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

["H. Peter Anvin" <hpa@zytor.com>]

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.

	-hpa