace_nodyn_init); static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; } static inline void ftrace_startup_enable(int command) { } /* Keep as macros so we do not need to define the commands */ -# define ftrace_startup(ops, command) \ - ({ \ - (ops)->flags |= FTRACE_OPS_FL_ENABLED; \ - 0; \ +# define ftrace_startup(ops, command) \ + ({ \ + int ___ret = __register_ftrace_function(ops); \ + if (!___ret) \ + (ops)->flags |= FTRACE_OPS_FL_ENABLED; \ + ___ret; \ }) -# define ftrace_shutdown(ops, command) do { } while (0) +# define ftrace_shutdown(ops, command) __unregister_ftrace_function(ops) + # define ftrace_startup_sysctl() do { } while (0) # define ftrace_shutdown_sysctl() do { } while (0) @@ -4716,7 +4777,7 @@ static const struct file_operations ftrace_pid_fops = { .open = ftrace_pid_open, .write = ftrace_pid_write, .read = seq_read, - .llseek = ftrace_filter_lseek, + .llseek = tracing_lseek, .release = ftrace_pid_release, }; @@ -4780,9 +4841,7 @@ int register_ftrace_function(struct ftrace_ops *ops) mutex_lock(&ftrace_lock); - ret = __register_ftrace_function(ops); - if (!ret) - ret = ftrace_startup(ops, 0); + ret = ftrace_startup(ops, 0); mutex_unlock(&ftrace_lock); @@ -4801,9 +4860,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops) int ret; mutex_lock(&ftrace_lock); - ret = __unregister_ftrace_function(ops); - if (!ret) - ftrace_shutdown(ops, 0); + ret = ftrace_shutdown(ops, 0); mutex_unlock(&ftrace_lock); return ret; @@ -4863,6 +4920,7 @@ int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace) trace_func_graph_ret_t ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub; +static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub; /* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) @@ -4997,6 +5055,37 @@ ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state, return NOTIFY_DONE; } +/* Just a place holder for function graph */ +static struct ftrace_ops fgraph_ops __read_mostly = { + .func = ftrace_stub, + .flags = FTRACE_OPS_FL_STUB | FTRACE_OPS_FL_GLOBAL | + FTRACE_OPS_FL_RECURSION_SAFE, +}; + +static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace) +{ + if (!ftrace_ops_test(&global_ops, trace->func, NULL)) + return 0; + return __ftrace_graph_entry(trace); +} + +/* + * The function graph tracer should only trace the functions defined + * by set_ftrace_filter and set_ftrace_notrace. If another function + * tracer ops is registered, the graph tracer requires testing the + * function against the global ops, and not just trace any function + * that any ftrace_ops registered. + */ +static void update_function_graph_func(void) +{ + if (ftrace_ops_list == &ftrace_list_end || + (ftrace_ops_list == &global_ops && + global_ops.next == &ftrace_list_end)) + ftrace_graph_entry = __ftrace_graph_entry; + else + ftrace_graph_entry = ftrace_graph_entry_test; +} + int register_ftrace_graph(trace_func_graph_ret_t retfunc, trace_func_graph_ent_t entryfunc) { @@ -5021,9 +5110,18 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc, } ftrace_graph_return = retfunc; - ftrace_graph_entry = entryfunc; - ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET); + /* + * Update the indirect function to the entryfunc, and the + * function that gets called to the entry_test first. Then + * call the update fgraph entry function to determine if + * the entryfunc should be called directly or not. + */ + __ftrace_graph_entry = entryfunc; + ftrace_graph_entry = ftrace_graph_entry_test; + update_function_graph_func(); + + ret = ftrace_startup(&fgraph_ops, FTRACE_START_FUNC_RET); out: mutex_unlock(&ftrace_lock); @@ -5040,7 +5138,8 @@ void unregister_ftrace_graph(void) ftrace_graph_active--; ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; ftrace_graph_entry = ftrace_graph_entry_stub; - ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET); + __ftrace_graph_entry = ftrace_graph_entry_stub; + ftrace_shutdown(&fgraph_ops, FTRACE_STOP_FUNC_RET); unregister_pm_notifier(&ftrace_suspend_notifier); unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL); |