linux-kernel - [for-next][PATCH 11/18] s390/function_graph: Simplify with function_graph

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Date:   Wed, 21 Nov 2018 19:28:12 -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>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Julian Wiedmann <jwi@...ux.ibm.com>,
        linux-s390@...r.kernel.org, stable@...nel.org
Subject: [for-next][PATCH 11/18] s390/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 s390 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: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Julian Wiedmann <jwi@...ux.ibm.com>
Cc: linux-s390@...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/s390/kernel/ftrace.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 84be7f02d0c2..39b13d71a8fe 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -203,22 +203,13 @@ device_initcall(ftrace_plt_init);
  */
 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
 {
-	struct ftrace_graph_ent trace;
-
 	if (unlikely(ftrace_graph_is_dead()))
 		goto out;
 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		goto out;
 	ip -= MCOUNT_INSN_SIZE;
-	trace.func = ip;
-	trace.depth = current->curr_ret_stack + 1;
-	/* Only trace if the calling function expects to. */
-	if (!ftrace_graph_entry(&trace))
-		goto out;
-	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
-				     NULL) == -EBUSY)
-		goto out;
-	parent = (unsigned long) return_to_handler;
+	if (!function_graph_enter(parent, ip, 0, NULL))
+		parent = (unsigned long) return_to_handler;
 out:
 	return parent;
 }
-- 
2.19.1