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Commit 30e3024b authored by Linus Torvalds's avatar Linus Torvalds Committed by Alex Shi
Browse files

x86: remove pointless uaccess_32.h complexity 



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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 5b09c3edecd37ec1a52fbd5ae97a19734edc7a77)
Signed-off-by: default avatarAlex Shi <alex.shi@linaro.org>
parent 9a6d5a02

arch/x86/include/asm/uaccess_32.h

+0 −36
Original line number Diff line number Diff line
@@ -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);

}

drivers/gpu/drm/i915/i915_gem_execbuffer.c

+1 −3
Original line number Diff line number Diff line
@@ -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;

			}