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Commit b0e21a61 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
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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: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 76b42b63

include/linux/ftrace.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

kernel/trace/fgraph.c

+11 −0
Original line number Diff line number Diff line
@@ -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

kernel/trace/ftrace.c

+11 −10
Original line number Diff line number Diff line
@@ -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;

	}