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x86: remove pointless uaccess_32.h complexity

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I'm looking at trying to possibly merge the 32-bit and 64-bit versions
of the x86 uaccess.h implementation, but first this needs to be cleaned
up.

For example, the 32-bit version of "__copy_to_user_inatomic()" is mostly
the special cases for the constant size, and it's actually never
relevant.  Every user except for one aren't actually using a constant
size anyway, and the one user that uses it is better off just using
__put_user() instead.

So get rid of the unnecessary complexity.

[ The same cleanup should likely happen to __copy_from_user_inatomic()
  as well, but that one has a lot more users that I need to take a look
  at first ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 5b09c3edec)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
This commit is contained in:
Linus Torvalds 2016-05-22 14:19:37 -07:00 • committed by Alex Shi
commit 30e3024be4
2 changed files with 1 additions and 39 deletions
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36
arch/x86/include/asm/uaccess_32.h
View file

@ -33,46 +33,10 @@ unsigned long __must_check __copy_from_user_ll_nocache_nozero
* the specified block with access_ok() before calling this function.
* The caller should also make sure he pins the user space address
* so that we don't result in page fault and sleep.
*
* Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
* we return the initial request size (1, 2 or 4), as copy_*_user should do.
* If a store crosses a page boundary and gets a fault, the x86 will not write
* anything, so this is accurate.
*/
static __always_inline unsigned long __must_check
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
{
if (__builtin_constant_p(n)) {
unsigned long ret;
switch (n) {
case 1:
__uaccess_begin();
__put_user_size(*(u8 *)from, (u8 __user *)to,
1, ret, 1);
__uaccess_end();
return ret;
case 2:
__uaccess_begin();
__put_user_size(*(u16 *)from, (u16 __user *)to,
2, ret, 2);
__uaccess_end();
return ret;
case 4:
__uaccess_begin();
__put_user_size(*(u32 *)from, (u32 __user *)to,
4, ret, 4);
__uaccess_end();
return ret;
case 8:
__uaccess_begin();
__put_user_size(*(u64 *)from, (u64 __user *)to,
8, ret, 8);
__uaccess_end();
return ret;
}
}
return __copy_to_user_ll(to, from, n);
}

4
drivers/gpu/drm/i915/i915_gem_execbuffer.c
View file

@ -513,9 +513,7 @@ i915_gem_execbuffer_relocate_vma(struct i915_vma *vma,
return ret;
if (r->presumed_offset != offset &&
__copy_to_user_inatomic(&user_relocs->presumed_offset,
&r->presumed_offset,
sizeof(r->presumed_offset))) {
__put_user(r->presumed_offset, &user_relocs->presumed_offset)) {
return -EFAULT;
}