LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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>, <lizefan@huawei.com>
Subject: [PATCH] kprobes: bugfix: force unoptimize when disable kprobes.
Date: Mon, 5 Jan 2015 20:32:20 +0800	[thread overview]
Message-ID: <1420461140-27153-1-git-send-email-wangnan0@huawei.com> (raw)

Original code failed to disarm the probed instruction after

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

if OPTPROBE is enabled.

This is caused by a piece of logically inconsistent code:

	unoptimize_kprobe(p, false);
	if (!kprobe_queued(p)) {
		...
	}

unoptimize_kprobe() with 'force' == false queues p onto
unoptimizing_list, so following kprobe_queued() check always fail unless
another core schedules optimizer and does the unoptimization very soon.
This logic causes arch_disarm_kprobe() failed to get execute, lefts a
breakpoint at the probed address, instead of restoring it.

This patch uses force unoptimize instead.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 kernel/kprobes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index b185464..9fbe0c3 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -869,7 +869,7 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt)
 {
 	struct kprobe *_p;
 
-	unoptimize_kprobe(p, false);	/* Try to unoptimize */
+	unoptimize_kprobe(p, true);	/* Try to unoptimize */
 
 	if (!kprobe_queued(p)) {
 		arch_disarm_kprobe(p);
-- 
1.8.4


             reply	other threads:[~2015-01-05 12:38 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-05 12:32 Wang Nan [this message]
2015-01-12 11:42 ` Masami Hiramatsu
2015-01-12 12:09   ` [PATCH] kprobes: bugfix: checks kprobes_all_disarmed in unoptimized_kprobe() Wang Nan
2015-01-12 12:52     ` Masami Hiramatsu
2015-01-19  3:04       ` Wang Nan
2015-01-19  9:05         ` Masami Hiramatsu
2015-01-19 11:21           ` Wang Nan
2015-01-19 12:45             ` Masami Hiramatsu
2015-01-19 12:59               ` Wang Nan
2015-01-20  2:51               ` [PATCH] kprobes: bugfix: makes kprobes/enabled works correctly for optimized kprobes Wang Nan
2015-01-20  7:12                 ` Masami Hiramatsu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1420461140-27153-1-git-send-email-wangnan0@huawei.com \
    --to=wangnan0@huawei.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@arm.linux.org.uk \
    --cc=lizefan@huawei.com \
    --cc=masami.hiramatsu.pt@hitachi.com \
    --cc=tixy@linaro.org \
    --subject='Re: [PATCH] kprobes: bugfix: force unoptimize when disable kprobes.' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).