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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From bc715ee4dbc5db462c59b9cfba92d31b3274fe3a Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Date: Sun, 18 Nov 2018 17:35:37 -0500
Subject: [PATCH] sh/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 superh 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: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: linux-sh@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxx
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c
index 96dd9f7da250..1b04270e5460 100644
--- a/arch/sh/kernel/ftrace.c
+++ b/arch/sh/kernel/ftrace.c
@@ -321,8 +321,7 @@ int ftrace_disable_ftrace_graph_caller(void)
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;
if (unlikely(ftrace_graph_is_dead()))
@@ -365,18 +364,7 @@ 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))
__raw_writel(old, parent);
- return;
- }
-
- trace.func = self_addr;
-
- /* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace)) {
- current->curr_ret_stack--;
- __raw_writel(old, parent);
- }
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
