linux-kernel - [for-next][PATCH 6/7] ftrace: Add another check for match in register_ftrace

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Date:   Sun, 17 Nov 2019 17:13:02 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [for-next][PATCH 6/7] ftrace: Add another check for match in register_ftrace_direct()

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

As an instruction pointer passed into register_ftrace_direct() may just
exist on the ftrace call site, but may not be the start of the call site
itself, register_ftrace_direct() still needs to update test if a direct call
exists on the normalized site, as only one direct call is allowed at any one
time.

Fixes: 763e34e74bb7d ("ftrace: Add register_ftrace_direct()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 kernel/trace/ftrace.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 32e4e5ffdd97..9fe33ebaf914 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5030,7 +5030,12 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
 		goto out_unlock;
 
 	/* Make sure the ip points to the exact record */
-	ip = rec->ip;
+	if (ip != rec->ip) {
+		ip = rec->ip;
+		/* Need to check this ip for a direct. */
+		if (find_rec_direct(ip))
+			goto out_unlock;
+	}
 
 	ret = -ENOMEM;
 	if (ftrace_hash_empty(direct_functions) ||
-- 
2.24.0