Date: Fri, 29 Apr 2005 19:27:59 +0200
From: Juergen Quade <quade@hs-niederrhein.de>
To: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: system-freeze: kprobe and do_gettimeofday
Message-ID: <20050429172759.GA27647@hsnr.de>
References: <20050423101251.GA327@hsnr.de> <20050425155649.GA30272@in.ibm.com> <20050425160859.GA23019@hsnr.de> <20050426145210.GC32766@in.ibm.com> <20050426193440.GA16597@hsnr.de> <20050429111849.GA5185@in.ibm.com>
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> > ...
> Thanks for providing the information, we are not able to reproduce this
> problem here. Can you pls write a similar fault handler for kprobes as shown
> below and get us the log messages.
> 
> int fault_probe(struct kprobe *p, struct pt_regs *regs, int trapnr) {
>         printk("fault_handler:p->addr=0x%p, eflags=0x%lx\n", p->addr, regs->eflags);
>         return 0;

I tried it a few time, system freezes but the fault handler
has not been called. First time the system rebooted completly,
second time I got no output at all.

I added the proposed line into the pre-handler. Here is the
output:

	kprobe registered address c0107bd0
	pre_handler:p->addr=0xc0107bd0, eflags=0x282
	root@esz-mobil:/tmp/kprobes# double fault, gdt
	at c049bd00 ...

The first line is the output of "init_module". The second
line is the output of the pre_handler. As you can see,
before the "double fault" message I get one prompt. Could
there be a problem with the timer interrupt?

         Juergen.
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