linux-kernel - [PATCH 1/3] ftrace: Make test_rec_ops_needs

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Message-Id: <20191007081714.20259-2-mbenes@suse.cz>
Date:   Mon,  7 Oct 2019 10:17:12 +0200
From:   Miroslav Benes <mbenes@...e.cz>
To:     rostedt@...dmis.org, mingo@...hat.com, jpoimboe@...hat.com,
        jikos@...nel.org, pmladek@...e.com, joe.lawrence@...hat.com
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 1/3] ftrace: Make test_rec_ops_needs_regs() generic

Function test_rec_ops_needs_regs() tests whether ftrace_ops registered
on a record needs saved regs. That is, it tests for
FTRACE_OPS_FL_SAVE_REGS being set.

The same logic will be reused for newly introduced
FTRACE_OPS_FL_PERMANENT flag, so make the function generic.

Signed-off-by: Miroslav Benes <mbenes@...e.cz>
---
 kernel/trace/ftrace.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 62a50bf399d6..a37c1127599c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1602,24 +1602,24 @@ int ftrace_text_reserved(const void *start, const void *end)
 	return (int)!!ret;
 }
 
-/* Test if ops registered to this rec needs regs */
-static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
+/* Test if ops registered to this rec needs to have a specified flag set */
+static bool test_rec_ops_needs_flag(struct dyn_ftrace *rec, int flag)
 {
 	struct ftrace_ops *ops;
-	bool keep_regs = false;
+	bool keep_flag = false;
 
 	for (ops = ftrace_ops_list;
 	     ops != &ftrace_list_end; ops = ops->next) {
 		/* pass rec in as regs to have non-NULL val */
 		if (ftrace_ops_test(ops, rec->ip, rec)) {
-			if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
-				keep_regs = true;
+			if (ops->flags & flag) {
+				keep_flag = true;
 				break;
 			}
 		}
 	}
 
-	return  keep_regs;
+	return keep_flag;
 }
 
 static struct ftrace_ops *
@@ -1750,7 +1750,8 @@ static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
 			if (ftrace_rec_count(rec) > 0 &&
 			    rec->flags & FTRACE_FL_REGS &&
 			    ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
-				if (!test_rec_ops_needs_regs(rec))
+				if (!test_rec_ops_needs_flag(rec,
+						FTRACE_OPS_FL_SAVE_REGS))
 					rec->flags &= ~FTRACE_FL_REGS;
 			}
 
-- 
2.23.0