/* * trace event based perf event profiling/tracing * * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra * Copyright (C) 2009-2010 Frederic Weisbecker */ #include #include #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_TRACER static void perf_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); memset(®s, 0, sizeof(regs)); perf_fetch_caller_regs(®s); 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, ®s, 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_PER_CPU | FTRACE_OPS_FL_RCU; 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 */