function_graph: Have profiler use new helper ftrace_graph_get_ret_stack()

The ret_stack processing is going to change, and that is going
to break anything that is accessing the ret_stack directly. One user is the
function graph profiler. By using the ftrace_graph_get_ret_stack() helper
function, the profiler can access the ret_stack entry without relying on the
implementation details of the stack itself.

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 21c80491ccde4e846cab7f1206e2706cede1bceb..98e141c71ad043fb811e398a308fc4c0af5967d8 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -785,6 +785,9 @@ extern int
 function_graph_enter(unsigned long ret, unsigned long func,
                     unsigned long frame_pointer, unsigned long *retp);
 
+struct ftrace_ret_stack *
+ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
+
 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
                                    unsigned long ret, unsigned long *retp);
 

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 90fcefcaff2a314e718b9f714a296ee8e258e3ce..a3704ec8b59905276b2933bb7d2337c3f51e00af 100644 (file)
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -232,6 +232,17 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
        return ret;
 }
 
+struct ftrace_ret_stack *
+ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
+{
+       idx = current->curr_ret_stack - idx;
+
+       if (idx >= 0 && idx <= task->curr_ret_stack)
+               return &current->ret_stack[idx];
+
+       return NULL;
+}
+
 /**
  * ftrace_graph_ret_addr - convert a potentially modified stack return address
  *                        to its original value

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d06fe588e650f82250cb26e1e2385f3f2f61b764..8ef9fc22603737337463669b522649b19cc36f95 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -792,7 +792,7 @@ void ftrace_graph_graph_time_control(bool enable)
 
 static int profile_graph_entry(struct ftrace_graph_ent *trace)
 {
-       int index = current->curr_ret_stack;
+       struct ftrace_ret_stack *ret_stack;
 
        function_profile_call(trace->func, 0, NULL, NULL);
 
@@ -800,14 +800,16 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace)
        if (!current->ret_stack)
                return 0;
 
-       if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
-               current->ret_stack[index].subtime = 0;
+       ret_stack = ftrace_graph_get_ret_stack(current, 0);
+       if (ret_stack)
+               ret_stack->subtime = 0;
 
        return 1;
 }
 
 static void profile_graph_return(struct ftrace_graph_ret *trace)
 {
+       struct ftrace_ret_stack *ret_stack;
        struct ftrace_profile_stat *stat;
        unsigned long long calltime;
        struct ftrace_profile *rec;
@@ -825,16 +827,15 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
        calltime = trace->rettime - trace->calltime;
 
        if (!fgraph_graph_time) {
-               int index;
-
-               index = current->curr_ret_stack;
 
                /* Append this call time to the parent time to subtract */
-               if (index)
-                       current->ret_stack[index - 1].subtime += calltime;
+               ret_stack = ftrace_graph_get_ret_stack(current, 1);
+               if (ret_stack)
+                       ret_stack->subtime += calltime;
 
-               if (current->ret_stack[index].subtime < calltime)
-                       calltime -= current->ret_stack[index].subtime;
+               ret_stack = ftrace_graph_get_ret_stack(current, 0);
+               if (ret_stack && ret_stack->subtime < calltime)
+                       calltime -= ret_stack->subtime;
                else
                        calltime = 0;
        }