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SubjectRe: [PATCH v3 4/4] x86, mpx: extend siginfo structure to include bound violation information
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


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