1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2013 ARM Ltd. 4 */ 5 #ifndef __ASM_WORD_AT_A_TIME_H 6 #define __ASM_WORD_AT_A_TIME_H 7 8 #include <linux/uaccess.h> 9 10 #ifndef __AARCH64EB__ 11 12 #include <linux/kernel.h> 13 14 struct word_at_a_time { 15 const unsigned long one_bits, high_bits; 16 }; 17 18 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } 19 20 static inline unsigned long has_zero(unsigned long a, unsigned long *bits, 21 const struct word_at_a_time *c) 22 { 23 unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits; 24 *bits = mask; 25 return mask; 26 } 27 28 #define prep_zero_mask(a, bits, c) (bits) 29 30 static inline unsigned long create_zero_mask(unsigned long bits) 31 { 32 bits = (bits - 1) & ~bits; 33 return bits >> 7; 34 } 35 36 static inline unsigned long find_zero(unsigned long mask) 37 { 38 return fls64(mask) >> 3; 39 } 40 41 #define zero_bytemask(mask) (mask) 42 43 #else /* __AARCH64EB__ */ 44 #include <asm-generic/word-at-a-time.h> 45 #endif 46 47 /* 48 * Load an unaligned word from kernel space. 49 * 50 * In the (very unlikely) case of the word being a page-crosser 51 * and the next page not being mapped, take the exception and 52 * return zeroes in the non-existing part. 53 */ 54 static inline unsigned long load_unaligned_zeropad(const void *addr) 55 { 56 unsigned long ret; 57 58 __uaccess_enable_tco_async(); 59 60 /* Load word from unaligned pointer addr */ 61 asm( 62 "1: ldr %0, %2\n" 63 "2:\n" 64 _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1) 65 : "=&r" (ret) 66 : "r" (addr), "Q" (*(unsigned long *)addr)); 67 68 __uaccess_disable_tco_async(); 69 70 return ret; 71 } 72 73 #endif /* __ASM_WORD_AT_A_TIME_H */ 74