ftrace: add stack trace to function tracer

[pandora-kernel.git] / kernel / trace / trace_functions.c

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 9236d7e..3a5fa08 100644 (file)
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -16,6 +16,8 @@
 
 #include "trace.h"
 
+static struct trace_array      *func_trace;
+
 static void start_function_trace(struct trace_array *tr)
 {
        tr->cpu = get_cpu();
@@ -34,6 +36,7 @@ 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;
 }
@@ -48,12 +51,93 @@ static void function_trace_start(struct trace_array *tr)
        tracing_reset_online_cpus(tr);
 }
 
+static void
+function_stack_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();
+               /*
+                * skip over 5 funcs:
+                *    __ftrace_trace_stack,
+                *    __trace_stack,
+                *    function_stack_trace_call
+                *    ftrace_list_func
+                *    ftrace_call
+                */
+               __trace_stack(tr, data, flags, 5, pc);
+       }
+
+       atomic_dec(&data->disabled);
+       local_irq_restore(flags);
+}
+
+static struct ftrace_ops trace_stack_ops __read_mostly =
+{
+       .func = function_stack_trace_call,
+};
+
+/* Our two options */
+enum {
+       TRACE_FUNC_OPT_STACK = 0x1,
+};
+
+static struct tracer_opt func_opts[] = {
+#ifdef CONFIG_STACKTRACE
+       { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
+#endif
+       { } /* Always set a last empty entry */
+};
+
+static struct tracer_flags func_flags = {
+       .val = 0, /* By default: all flags disabled */
+       .opts = func_opts
+};
+
+static int func_set_flag(u32 old_flags, u32 bit, int set)
+{
+       if (bit == TRACE_FUNC_OPT_STACK) {
+               /* do nothing if already set */
+               if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
+                       return 0;
+
+               if (set)
+                       register_ftrace_function(&trace_stack_ops);
+               else
+                       unregister_ftrace_function(&trace_stack_ops);
+
+               return 0;
+       }
+
+       return -EINVAL;
+}
+
 static struct tracer function_trace __read_mostly =
 {
        .name        = "function",
        .init        = function_trace_init,
        .reset       = function_trace_reset,
        .start       = function_trace_start,
+       .flags          = &func_flags,
+       .set_flag       = func_set_flag,
 #ifdef CONFIG_FTRACE_SELFTEST
        .selftest    = trace_selftest_startup_function,
 #endif