linux-kernel - [PATCH v2 1/3] s390/unwind: drop unnecessary code around calling ftrace_graph_ret

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Date:   Tue, 29 Oct 2019 15:39:02 +0100
From:   Miroslav Benes <mbenes@...e.cz>
To:     heiko.carstens@...ibm.com, gor@...ux.ibm.com,
        borntraeger@...ibm.com, jpoimboe@...hat.com,
        joe.lawrence@...hat.com
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        jikos@...nel.org, pmladek@...e.com, nstange@...e.de,
        live-patching@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH v2 1/3] s390/unwind: drop unnecessary code around calling ftrace_graph_ret_addr()

The current code around calling ftrace_graph_ret_addr() is ifdeffed and
also tests if ftrace redirection is present on stack.
ftrace_graph_ret_addr() however performs the test internally and there
is a version for !CONFIG_FUNCTION_GRAPH_TRACER as well. The unnecessary
code can thus be dropped.

Signed-off-by: Miroslav Benes <mbenes@...e.cz>
---
 arch/s390/kernel/unwind_bc.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index 8fc9daae47a2..b407b5531f11 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -80,12 +80,8 @@ bool unwind_next_frame(struct unwind_state *state)
 		}
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, (void *) sp);
-#endif
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				   ip, (void *) sp);
 
 	/* Update unwind state */
 	state->sp = sp;
@@ -140,12 +136,8 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		reliable = false;
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, NULL);
-#endif
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				   ip, NULL);
 
 	/* Update unwind state */
 	state->sp = sp;
-- 
2.23.0