diff options
| -rw-r--r-- | arch/sparc/lib/usercopy.c | 50 |
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); #define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) -/* Return the high bit set in the first byte that is a zero */ -static inline unsigned long has_zero(unsigned long a) -{ - return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80); -} - -static inline long find_zero(unsigned long c) +static inline long find_zero(unsigned long mask) { + long byte = 0; #ifdef CONFIG_64BIT - if (!(c & 0xff00000000000000UL)) - return 0; - if (!(c & 0x00ff000000000000UL)) - return 1; - if (!(c & 0x0000ff0000000000UL)) - return 2; - if (!(c & 0x000000ff00000000UL)) - return 3; -#define __OFF 4 -#else -#define __OFF 0 + if (mask >> 32) + mask >>= 32; + else + byte = 4; #endif - if (!(c & 0xff000000)) - return __OFF + 0; - if (!(c & 0x00ff0000)) - return __OFF + 1; - if (!(c & 0x0000ff00)) - return __OFF + 2; - return __OFF + 3; -#undef __OFF + if (mask >> 16) + mask >>= 16; + else + byte += 2; + return (mask >> 8) ? byte : byte + 1; } /* @@ -50,6 +35,8 @@ static inline long find_zero(unsigned long c) */ static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max) { + const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1; + const unsigned long low_bits = REPEAT_BYTE(0x7f); long res = 0; /* @@ -63,14 +50,19 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long goto byte_at_a_time; while (max >= sizeof(unsigned long)) { - unsigned long c; + unsigned long c, v, rhs; /* Fall back to byte-at-a-time if we get a page fault */ if (unlikely(__get_user(c,(unsigned long __user *)(src+res)))) break; + rhs = c | low_bits; + v = (c + high_bits) & ~rhs; *(unsigned long *)(dst+res) = c; - if (has_zero(c)) - return res + find_zero(c); + if (v) { + v = (c & low_bits) + low_bits;; + v = ~(v | rhs); + return res + find_zero(v); + } res += sizeof(unsigned long); max -= sizeof(unsigned long); } |