1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_WORD_AT_A_TIME_H 3 #define _ASM_WORD_AT_A_TIME_H 4 5 #include <linux/bitops.h> 6 #include <linux/wordpart.h> 7 8 struct word_at_a_time { 9 const unsigned long one_bits, high_bits; 10 }; 11 12 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } 13 14 /* Return nonzero if it has a zero */ 15 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c) 16 { 17 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; 18 *bits = mask; 19 return mask; 20 } 21 22 static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c) 23 { 24 return bits; 25 } 26 27 #ifdef CONFIG_64BIT 28 29 /* Keep the initial has_zero() value for both bitmask and size calc */ 30 #define create_zero_mask(bits) (bits) 31 32 static inline unsigned long zero_bytemask(unsigned long bits) 33 { 34 bits = (bits - 1) & ~bits; 35 return bits >> 7; 36 } 37 38 #define find_zero(bits) (__ffs(bits) >> 3) 39 40 #else 41 42 /* Create the final mask for both bytemask and size */ 43 static inline unsigned long create_zero_mask(unsigned long bits) 44 { 45 bits = (bits - 1) & ~bits; 46 return bits >> 7; 47 } 48 49 /* The mask we created is directly usable as a bytemask */ 50 #define zero_bytemask(mask) (mask) 51 52 /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ 53 static inline unsigned long find_zero(unsigned long mask) 54 { 55 /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ 56 long a = (0x0ff0001+mask) >> 23; 57 /* Fix the 1 for 00 case */ 58 return a & mask; 59 } 60 61 #endif 62 63 /* 64 * Load an unaligned word from kernel space. 65 * 66 * In the (very unlikely) case of the word being a page-crosser 67 * and the next page not being mapped, take the exception and 68 * return zeroes in the non-existing part. 69 */ 70 static inline unsigned long load_unaligned_zeropad(const void *addr) 71 { 72 unsigned long ret; 73 74 asm volatile( 75 "1: mov %[mem], %[ret]\n" 76 "2:\n" 77 _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_ZEROPAD) 78 : [ret] "=r" (ret) 79 : [mem] "m" (*(unsigned long *)addr)); 80 81 return ret; 82 } 83 84 #endif /* _ASM_WORD_AT_A_TIME_H */ 85