/* * 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 ftrace_event_call *tp_event,				 struct perf_event *p_event){	/* 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_init(struct ftrace_event_call *tp_event,				 struct perf_event *p_event){	struct hlist_head __percpu *list;	int ret;	int cpu; 	ret = perf_trace_event_perm(tp_event, p_event);	if (ret)		return ret; 	p_event->tp_event = tp_event;	if (tp_event->perf_refcount++ > 0)		return 0; 	ret = -ENOMEM; 	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);	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;} int perf_trace_init(struct perf_event *p_event){	struct ftrace_event_call *tp_event;	int 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;} int perf_trace_add(struct perf_event *p_event, int flags){	struct ftrace_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 0;} void perf_trace_del(struct perf_event *p_event, int flags){	hlist_del_rcu(&p_event->hlist_entry);} void perf_trace_destroy(struct perf_event *p_event){	struct ftrace_event_call *tp_event = p_event->tp_event;	int i; 	mutex_lock(&event_mutex);	if (--tp_event->perf_refcount > 0)		goto out; 	tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER); 	/*	 * 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);	mutex_unlock(&event_mutex);} __kprobes 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)); 	pc = preempt_count(); 	*rctxp = perf_swevent_get_recursion_context();	if (*rctxp < 0)		return NULL; 	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);