1 files changed, 83 insertions, 1 deletions

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 3a5fa08cedb..2dce3c7370d 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -20,6 +20,7 @@ static struct trace_array	*func_trace;
 
 static void start_function_trace(struct trace_array *tr)
 {
+        func_trace = tr;
         tr->cpu = get_cpu();
         tracing_reset_online_cpus(tr);
         put_cpu();
@@ -36,7 +37,6 @@ static void stop_function_trace(struct trace_array *tr)
 
 static int function_trace_init(struct trace_array *tr)
 {
-        func_trace = tr;
         start_function_trace(tr);
         return 0;
 }
@@ -52,6 +52,64 @@ static void function_trace_start(struct trace_array *tr)
 }
 
 static void
+function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
+{
+        struct trace_array *tr = func_trace;
+        struct trace_array_cpu *data;
+        unsigned long flags;
+        long disabled;
+        int cpu, resched;
+        int pc;
+
+        if (unlikely(!ftrace_function_enabled))
+                return;
+
+        pc = preempt_count();
+        resched = ftrace_preempt_disable();
+        local_save_flags(flags);
+        cpu = raw_smp_processor_id();
+        data = tr->data[cpu];
+        disabled = atomic_inc_return(&data->disabled);
+
+        if (likely(disabled == 1))
+                trace_function(tr, data, ip, parent_ip, flags, pc);
+
+        atomic_dec(&data->disabled);
+        ftrace_preempt_enable(resched);
+}
+
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip)
+{
+        struct trace_array *tr = func_trace;
+        struct trace_array_cpu *data;
+        unsigned long flags;
+        long disabled;
+        int cpu;
+        int pc;
+
+        if (unlikely(!ftrace_function_enabled))
+                return;
+
+        /*
+         * Need to use raw, since this must be called before the
+         * recursive protection is performed.
+         */
+        local_irq_save(flags);
+        cpu = raw_smp_processor_id();
+        data = tr->data[cpu];
+        disabled = atomic_inc_return(&data->disabled);
+
+        if (likely(disabled == 1)) {
+                pc = preempt_count();
+                trace_function(tr, data, ip, parent_ip, flags, pc);
+        }
+
+        atomic_dec(&data->disabled);
+        local_irq_restore(flags);
+}
+
+static void
 function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
 {
         struct trace_array *tr = func_trace;
@@ -90,6 +148,30 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
         local_irq_restore(flags);
 }
 
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+        .func = function_trace_call,
+};
+
+void tracing_start_function_trace(void)
+{
+        ftrace_function_enabled = 0;
+
+        if (trace_flags & TRACE_ITER_PREEMPTONLY)
+                trace_ops.func = function_trace_call_preempt_only;
+        else
+                trace_ops.func = function_trace_call;
+
+        register_ftrace_function(&trace_ops);
+        ftrace_function_enabled = 1;
+}
+
+void tracing_stop_function_trace(void)
+{
+        ftrace_function_enabled = 0;
+        unregister_ftrace_function(&trace_ops);
+}
 static struct ftrace_ops trace_stack_ops __read_mostly =
 {
         .func = function_stack_trace_call,