arch/riscv/include/asm/word-at-a-time.h

   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 */