[for-next][PATCH 13/30] function_graph: Have profiler use new helper ftrace_graph_get_ret_stack()
From: Steven Rostedt
Date: Wed Dec 05 2018 - 18:48:39 EST
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/ftrace.h | 3 +++
kernel/trace/fgraph.c | 11 +++++++++++
kernel/trace/ftrace.c | 21 +++++++++++----------
3 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 21c80491ccde..98e141c71ad0 100644
--- 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 90fcefcaff2a..a3704ec8b599 100644
--- 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 ¤t->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 d06fe588e650..8ef9fc226037 100644
--- 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;
}
--
2.19.1