x86: remove more 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_from_user_inatomic()" is mostly the special cases for the constant size, and it's actually almost never relevant. Most users aren't actually using a constant size anyway, and the few cases that do small constant copies are better off just using __get_user() instead. So get rid of the unnecessary complexity.

Linus Torvalds committed 10 years ago

Commit bd28b141 parent 5b09c3e4 files · +3 −31Browse files

Unified · Split

4 files

arch/x86/include/asm/uaccess_32.h +0 −26
kernel/events/uprobes.c +1 −2
kernel/futex.c +1 −1
mm/maccess.c +1 −2

arch/x86/include/asm/uaccess_32.h+0−26

@@ -65,32 +65,6 @@ __copy_to_user(void __user to, const void from, unsigned long n) · 64 unmodified lines
65	static __always_inline unsigned long	65	static __always_inline unsigned long
66	__copy_from_user_inatomic(void to, const void __user from, unsigned long n)	66	__copy_from_user_inatomic(void to, const void __user from, unsigned long n)
67	{	67	{
68	/* Avoid zeroing the tail if the copy fails..
69	* If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
70	* but as the zeroing behaviour is only significant when n is not
71	* constant, that shouldn't be a problem.
72	*/
73	if (__builtin_constant_p(n)) {
74	unsigned long ret;
75
76	switch (n) {
77	case 1:
78	__uaccess_begin();
79	__get_user_size((u8 )to, from, 1, ret, 1);
80	__uaccess_end();
81	return ret;
82	case 2:
83	__uaccess_begin();
84	__get_user_size((u16 )to, from, 2, ret, 2);
85	__uaccess_end();
86	return ret;
87	case 4:
88	__uaccess_begin();
89	__get_user_size((u32 )to, from, 4, ret, 4);
90	__uaccess_end();
91	return ret;
92	}
93	}
94	return __copy_from_user_ll_nozero(to, from, n);	68	return __copy_from_user_ll_nozero(to, from, n);
95	}	69	}
96		70

kernel/events/uprobes.c+1−2

@@ -1694,8 +1694,7 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) · 1693 unmodified lines
1694	int result;	1694	int result;
1695		1695
1696	pagefault_disable();	1696	pagefault_disable();
1697	result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,	1697	result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
1698	sizeof(opcode));
1699	pagefault_enable();	1698	pagefault_enable();
1700		1699
1701	if (likely(result == 0))	1700	if (likely(result == 0))

kernel/futex.c+1−1

@@ -729,7 +729,7 @@ static int get_futex_value_locked(u32 dest, u32 __user from) · 728 unmodified lines
729	int ret;	729	int ret;
730		730
731	pagefault_disable();	731	pagefault_disable();
732	ret = __copy_from_user_inatomic(dest, from, sizeof(u32));	732	ret = __get_user(*dest, from);
733	pagefault_enable();	733	pagefault_enable();
734		734
735	return ret ? -EFAULT : 0;	735	return ret ? -EFAULT : 0;

mm/maccess.c+1−2

@@ -96,8 +96,7 @@ long strncpy_from_unsafe(char dst, const void unsafe_addr, long count) · 95 unmodified lines
96	pagefault_disable();	96	pagefault_disable();
97		97
98	do {	98	do {
99	ret = __copy_from_user_inatomic(dst++,	99	ret = __get_user(dst++, (const char __user __force )src++);
100	(const void __user __force *)src++, 1);
101	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);	100	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
102		101
103	dst[-1] = '\0';	102	dst[-1] = '\0';