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Message-ID: <52E5BCD5.8090408@intel.com>
Date: Mon, 27 Jan 2014 09:56:37 +0800
From: Ren Qiaowei <qiaowei.ren@intel.com>
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To: "H. Peter Anvin" <hpa@zytor.com>, David Rientjes <rientjes@google.com>
CC: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 4/4] x86, mpx: extend siginfo structure to include
 bound violation information
References: <1390727338-20487-1-git-send-email-qiaowei.ren@intel.com> <1390727338-20487-5-git-send-email-qiaowei.ren@intel.com> <alpine.DEB.2.02.1401252010400.10325@chino.kir.corp.google.com> <52E4919B.8050408@intel.com> <alpine.DEB.2.02.1401261335400.26515@chino.kir.corp.google.com> <52E5B7AA.9060205@intel.com> <52E5BC03.3080207@zytor.com>
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On 01/27/2014 09:53 AM, H. Peter Anvin wrote:
> On 01/26/2014 05:34 PM, Ren Qiaowei wrote:
>>>
>> I agree with you and we should suppress all the warnings as possible. If
>> I use (unsgined long) to cast like the following code, what do you think
>> about it? sizeof(long) will be 4 for 32-bit.
>>
>>      info->si_lower = (void __user *)(unsigned long)
>>          (xsave_buf->bndregs.bndregs[2*bndregno]);
>>      info->si_upper = (void __user *)(unsigned long)
>>      (~xsave_buf->bndregs.bndregs[2*bndregno+1]);
>>
>
> That is the way it is usually done, yes.  Add a comment saying something
> like:
>
> 	/* Note: the upper 32 bits are ignored in 32-bit mode. */
>
> It is worth watching out a bit here, though, because you could be
> running a 32-bit process on top of a 64-bit kernel.
>
Ok. I will update it in next version.

Thanks,
Qiaowei