linux-kernel - [PATCH] sh/kprobes: Fix illslot handler not to unregister but disarm kprobe

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Message-ID: <20130619114244.19843.90351.stgit@mhiramat-M0-7522>
Date:	Wed, 19 Jun 2013 20:42:44 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	yrl.pp-manager.tt@...achi.com
Subject: [PATCH] sh/kprobes: Fix illslot handler not to unregister but disarm
 kprobe

Fix illegal slot exception handler not to unregister the kprobe
but just to disarm it. Since the unregister_kprobe must sleep (by
synchronize_sched), it must not be called from any exception/
interrupt handlers. Disarming is safe because it just recovers
original instruction code.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Paul Mundt <lethal@...ux-sh.org>
Cc: Sasha Levin <sasha.levin@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
---
 arch/sh/kernel/kprobes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index 42b46e6..5ec8182 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -82,7 +82,7 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 
 /**
  * If an illegal slot instruction exception occurs for an address
- * containing a kprobe, remove the probe.
+ * containing a kprobe, disarm the probe.
  *
  * Returns 0 if the exception was handled successfully, 1 otherwise.
  */
@@ -93,7 +93,7 @@ int __kprobes kprobe_handle_illslot(unsigned long pc)
 	if (p != NULL) {
 		printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
 		       (unsigned int)pc + 2);
-		unregister_kprobe(p);
+		arch_disarm_kprobe(p);
 		return 0;
 	}
 


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