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