linux-kernel - Re: [PATCH 0/5 v2] [GIT PULL] x86/jump label: Paranoid checks and 2 or 5 byte nops

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Message-ID: <20120131194813.GA12074@elte.hu>
Date:	Tue, 31 Jan 2012 20:48:13 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jason Baron <jbaron@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 0/5 v2] [GIT PULL] x86/jump label: Paranoid checks and 2
 or 5 byte nops


* Steven Rostedt <rostedt@...dmis.org> wrote:

> On Mon, 2012-01-30 at 15:48 +0100, Ingo Molnar wrote:
> > * Steven Rostedt <rostedt@...dmis.org> wrote:
> > 
> > > 
> > > Ingo,
> > > 
> > > This is the second round with the suggestions made by Peter 
> > > and Andrew incorporated (and tested).
> > 
> > they are crashing my testbox:
> > 
> > Policy zone: DMA32
> > Kernel command line: root=/dev/sda6 earlyprintk=ttyS0,115200 
> > console=ttyS0,115200 debug initcall_de
> > bug sysrq_always_enabled ignore_loglevel selinux=0 
> > nmi_watchdog=1 panic=1 3
> > sysrq: sysrq always enabled.
> > PANIC: early exception 06 rip 10:ffffffff8101546d error 0 cr2 
> > f06f53
> > Pid: 0, comm: swapper Not tainted 
> > 3.3.0-rc1-tip-02083-ga5066f8-dirty #170372
> > Call Trace:
> >  [<ffffffff8101546d>] ? __jump_label_transform+0x81/0x14e
> >  [<ffffffff81063ee4>] ? try_to_wake_up+0x1f8/0x2cc
> >  [<ffffffff8184d19e>] early_idt_handler+0x5e/0x71
> >  [<ffffffff8101546d>] ? __jump_label_transform+0x81/0x14e
> >  [<ffffffff81015457>] ? __jump_label_transform+0x6b/0x14e
> >  [<ffffffff810155f8>] arch_jump_label_transform_static+0x6f/0x77
> >  [<ffffffff81865162>] jump_label_init+0x68/0x98
> >  [<ffffffff8184d98b>] start_kernel+0x182/0x3b8
> >  [<ffffffff8184d2c3>] x86_64_start_reservations+0xae/0xb2
> >  [<ffffffff8184d40d>] x86_64_start_kernel+0x146/0x153
> > RIP __jump_label_transform+0x81/0x14e
> > 
> > Do you need the config or is the bug obvious at first sight?
> 
> Could you post the exact line of that address?
> 
> <ffffffff8101546d>
>
> I know there was some work to default enable some code. I'm 
> not sure how much made it in. I'm thinking the line you 
> triggered was:
> 		/*
> 		 * The location is not a nop that we were expecting,
> 		 * something went wrong. Crash the box, as something could be
> 		 * corrupting the kernel.
> 		 */
> 		BUG();

Correct, it's the ud2.

> It hits this if we enable a nop that is not what we expect it to be.
> 
> Yeah, send me the config too, and I'll run this against tip/master with
> all the patches applied.

Attached. (you need to run it through make oldconfig and use the 
defaults.)

Thanks,

	Ingo

View attachment "config" of type "text/plain" (74056 bytes)