linux-kernel - [for-next][PATCH 08/18] parisc: function_graph: Simplify with function_graph

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Message-Id: <20181122003332.500796758@goodmis.org>
Date:   Wed, 21 Nov 2018 19:28:09 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-arch@...r.kernel.org,
        Joel Fernandes <joel@...lfernandes.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        "James E.J. Bottomley" <jejb@...isc-linux.org>,
        Helge Deller <deller@....de>, linux-parisc@...r.kernel.org,
        stable@...nel.org
Subject: [for-next][PATCH 08/18] parisc: function_graph: Simplify with function_graph_entry()

From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>

The function_graph_entry() 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 parisc 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: "James E.J. Bottomley" <jejb@...isc-linux.org>
Cc: Helge Deller <deller@....de>
Cc: linux-parisc@...r.kernel.org
Cc: stable@...nel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 arch/parisc/kernel/ftrace.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 6fa8535d3cce..e46a4157a894 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -30,7 +30,6 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
 					unsigned long self_addr)
 {
 	unsigned long old;
-	struct ftrace_graph_ent trace;
 	extern int parisc_return_to_handler;
 
 	if (unlikely(ftrace_graph_is_dead()))
@@ -41,19 +40,9 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
 
 	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;
-
-        if (ftrace_push_return_trace(old, self_addr, &trace.depth,
-				     0, NULL) == -EBUSY)
-                return;
-
-	/* activate parisc_return_to_handler() as return point */
-	*parent = (unsigned long) &parisc_return_to_handler;
+	if (!function_graph_enter(old, self_addr, 0, NULL))
+		/* activate parisc_return_to_handler() as return point */
+		*parent = (unsigned long) &parisc_return_to_handler;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
-- 
2.19.1