1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2012 Regents of the University of California 4 * 5 * Derived from arch/x86/include/asm/word-at-a-time.h 6 */ 7 8 #ifndef _ASM_RISCV_WORD_AT_A_TIME_H 9 #define _ASM_RISCV_WORD_AT_A_TIME_H 10 11 12 #include <asm/asm-extable.h> 13 #include <linux/bitops.h> 14 #include <linux/wordpart.h> 15 16 struct word_at_a_time { 17 const unsigned long one_bits, high_bits; 18 }; 19 20 #define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) } 21 22 static inline unsigned long has_zero(unsigned long val, 23 unsigned long *bits, const struct word_at_a_time *c) 24 { 25 unsigned long mask = ((val - c->one_bits) & ~val) & c->high_bits; 26 *bits = mask; 27 return mask; 28 } 29 30 static inline unsigned long prep_zero_mask(unsigned long val, 31 unsigned long bits, const struct word_at_a_time *c) 32 { 33 return bits; 34 } 35 36 static inline unsigned long create_zero_mask(unsigned long bits) 37 { 38 bits = (bits - 1) & ~bits; 39 return bits >> 7; 40 } 41 42 static inline unsigned long find_zero(unsigned long mask) 43 { 44 return fls64(mask) >> 3; 45 } 46 47 /* The mask we created is directly usable as a bytemask */ 48 #define zero_bytemask(mask) (mask) 49 50 #ifdef CONFIG_DCACHE_WORD_ACCESS 51 52 /* 53 * Load an unaligned word from kernel space. 54 * 55 * In the (very unlikely) case of the word being a page-crosser 56 * and the next page not being mapped, take the exception and 57 * return zeroes in the non-existing part. 58 */ 59 static inline unsigned long load_unaligned_zeropad(const void *addr) 60 { 61 unsigned long ret; 62 63 /* Load word from unaligned pointer addr */ 64 asm( 65 "1: " REG_L " %0, %2\n" 66 "2:\n" 67 _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1) 68 : "=&r" (ret) 69 : "r" (addr), "m" (*(unsigned long *)addr)); 70 71 return ret; 72 } 73 74 #endif /* CONFIG_DCACHE_WORD_ACCESS */ 75 76 #endif /* _ASM_RISCV_WORD_AT_A_TIME_H */ 77