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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: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2018-11-19 20:54:08 -05:00
parent 76b42b63ed
commit b0e21a61d3
3 changed files with 25 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/ftrace.h
View File

@ -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);

11
kernel/trace/fgraph.c
View File

@ -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

21
kernel/trace/ftrace.c
View File

@ -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;
}