1 files changed, 175 insertions, 0 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
new file mode 100644
index 000000000000..0565bb42566f
--- /dev/null
+++ b/kernel/trace/trace_event_perf.c
@@ -0,0 +1,175 @@
+/*
+ * 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"
+
+DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
+EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
+
+EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
+
+static char *perf_trace_buf;
+static char *perf_trace_buf_nmi;
+
+/*
+ * 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_enable(struct ftrace_event_call *event)
+{
+	char *buf;
+	int ret = -ENOMEM;
+
+	if (event->perf_refcount++ > 0)
+		return 0;
+
+	if (!total_ref_count) {
+		buf = (char *)alloc_percpu(perf_trace_t);
+		if (!buf)
+			goto fail_buf;
+
+		rcu_assign_pointer(perf_trace_buf, buf);
+
+		buf = (char *)alloc_percpu(perf_trace_t);
+		if (!buf)
+			goto fail_buf_nmi;
+
+		rcu_assign_pointer(perf_trace_buf_nmi, buf);
+	}
+
+	ret = event->perf_event_enable(event);
+	if (!ret) {
+		total_ref_count++;
+		return 0;
+	}
+
+fail_buf_nmi:
+	if (!total_ref_count) {
+		free_percpu(perf_trace_buf_nmi);
+		free_percpu(perf_trace_buf);
+		perf_trace_buf_nmi = NULL;
+		perf_trace_buf = NULL;
+	}
+fail_buf:
+	event->perf_refcount--;
+
+	return ret;
+}
+
+int perf_trace_enable(int event_id)
+{
+	struct ftrace_event_call *event;
+	int ret = -EINVAL;
+
+	mutex_lock(&event_mutex);
+	list_for_each_entry(event, &ftrace_events, list) {
+		if (event->id == event_id && event->perf_event_enable &&
+		    try_module_get(event->mod)) {
+			ret = perf_trace_event_enable(event);
+			break;
+		}
+	}
+	mutex_unlock(&event_mutex);
+
+	return ret;
+}
+
+static void perf_trace_event_disable(struct ftrace_event_call *event)
+{
+	char *buf, *nmi_buf;
+
+	if (--event->perf_refcount > 0)
+		return;
+
+	event->perf_event_disable(event);
+
+	if (!--total_ref_count) {
+		buf = perf_trace_buf;
+		rcu_assign_pointer(perf_trace_buf, NULL);
+
+		nmi_buf = perf_trace_buf_nmi;
+		rcu_assign_pointer(perf_trace_buf_nmi, NULL);
+
+		/*
+		 * Ensure every events in profiling have finished before
+		 * releasing the buffers
+		 */
+		synchronize_sched();
+
+		free_percpu(buf);
+		free_percpu(nmi_buf);
+	}
+}
+
+void perf_trace_disable(int event_id)
+{
+	struct ftrace_event_call *event;
+
+	mutex_lock(&event_mutex);
+	list_for_each_entry(event, &ftrace_events, list) {
+		if (event->id == event_id) {
+			perf_trace_event_disable(event);
+			module_put(event->mod);
+			break;
+		}
+	}
+	mutex_unlock(&event_mutex);
+}
+
+__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
+				       int *rctxp, unsigned long *irq_flags)
+{
+	struct trace_entry *entry;
+	char *trace_buf, *raw_data;
+	int pc, cpu;
+
+	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
+
+	pc = preempt_count();
+
+	/* Protect the per cpu buffer, begin the rcu read side */
+	local_irq_save(*irq_flags);
+
+	*rctxp = perf_swevent_get_recursion_context();
+	if (*rctxp < 0)
+		goto err_recursion;
+
+	cpu = smp_processor_id();
+
+	if (in_nmi())
+		trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
+	else
+		trace_buf = rcu_dereference_sched(perf_trace_buf);
+
+	if (!trace_buf)
+		goto err;
+
+	raw_data = per_cpu_ptr(trace_buf, cpu);
+
+	/* 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;
+	tracing_generic_entry_update(entry, *irq_flags, pc);
+	entry->type = type;
+
+	return raw_data;
+err:
+	perf_swevent_put_recursion_context(*rctxp);
+err_recursion:
+	local_irq_restore(*irq_flags);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);