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Diffstat (limited to 'arch/sparc/lib/usercopy.c')
-rw-r--r--arch/sparc/lib/usercopy.c50
1 files changed, 21 insertions, 29 deletions
diff --git a/arch/sparc/lib/usercopy.c b/arch/sparc/lib/usercopy.c
index 851cb75ce189..87f96453403a 100644
--- a/arch/sparc/lib/usercopy.c
+++ b/arch/sparc/lib/usercopy.c
@@ -11,35 +11,20 @@ EXPORT_SYMBOL(copy_from_user_overflow);
11 11
12#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) 12#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
13 13
14/* Return the high bit set in the first byte that is a zero */ 14static inline long find_zero(unsigned long mask)
15static inline unsigned long has_zero(unsigned long a)
16{
17 return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80);
18}
19
20static inline long find_zero(unsigned long c)
21{ 15{
16 long byte = 0;
22#ifdef CONFIG_64BIT 17#ifdef CONFIG_64BIT
23 if (!(c & 0xff00000000000000UL)) 18 if (mask >> 32)
24 return 0; 19 mask >>= 32;
25 if (!(c & 0x00ff000000000000UL)) 20 else
26 return 1; 21 byte = 4;
27 if (!(c & 0x0000ff0000000000UL))
28 return 2;
29 if (!(c & 0x000000ff00000000UL))
30 return 3;
31#define __OFF 4
32#else
33#define __OFF 0
34#endif 22#endif
35 if (!(c & 0xff000000)) 23 if (mask >> 16)
36 return __OFF + 0; 24 mask >>= 16;
37 if (!(c & 0x00ff0000)) 25 else
38 return __OFF + 1; 26 byte += 2;
39 if (!(c & 0x0000ff00)) 27 return (mask >> 8) ? byte : byte + 1;
40 return __OFF + 2;
41 return __OFF + 3;
42#undef __OFF
43} 28}
44 29
45/* 30/*
@@ -50,6 +35,8 @@ static inline long find_zero(unsigned long c)
50 */ 35 */
51static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max) 36static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
52{ 37{
38 const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1;
39 const unsigned long low_bits = REPEAT_BYTE(0x7f);
53 long res = 0; 40 long res = 0;
54 41
55 /* 42 /*
@@ -63,14 +50,19 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
63 goto byte_at_a_time; 50 goto byte_at_a_time;
64 51
65 while (max >= sizeof(unsigned long)) { 52 while (max >= sizeof(unsigned long)) {
66 unsigned long c; 53 unsigned long c, v, rhs;
67 54
68 /* Fall back to byte-at-a-time if we get a page fault */ 55 /* Fall back to byte-at-a-time if we get a page fault */
69 if (unlikely(__get_user(c,(unsigned long __user *)(src+res)))) 56 if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
70 break; 57 break;
58 rhs = c | low_bits;
59 v = (c + high_bits) & ~rhs;
71 *(unsigned long *)(dst+res) = c; 60 *(unsigned long *)(dst+res) = c;
72 if (has_zero(c)) 61 if (v) {
73 return res + find_zero(c); 62 v = (c & low_bits) + low_bits;;
63 v = ~(v | rhs);
64 return res + find_zero(v);
65 }
74 res += sizeof(unsigned long); 66 res += sizeof(unsigned long);
75 max -= sizeof(unsigned long); 67 max -= sizeof(unsigned long);
76 } 68 }