From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Subject: Re: [RFCv1 12/12] ARM: add get_user() support for 8 byte types
Date: Sun, 6 Oct 2013 09:53:54 +0100
Message-ID: <20131006085354.GC12758@n2100.arm.linux.org.uk>
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To: Rob Clark <robdclark@gmail.com>
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On Sat, Oct 05, 2013 at 08:45:50PM -0400, Rob Clark wrote:
> A new atomic modeset/pageflip ioctl being developed in DRM requires
> get_user() to work for 64bit types (in addition to just put_user()).
> 
> v1: original
> v2: pass correct size to check_uaccess, and better handling of narrowing
>     double word read with __get_user_xb() (Russell King's suggestion)

I thought we had decided not to support this for 32-bit because x86_32
had problems here as well:

#ifdef CONFIG_X86_32
#define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
#define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
#else
#define __get_user_asm_u64(x, ptr, retval, errret) \
         __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
#define __get_user_asm_ex_u64(x, ptr) \
         __get_user_asm_ex(x, ptr, "q", "", "=r")
#endif