From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Currently all the architectures do basically the same thing in preparing the
function graph tracer on entry to a function. This code can be pulled into a
generic location and then this will allow the function graph tracer to be
fixed, as well as extended.
Create a new function graph helper function_graph_enter() that will call the
hook function (ftrace_graph_entry) and the shadow stack operation
(ftrace_push_return_trace), and remove the need of the architecture code to
manage the shadow stack.
This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.
Cc: stable@xxxxxxxxxx
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/ftrace.h | 3 +++
kernel/trace/trace_functions_graph.c | 16 ++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index a397907e8d72..5717e8f81c59 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -779,6 +779,9 @@ extern void return_to_handler(void);
extern int
ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
unsigned long frame_pointer, unsigned long *retp);
+extern int
+function_graph_enter(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp);
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 169b3c44ee97..28f2602435d0 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -182,6 +182,22 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
return 0;
}
+int function_graph_enter(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp)
+{
+ struct ftrace_graph_ent trace;
+
+ trace.func = func;
+ trace.depth = current->curr_ret_stack + 1;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace))
+ return -EBUSY;
+
+ return ftrace_push_return_trace(ret, func, &trace.depth,
+ frame_pointer, retp);
+}
+
/* Retrieve a function return address to the trace stack on thread info.*/
static void
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
--
2.19.1
