/* * trace event based perf event profiling/tracing * * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com> * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com> */ #include <linux/module.h>#include <linux/kprobes.h>#include "trace.h" static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS]; /* * Force it to be aligned to unsigned long to avoid misaligned accesses * suprises */typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])	perf_trace_t; /* Count the events in use (per event id, not per instance) */static int	total_ref_count; static int perf_trace_event_perm(struct trace_event_call *tp_event,				 struct perf_event *p_event){	if (tp_event->perf_perm) {		int ret = tp_event->perf_perm(tp_event, p_event);		if (ret)			return ret;	} 	/*	 * We checked and allowed to create parent,	 * allow children without checking.	 */	if (p_event->parent)		return 0; 	/*	 * It's ok to check current process (owner) permissions in here,	 * because code below is called only via perf_event_open syscall.	 */ 	/* The ftrace function trace is allowed only for root. */	if (ftrace_event_is_function(tp_event)) {		if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))			return -EPERM; 		/*		 * We don't allow user space callchains for  function trace		 * event, due to issues with page faults while tracing page		 * fault handler and its overall trickiness nature.		 */		if (!p_event->attr.exclude_callchain_user)			return -EINVAL; 		/*		 * Same reason to disable user stack dump as for user space		 * callchains above.		 */		if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)			return -EINVAL;	} 	/* No tracing, just counting, so no obvious leak */	if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))		return 0; 	/* Some events are ok to be traced by non-root users... */	if (p_event->attach_state == PERF_ATTACH_TASK) {		if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)			return 0;	} 	/*	 * ...otherwise raw tracepoint data can be a severe data leak,	 * only allow root to have these.	 */	if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))		return -EPERM; 	return 0;} static int perf_trace_event_reg(struct trace_event_call *tp_event,				struct perf_event *p_event){	struct hlist_head __percpu *list;	int ret = -ENOMEM;	int cpu; 	p_event->tp_event = tp_event;	if (tp_event->perf_refcount++ > 0)		return 0; 	list = alloc_percpu(struct hlist_head);	if (!list)		goto fail; 	for_each_possible_cpu(cpu)		INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); 	tp_event->perf_events = list; 	if (!total_ref_count) {		char __percpu *buf;		int i; 		for (i = 0; i < PERF_NR_CONTEXTS; i++) {			buf = (char __percpu *)alloc_percpu(perf_trace_t);			if (!buf)				goto fail; 			perf_trace_buf[i] = buf;		}	} 	ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);	if (ret)		goto fail; 	total_ref_count++;	return 0; fail:	if (!total_ref_count) {		int i; 		for (i = 0; i < PERF_NR_CONTEXTS; i++) {			free_percpu(perf_trace_buf[i]);			perf_trace_buf[i] = NULL;		}	} 	if (!--tp_event->perf_refcount) {		free_percpu(tp_event->perf_events);		tp_event->perf_events = NULL;	} 	return ret;} static void perf_trace_event_unreg(struct perf_event *p_event){	struct trace_event_call *tp_event = p_event->tp_event;	int i; 	if (--tp_event->perf_refcount > 0)		goto out; 	tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); 	/*	 * Ensure our callback won't be called anymore. The buffers	 * will be freed after that.	 */	tracepoint_synchronize_unregister(); 	free_percpu(tp_event->perf_events);	tp_event->perf_events = NULL; 	if (!--total_ref_count) {		for (i = 0; i < PERF_NR_CONTEXTS; i++) {			free_percpu(perf_trace_buf[i]);			perf_trace_buf[i] = NULL;		}	}out:	module_put(tp_event->mod);} static int perf_trace_event_open(struct perf_event *p_event){	struct trace_event_call *tp_event = p_event->tp_event;	return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);} static void perf_trace_event_close(struct perf_event *p_event){	struct trace_event_call *tp_event = p_event->tp_event;	tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);} static int perf_trace_event_init(struct trace_event_call *tp_event,				 struct perf_event *p_event){	int ret; 	ret = perf_trace_event_perm(tp_event, p_event);	if (ret)		return ret; 	ret = perf_trace_event_reg(tp_event, p_event);	if (ret)		return ret; 	ret = perf_trace_event_open(p_event);	if (ret) {		perf_trace_event_unreg(p_event);		return ret;	} 	return 0;} int perf_trace_init(struct perf_event *p_event){	struct trace_event_call *tp_event;	u64 event_id = p_event->attr.config;	int ret = -EINVAL; 	mutex_lock(&event_mutex);	list_for_each_entry(tp_event, &ftrace_events, list) {		if (tp_event->event.type == event_id &&		    tp_event->class && tp_event->class->reg &&		    try_module_get(tp_event->mod)) {			ret = perf_trace_event_init(tp_event, p_event);			if (ret)				module_put(tp_event->mod);			break;		}	}	mutex_unlock(&event_mutex); 	return ret;} void perf_trace_destroy(struct perf_event *p_event){	mutex_lock(&event_mutex);	perf_trace_event_close(p_event);	perf_trace_event_unreg(p_event);	mutex_unlock(&event_mutex);} int perf_trace_add(struct perf_event *p_event, int flags){	struct trace_event_call *tp_event = p_event->tp_event;	struct hlist_head __percpu *pcpu_list;	struct hlist_head *list; 	pcpu_list = tp_event->perf_events;	if (WARN_ON_ONCE(!pcpu_list))		return -EINVAL; 	if (!(flags & PERF_EF_START))		p_event->hw.state = PERF_HES_STOPPED; 	list = this_cpu_ptr(pcpu_list);	hlist_add_head_rcu(&p_event->hlist_entry, list); 	return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);} void perf_trace_del(struct perf_event *p_event, int flags){	struct trace_event_call *tp_event = p_event->tp_event;	hlist_del_rcu(&p_event->hlist_entry);	tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);} void *perf_trace_buf_prepare(int size, unsigned short type,			     struct pt_regs **regs, int *rctxp){	struct trace_entry *entry;	unsigned long flags;	char *raw_data;	int pc; 	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); 	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,			"perf buffer not large enough"))		return NULL; 	pc = preempt_count(); 	*rctxp = perf_swevent_get_recursion_context();	if (*rctxp < 0)		return NULL; 	if (regs)		*regs = this_cpu_ptr(&__perf_regs[*rctxp]);	raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); 	/* zero the dead bytes from align to not leak stack to user */	memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); 	entry = (struct trace_entry *)raw_data;	local_save_flags(flags);	tracing_generic_entry_update(entry, flags, pc);	entry->type = type; 	return raw_data;}EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);NOKPROBE_SYMBOL(perf_trace_buf_prepare); #ifdef CONFIG_FUNCTION_TRACERstatic voidperf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,			  struct ftrace_ops *ops, struct pt_regs *pt_regs){	struct ftrace_entry *entry;	struct hlist_head *head;	struct pt_regs regs;	int rctx; 	head = this_cpu_ptr(event_function.perf_events);	if (hlist_empty(head))		return; #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \		    sizeof(u64)) - sizeof(u32)) 	BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); 	perf_fetch_caller_regs(&regs); 	entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);	if (!entry)		return; 	entry->ip = ip;	entry->parent_ip = parent_ip;	perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,			      1, &regs, head, NULL); #undef ENTRY_SIZE} static int perf_ftrace_function_register(struct perf_event *event){	struct ftrace_ops *ops = &event->ftrace_ops; 	ops->flags |= FTRACE_OPS_FL_CONTROL;	ops->func = perf_ftrace_function_call;	return register_ftrace_function(ops);} static int perf_ftrace_function_unregister(struct perf_event *event){	struct ftrace_ops *ops = &event->ftrace_ops;	int ret = unregister_ftrace_function(ops);	ftrace_free_filter(ops);	return ret;} static void perf_ftrace_function_enable(struct perf_event *event){	ftrace_function_local_enable(&event->ftrace_ops);} static void perf_ftrace_function_disable(struct perf_event *event){	ftrace_function_local_disable(&event->ftrace_ops);} int perf_ftrace_event_register(struct trace_event_call *call,			       enum trace_reg type, void *data){	switch (type) {	case TRACE_REG_REGISTER:	case TRACE_REG_UNREGISTER:		break;	case TRACE_REG_PERF_REGISTER:	case TRACE_REG_PERF_UNREGISTER:		return 0;	case TRACE_REG_PERF_OPEN:		return perf_ftrace_function_register(data);	case TRACE_REG_PERF_CLOSE:		return perf_ftrace_function_unregister(data);	case TRACE_REG_PERF_ADD:		perf_ftrace_function_enable(data);		return 0;	case TRACE_REG_PERF_DEL:		perf_ftrace_function_disable(data);		return 0;	} 	return -EINVAL;}#endif /* CONFIG_FUNCTION_TRACER */