Message-ID: <441FCCF8.1060300@intel.com>
Date: Tue, 21 Mar 2006 17:52:56 +0800
From: "bibo,mao" <bibo.mao@intel.com>
User-Agent: Thunderbird 1.5 (X11/20051201)
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To: Andrew Morton <akpm@osdl.org>
CC: linux-kernel@vger.kernel.org,
       Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
       "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>,
       Prasanna S Panchamukhi <prasanna@in.ibm.com>,
       Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Subject: [PATCH] kretprobe spinlock recursive remove
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In recent linux kernel version, kretprobe in IA32 is implemented in 
kretprobe_trampoline. And break trap code is removed from 
retprobe_trampoline, instead trampoline_handler is called directly. 
Currently if kretprobe hander hit one trap which causes another 
kretprobe, there will be SPINLOCK recursive bug. This patch fixes this, 
and will skip trap during kretprobe handler execution. This patch is 
based on 2.6.16-rc6-mm2.

--- arch/i386/kernel/kprobes.c.bak	2006-03-21 10:35:34.000000000 +0800
+++ arch/i386/kernel/kprobes.c	2006-03-21 10:37:44.000000000 +0800
@@ -390,8 +390,11 @@ fastcall void *__kprobes trampoline_hand
  			/* another task is sharing our hash bucket */
                          continue;

-		if (ri->rp && ri->rp->handler)
+		if (ri->rp && ri->rp->handler){
+			__get_cpu_var(current_kprobe) = &ri->rp->kp;
  			ri->rp->handler(ri, regs);
+			__get_cpu_var(current_kprobe) = NULL;
+		}

  		orig_ret_address = (unsigned long)ri->ret_addr;
  		recycle_rp_inst(ri);
-
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