x86, mm: Use a bitfield to mask nuisance get_user() warnings
x86, mm: Use a bitfield to mask nuisance get_user() warnings

Even though it is never executed, gcc wants to warn for casting from
a large integer to a pointer.  Furthermore, using a variable with
__typeof__() doesn't work because __typeof__ retains storage
specifiers (const, restrict, volatile).

However, we can declare a bitfield using sizeof(), which is legal
because sizeof() is a constant expression.  This quiets the warning,
although the code generated isn't 100% identical from the baseline
before 96477b4 x86-32: Add support for 64bit get_user():

[x86-mb is baseline, x86-mm is this commit]

   text      data        bss     filename
113716147  15858380   35037184   tip.x86-mb/o.i386-allconfig/vmlinux
113716145  15858380   35037184   tip.x86-mm/o.i386-allconfig/vmlinux
 12989837   3597944   12255232   tip.x86-mb/o.i386-modconfig/vmlinux
 12989831   3597944   12255232   tip.x86-mm/o.i386-modconfig/vmlinux
  1462784    237608    1401988   tip.x86-mb/o.i386-noconfig/vmlinux
  1462837    237608    1401964   tip.x86-mm/o.i386-noconfig/vmlinux
  7938994    553688    7639040   tip.x86-mb/o.i386-pae/vmlinux
  7943136    557784    7639040   tip.x86-mm/o.i386-pae/vmlinux
  7186126    510572    6574080   tip.x86-mb/o.i386/vmlinux
  7186124    510572    6574080   tip.x86-mm/o.i386/vmlinux
103747269  33578856   65888256   tip.x86-mb/o.x86_64-allconfig/vmlinux
103746949  33578856   65888256   tip.x86-mm/o.x86_64-allconfig/vmlinux
 12116695  11035832   20160512   tip.x86-mb/o.x86_64-modconfig/vmlinux
 12116567  11035832   20160512   tip.x86-mm/o.x86_64-modconfig/vmlinux
  1700790    380524     511808   tip.x86-mb/o.x86_64-noconfig/vmlinux
  1700790    380524     511808   tip.x86-mm/o.x86_64-noconfig/vmlinux
 12413612   1133376    1101824   tip.x86-mb/o.x86_64/vmlinux
 12413484   1133376    1101824   tip.x86-mm/o.x86_64/vmlinux

Cc: Jamie Lokier <b4dde37aa2aac745c0e6c43447507eaeace3e59f@shareable.org>
Cc: Ville Syrjälä <cd6e8d405ca90be3a03d5427c5b24fbd2d68dcc4@linux.intel.com>
Cc: Borislav Petkov <0691a664b24b6f15b20cd5aee64b72271db08be1@alien8.de>
Cc: Russell King <ba324ca7b1c77fc20bb970d5aff6eea9377918a5@arm.linux.org.uk>
Cc: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Link: f32f3248b46eb82c83cd1d4162788159ee406765@n2100.arm.linux.org.uk
Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs