From 5b09c3edecd37ec1a52fbd5ae97a19734edc7a77 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun, 22 May 2016 14:19:37 -0700
Subject: [PATCH] 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>
---
arch/x86/include/asm/uaccess_32.h | 36 ----------------------
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 4 +--
2 files changed, 1 insertion(+), 39 deletions(-)
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 3fe0eac59462b..537cc883ea29b 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 a676eedb441bf..d4d7c88ab5954 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;
}
--
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