The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d48ebb24866edea2c35be02a878f25bc65529370 Mon Sep 17 00:00:00 2001

From: "Steven Rostedt (VMware)" rostedt@goodmis.org Date: Sun, 18 Nov 2018 17:26:35 -0500 Subject: [PATCH] nds32: function_graph: Simplify with function_graph_enter()

The function_graph_enter() function does the work of calling the function graph hook function and the management of the shadow stack, simplifying the work done in the architecture dependent prepare_ftrace_return().

Have nds32 use the new code, and remove the shadow stack management as well as having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack is used.

Cc: Greentime Hu greentime@andestech.com 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

diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c index a0a9679ad5de..8a41372551ff 100644 --- a/arch/nds32/kernel/ftrace.c +++ b/arch/nds32/kernel/ftrace.c @@ -211,29 +211,15 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, unsigned long frame_pointer) { unsigned long return_hooker = (unsigned long)&return_to_handler; - struct ftrace_graph_ent trace; unsigned long old; - int err;

if (unlikely(atomic_read(&current->tracing_graph_pause))) return;

old = *parent;

- trace.func = self_addr; - trace.depth = current->curr_ret_stack + 1; - - /* Only trace if the calling function expects to */ - if (!ftrace_graph_entry(&trace)) - return; - - err = ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer, NULL); - - if (err == -EBUSY) - return; - - *parent = return_hooker; + if (!function_graph_enter(old, self_addr, frame_pointer, NULL)) + *parent = return_hooker; }

noinline void ftrace_graph_caller(void)