function_graph: Create function_graph_enter() to consolidate architecture code

BugLink: https://bugs.launchpad.net/bugs/1836968
commit 8114865ff82e200b383e46821c25cb0625b842b5 upstream.

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@kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 3319df9727aa23744f17d56637d9a160d628541a..cd7d2d7b56f35b21a98ebdb9f4697e764b23ca88 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -799,6 +799,9 @@ 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 169b3c44ee97f3cf00bc574b185f16fa572a12d5..28f2602435d057b15127da904d82d5d31b0635cd 100644 (file)
--- 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,