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From: tip-bot for Namhyung Kim <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: rostedt@goodmis.org, tglx@linutronix.de, namhyung@kernel.org,
	linux-kernel@vger.kernel.org, hpa@linux.intel.com, hpa@zytor.com,
	mingo@kernel.org
Subject: [tip:x86/urgent] x86/ftrace: Add comment on static function tracing
Date: Thu, 19 Nov 2015 02:12:31 -0800	[thread overview]
Message-ID: <tip-112677d683d31ebd6a8e8b02e0620ae512354b2d@git.kernel.org> (raw)
In-Reply-To: <1447721004-2551-1-git-send-email-namhyung@kernel.org>

Commit-ID:  112677d683d31ebd6a8e8b02e0620ae512354b2d
Gitweb:     http://git.kernel.org/tip/112677d683d31ebd6a8e8b02e0620ae512354b2d
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Tue, 17 Nov 2015 09:43:24 +0900
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 19 Nov 2015 11:07:49 +0100

x86/ftrace: Add comment on static function tracing

There was a confusion between update_ftrace_function() and static
function tracing trampoline regarding 3rd parameter (ftrace_ops).
Add a comment for clarification.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1447721004-2551-1-git-send-email-namhyung@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/mcount_64.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 94ea120..87e1762 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -278,6 +278,12 @@ trace:
 	/* save_mcount_regs fills in first two parameters */
 	save_mcount_regs
 
+	/*
+	 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+	 * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
+	 * ip and parent ip are used and the list function is called when
+	 * function tracing is enabled.
+	 */
 	call   *ftrace_trace_function
 
 	restore_mcount_regs

      parent reply	other threads:[~2015-11-19 10:12 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-17  0:43 [PATCH] ftrace/x86: Add comment on static function tracing Namhyung Kim
2015-11-17  2:03 ` Steven Rostedt
2015-11-19 10:12 ` tip-bot for Namhyung Kim [this message]

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