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: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 1 insertions, 39 deletions

diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 3fe0eac59462..537cc883ea29 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -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);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a676eedb441b..d4d7c88ab595 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -535,9 +535,7 @@ 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;
                         }