From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Date: Sun, 18 Nov 2018 22:19:26 +0000 (-0500)
Subject: ARM: function_graph: Simplify with function_graph_enter()
X-Git-Tag: v4.20-rc5~25^2~16
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f1f5b14afd7cce39e6a9b25c685e1ea34c231096;p=thirdparty%2Flinux.git

ARM: 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 ARM 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: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
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/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 0142fcfcc3d37..bda949fd84e8b 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -183,9 +183,7 @@ 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;
@@ -193,21 +191,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 	old = *parent;
 	*parent = return_hooker;
 
-	trace.func = self_addr;
-	trace.depth = current->curr_ret_stack + 1;
-
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace)) {
+	if (function_graph_enter(old, self_addr, frame_pointer, NULL))
 		*parent = old;
-		return;
-	}
-
-	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
-				       frame_pointer, NULL);
-	if (err == -EBUSY) {
-		*parent = old;
-		return;
-	}
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE