--- /dev/null
+/*
+ * 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)
+{
+ 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 ftrace_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 ftrace_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 ftrace_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 ftrace_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 ftrace_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 ftrace_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 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 tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
+}
+
+void perf_trace_del(struct perf_event *p_event, int flags)
+{
+ struct ftrace_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);
+
+ 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_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 ftrace_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 */
Code Review / kvmfornfv.git / blobdiff