linux-kernel - [PATCH -tip v2 2/2] x86: Issue at least one memory barrier in stop_machine_text

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100304033850.3819.74590.stgit@localhost6.localdomain6>
Date:	Wed, 03 Mar 2010 22:38:50 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, lkml <linux-kernel@...r.kernel.org>
Cc:	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Ingo Molnar <mingo@...e.hu>, Jason Baron <jbaron@...hat.com>
Subject: [PATCH -tip v2 2/2] x86: Issue at least one memory barrier in
	stop_machine_text_poke().

Fix stop_machine_text_poke() to issue smp_mb() before exiting waiting
loop, and use cpu_relax() for waiting.

Changes in v2:
 - Don't use ACCESS_ONCE().

Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Jason Baron <jbaron@...hat.com>
---

 arch/x86/kernel/alternative.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 635e4f4..3a4bf35 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -597,8 +597,8 @@ static int __kprobes stop_machine_text_poke(void *data)
 		wrote_text = 1;
 	} else {
 		while (!wrote_text)
-			smp_rmb();
-		sync_core();
+			cpu_relax();
+		smp_mb();	/* Load wrote_text before following execution */
 	}
 
 	flush_icache_range((unsigned long)tpp->addr,


-- 
Masami Hiramatsu
e-mail: mhiramat@...hat.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/