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	65	static __always_inline unsigned long
66	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	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	1694	int result;
1695	1695
1696	1696	pagefault_disable();
1697		− result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
1698		− sizeof(opcode));
	1697	+ result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr);
1699	1698	pagefault_enable();
1700	1699
1701	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	729	int ret;
730	730
731	731	pagefault_disable();
732		− ret = __copy_from_user_inatomic(dest, from, sizeof(u32));
	732	+ ret = __get_user(*dest, from);
733	733	pagefault_enable();
734	734
735	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	96	pagefault_disable();
97	97
98	98	do {
99		− ret = __copy_from_user_inatomic(dst++,
100		− (const void __user __force *)src++, 1);
	99	+ ret = __get_user(dst++, (const char __user __force )src++);
101	100	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
102	101
103	102	dst[-1] = '\0';