The patch below does not apply to the 4.4-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 556763e5a500d71879d632867b75826551acd49c Mon Sep 17 00:00:00 2001

From: "Steven Rostedt (VMware)" rostedt@goodmis.org Date: Sun, 18 Nov 2018 17:23:30 -0500 Subject: [PATCH] microblaze: 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 microblaze 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: Michal Simek monstr@monstr.eu 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/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c index d57563c58a26..224eea40e1ee 100644 --- a/arch/microblaze/kernel/ftrace.c +++ b/arch/microblaze/kernel/ftrace.c @@ -22,8 +22,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) { unsigned long old; - int faulted, err; - struct ftrace_graph_ent trace; + int faulted; unsigned long return_hooker = (unsigned long) &return_to_handler;

@@ -63,18 +62,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) return; }

- err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL); - if (err == -EBUSY) { + if (function_graph_enter(old, self_addr, 0, NULL)) *parent = old; - return; - } - - trace.func = self_addr; - /* Only trace if the calling function expects to */ - if (!ftrace_graph_entry(&trace)) { - current->curr_ret_stack--; - *parent = old; - } } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */