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/kernel.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 val, 22 unsigned long *bits, const struct word_at_a_time *c) 23 { 24 unsigned long mask = ((val - c->one_bits) & ~val) & c->high_bits; 25 *bits = mask; 26 return mask; 27 } 28 29 static inline unsigned long prep_zero_mask(unsigned long val, 30 unsigned long bits, const struct word_at_a_time *c) 31 { 32 return bits; 33 } 34 35 static inline unsigned long create_zero_mask(unsigned long bits) 36 { 37 bits = (bits - 1) & ~bits; 38 return bits >> 7; 39 } 40 41 static inline unsigned long find_zero(unsigned long mask) 42 { 43 return fls64(mask) >> 3; 44 } 45 46 /* The mask we created is directly usable as a bytemask */ 47 #define zero_bytemask(mask) (mask) 48 49 #ifdef CONFIG_DCACHE_WORD_ACCESS 50 51 /* 52 * Load an unaligned word from kernel space. 53 * 54 * In the (very unlikely) case of the word being a page-crosser 55 * and the next page not being mapped, take the exception and 56 * return zeroes in the non-existing part. 57 */ 58 static inline unsigned long load_unaligned_zeropad(const void *addr) 59 { 60 unsigned long ret; 61 62 /* Load word from unaligned pointer addr */ 63 asm( 64 "1: " REG_L " %0, %2\n" 65 "2:\n" 66 _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1) 67 : "=&r" (ret) 68 : "r" (addr), "m" (*(unsigned long *)addr)); 69 70 return ret; 71 } 72 73 #endif /* CONFIG_DCACHE_WORD_ACCESS */ 74 75 #endif /* _ASM_RISCV_WORD_AT_A_TIME_H */ 76