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From: Wang Nan <wangnan0@huawei.com>
To: <masami.hiramatsu.pt@hitachi.com>, <tixy@linaro.org>,
	<linux@arm.linux.org.uk>
Cc: <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>
Subject: [PATCH] kprobes: bugfix: set kprobes_all_disarmed earlier to enable re-optimization.
Date: Mon, 5 Jan 2015 20:31:15 +0800	[thread overview]
Message-ID: <1420461075-27012-1-git-send-email-wangnan0@huawei.com> (raw)

In original code, the probed instruction doesn't get optimized after

echo 0 > /sys/kernel/debug/kprobes/enabled
echo 1 > /sys/kernel/debug/kprobes/enabled

This is because original code checks kprobes_all_disarmed in
optimize_kprobe(), but this flag is turned off after calling that
function. Therefore, optimize_kprobe() will see
kprobes_all_disarmed == true and doesn't do the optimization.

This patch simply turns off kprobes_all_disarmed earlier to enable
optimization.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 kernel/kprobes.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index bad4e95..b185464 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2320,6 +2320,12 @@ static void arm_all_kprobes(void)
 	if (!kprobes_all_disarmed)
 		goto already_enabled;
 
+	/*
+	 * optimize_kprobe() called by arm_kprobe() checks
+	 * kprobes_all_disarmed, so set kprobes_all_disarmed before
+	 * arm_kprobe.
+	 */
+	kprobes_all_disarmed = false;
 	/* Arming kprobes doesn't optimize kprobe itself */
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
@@ -2328,7 +2334,6 @@ static void arm_all_kprobes(void)
 				arm_kprobe(p);
 	}
 
-	kprobes_all_disarmed = false;
 	printk(KERN_INFO "Kprobes globally enabled\n");
 
 already_enabled:
-- 
1.8.4


             reply	other threads:[~2015-01-05 12:36 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-05 12:31 Wang Nan [this message]
2015-01-12 11:24 ` Masami Hiramatsu
2015-01-20  3:02   ` Wang Nan
2015-01-20  7:12     ` Masami Hiramatsu
2015-02-19  0:10       ` Ingo Molnar

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