linux-kernel - Re: perf_fuzzer compiled for x32 causes reboot

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Date:	Mon, 24 Feb 2014 09:42:42 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vince Weaver <vincent.weaver@...ne.edu>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H.J. Lu" <hjl.tools@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: perf_fuzzer compiled for x32 causes reboot

On 02/24/2014 09:41 AM, Vince Weaver wrote:
> On Mon, 24 Feb 2014, Vince Weaver wrote:
> 
>> I do note that 
>> 	perf_callchain_user();
>>
>> Does
>> 	fp = (void __user *)regs->bp;
>> 	
>> 	...
>>
>> 	bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
>>
>>
>> And in my particular executable RBP has nothing to do with a frame 
>> pointer, but is instead being used as a general purpose register.
> 
> and as a reminder, I'm seeing this on an x32 executable, so 
> perf_callchain_user32() is probably coming into play.
> 
> So maybe it is an x32 issue after all.
> 

No.

	if (!test_thread_flag(TIF_IA32))
		return 0;

TIF_IA32 is clear for an x32 process.

	-hpa

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